Scientifically Minded

Author's Note: All characters over eighteen.

****

I walked into my bedroom and found my sister sprawled out on my bed. Nova was lying on her stomach, legs idly kicking back and forth in the air, her phone and notebook in front of her.

"Hey bro," she greeted me.

"Hey yourself," I said, shrugging out of my hoodie.

Nova had gotten into the bad habit of wearing some very, very tight shorts lately. The way she lay in my bed showed off her cute butt way too nicely, though she kindly didn't turn to look at me and gave me the chance to stare a moment before sitting on the bed next to her.

"You know you have a room of your own, yeah?" I said.

Nova shrugged. "What fun's that?"

"I mean..."

"Besides, I wanted to ask you some things."

I rolled my eyes. "Of course you do. You've been asking such weird questions lately."

"Have not," Nova pouted, acting offended. "I'm doing research. Learning. Bettering myself. These are noble endeavours."

"Last week you asked me whether you should start wearing a padded bra," I said.

"To make my tits look bigger," Nova said, as though it was perfectly reasonable.

"The week before, about what kind of shorts to wear to make your butt look good," I continued.

Nova wiggled her booty. "How are these ones doing?"

"I mean... fantastic, and I think you know that," I said.

She grinned, fully pleased with herself. "Good. I thought so."

"Why are you asking me these things though?" I asked. "It's weird."

"It's not," Nova said. "You're a boy, Sol."

"Thanks for noticing."

"And you've got relevant opinions," she said. "Plus I know when you stare at my ass, you really mean it."

"... is there a way to stare at an ass and not mean it?" I asked.

"Well, you know," she said airily. "It means more coming from you."

"You shouldn't want your brother staring at your ass," I said. "Or helping you pick out bras to make your tits look bigger."

Nova chewed the end of her pen, somehow making it look cute and naughty while she pondered. "Do you like staring at my ass?" she finally asked.

"In those shorts? Yeah."

"So we're both winning then."

"One could so argue," I agreed evasively.

Nova took the time to jot down a note in her book. Something about me, no doubt. She was doing that a lot lately. It probably made me look like a perv, all full of remarks about how I liked her butt and which bras looked best on her. Not my fault. She asked.

"You don't show this stuff to anyone, do you?" I asked. "Whatever you're writing in there?"

"It's research for making myself attractive," Nova said. "I've told you that. I don't show anyone, but I do talk about it with my friends."

"Oh god."

"What? It's useful. They benefit too. You want me to hoard knowledge?"

"How much new and fresh knowledge are you really gaining here?" I asked.

"Plenty," Nova assured me. "Like the right amount of midriff to show off to get you to peek without making Mom and Dad mad. That's useful. And that these shorts work. I was worried too tight was going to be slutty or not really look good actually. But it seems to be working out."

I blushed as I realized she'd caught me staring again. I hadn't even meant to. It just happened, the way her butt cheeks were perfectly shown off in near-skintight shorts, and the way her kicking legs kept drawing my eye. That was probably part of her experimentation too, though she hadn't mentioned it specifically.

"The shorts might be pushing it if you're trying not to get a talking to about your outfits," I said, attempting to deflect from my indiscretion.

"I think so too," Nova said, wrinkling her brow in thought. "But I've been trying out cunningly not letting the wrong people see them from behind. They're modest enough from the front." She perked up. "Plus now that Mom and Dad have taken off traveling for the summer, it's kind of the best time to try some more risque stuff out."

"You're crazy," I said.

"I'm scientifically minded," she countered.

"The Venn diagram overlaps on occasion," I said.

"Hehe, good one," she said without a hint of taking it personally. "Ooh, by the way, check these out."

I looked warily at her phone as she scrolled through a few pictures for me.

"Are these... are these just all pictures of your friends' butts?" I asked.

"In tight shorts, yeah," Nova said. "Whose is the cutest, you think? I know who I'd pick, but I want an unbiased opinion."

"This is weird, Nov," I said. "But you really want to know?"

"Of course. That's why I asked."

"Your butt is the cutest," I said.

"That's cheating!" Nova protested. "I asked about the pics."

I ignored her. I could see how obviously pleased she was with my answer. The way she beamed, the happy blush on her cheeks. The way she immediately flipped to a different page in her notebook and gleefully wrote down something she wasn't about to share with me.

Unless it was my imagination, Nova even arched her back a little more, gracing me with an ever so slightly better view of her booty while she scribbled hasty notes to herself. She was killing me, but in such a fun and thoughtful way.

"You know the danger here is I'm going to start checking out your butt more often," I said. "You're training me to misbehave."

Again I was dead positive that Nova was thrilled to hear that.

"Not my fault," she said. "But if you could possibly keep track of how often you feel that way, what I'm wearing and doing at the time, how long your gaze lingers, what--"

"I'm not doing that," I said.

Nova expressed mild frustration with that response. "Kind of a waste if we're not collecting data, don't you think?"

I tilted my head and stared thoughtfully at my sister's cute little booty. "I don't think it's a waste."

She wiggled her hips in response. "You're enjoying looking?"

"Yeah."

Nova nodded like I'd just given her an opinion on something totally innocuous. "I can work with that, I think. I can still take notes, I'd just need to know when you're looking or interested. Some way of recording what's happening."

Her gaze fell to my crotch, which all of a sudden made me embarrassed. Yes, I was getting kind of hard. Not like fully erect over my little sister or anything, but certainly having a reaction to her perfect booty.

"Don't make a note of that please," I sighed.

Nova grinned and scribbled something down anyway.

"You're going to make this weird," I said.

"You got hard," she chirped. "Not me."

"Only a little," I protested weakly.

She tapped her pen on her chin. "Can I see?"

"No."

"Please?"

"Absolutely not."

Nova turned her big, pleading eyes on me. "Even just through your underwear? It's just hard to see what's going on while you're wearing pants."

"I think that's by design," I said.

"You're making this difficult," she grumbled.

"I'm really not," I said.

Nova retreated into her thoughts, with the occasional moment of jotting something else down in her notes. I was honestly curious just what exactly she was keeping track of in there, and how much help it was actually going to be to her. To me it only made sense that something looked good or it didn't. Trying to quantify arbitrary things felt like it would be very difficult or impossible.

I played on my phone, relaxing into just sharing a room with my sister while she did her own thing. It was nice just to hang out sometimes. I could almost forget what she--

"What if I touch it?" Nova asked.

And there it was again. "No," I said.

"Without looking I mean," she clarified, as though it made all the difference.

"Still no," I said.

"Over the pants?"

"Sure."

"Really?!"

"No."

"Mean!" Nova said.

I could see her pouty face from the corner of my eye, but stayed focused on my phone.

She tried a few more angles, and it actually got pretty amusing what she'd suggest, and how increasingly exasperated she got with my refusals. There was, too, something flattering about my dick being so desired, even given the current context.

I had to admit, she got me good in the end. She shifted around in my bed quite oddly, almost like she was throwing a quiet and delicate tantrum. It wasn't that, but I had no idea what she was actually doing until she took my hand and placed it on her butt. The way she'd maneuvered her body suddenly made sense, but very little else did.

I froze, hand firmly on my little sister's ass. Her tiny, skintight shorts weren't hiding much from my touch. I could feel her pretty well, and... it was nice. Really, really nice.

"Feel free to provide any thoughts or feelings you're experiencing right now," Nova said, almost casually, but with a faint hitch in her voice that I almost missed.

"There's something not normal about you," I said.

"I mean in regard to your hand on my butt," she clarified.

"My statement is quite related to that, actually."

But I wasn't pulling away. I didn't want to. I hadn't ever wanted to fight too hard about her wanting me to check out her butt, for instance. I was even less inclined to argue about feeling it up.

She was going to let me do it, too. I could shift my hand and fingers, squeeze her ass, explore the fascinating curves, and Nova would absolutely just lie there and take notes on the experience.

At first I told myself I was just going play chicken with her. See how long and how far she'd actually let me go before she realized this was crazy. But I knew right from the start that was a lie. I knew my sister way too well for that. Not that she'd ever encouraged me to feel her up before. But if she wanted it now, it wasn't likely at all that she'd change her mind.

"You've got a great butt," I finally told Nova.

I could practically see the beaming grin on her face even with her looking mostly away from me.

"Noted," she said, happily marking that down. "Anything more specific?"

"Not that I'd care to try and elaborate on," I said.

"Sometimes I worry you don't have the true soul of a scientist," Nova said.

"I'm excellent at physics and engineering, thank you very much," I said. "Your niche applications of biology and psychology are not my strength."

Nova snickered. "Fair. Ok, let me gather some more data then."

I knew she was going to try something outrageous. Once again, I knew my sister pretty well. She had a face like she knew she was about to get away with something that she knew she shouldn't.

She went for my pants. I wasn't as surprised as I probably should have been. More fucked up was I didn't feel like stopping her. If she'd asked I'd have told her no again. Since she didn't...

I didn't know what to make of the implications there. I shouldn't be more open to things she didn't ask for. Yet much like placing my hand on her ass, just doing the thing was getting easier acceptance from me.

"Ooh, very hard," Nova cooed excitedly. "Lift your butt for a sec, let me pull your pants out of the way."

"Terrible idea," I said, even as I complied.

I knew she was going to pull my cock out of my boxers too. I still could have stopped her. I didn't.

"Oh that's nice," Nova breathed as she got my full erection out. "Fully hard, yeah?"

I nodded. "Yeah," I said, sounding a bit strangled even to myself.

Her fingers felt so good on me. Her touch was not something I should have felt. Not like that. But she had me right where she wanted me, interested and compliant. I knew I was weak like that when I got horny, I just hadn't realized that it would even work for my baby sis.

"See this is what I'm talking about," she said, running her fingertips up and down my shaft. "This is valuable information. If I can do this to you, I'm onto something.

"If you can touch me inappropriately?"

"No, silly. If I can make you hard like this. And..." Nova's eyes widened and she rubbed her thumb over the head of my cock. "And if I can make you drip like that," she finished huskily.

"Yeah, I mean precum's gonna happen if you play with me like that," I said, failing to sound as casual as I would have liked.

Nova bit her lip and kept rubbing me, delighting in each fresh bead of precum she milked from me.

"Useful information," she muttered. She seemed to be trying to convince herself as much as me.

Nova dragged her notebook over to where she could jot notes with her right hand while her left settled into a slow stroking motion intermixed with teasing the tip of my cock and greedily swiping up precum.

It was a bizarre and confusing experience for me, but one that felt incredible.

"You know you're jerking your brother off," I said in a low voice.

Nova started and glanced at me as though she'd half-forgotten I was there. She slowly grinned. "Not yet I'm not." She hesitated. "I haven't really done that though. Is it ok to practice?"

"You're... you're seriously asking that while you've already got your hand wrapped around me?" I asked.

She cocked her head, and the impish sparkle I saw in my sister's eye was not at all one of scientific detachment. "Would you like me to jerk you off?"

"Nov..."

"Sol."

I wasn't going to win a battle of wills here. It wasn't fair at all when she was still running her hand slowly up and down my cock. I still waited and let the tension build, just to salvage some kind of pride.

"Please," I finally said. "Please jerk me off."

It might as well have been my sister's birthday for how gleeful she looked. It wasn't about the handjob itself, I was well aware of that. Probably some combination of the power she had over me right now, and the information she'd gleaned about how I operated.

"That's something to explore again," Nova mused, writing her notes before focusing on my cock again.

"What's that?" I asked, hardly daring to voice the question.

"How horny you have to be to ask me something like that," she said. "From your sister of all people."

My cock twitched and spurted extra precum in her hand. She gasped and giggled and wrote it all down of course.

"Oh my god," Nova squealed. "Really?"

"Shut up! It's not a fair test," I insisted.

"Uh huh," she said, stroking me with more purpose. She gazed at me intently, waiting patiently, her eyes piercing through me. "But this is rather fascinating all the same, don't you think? And it calls my data into question if you're going to respond so positively to your sis-ter playing with you like this."

My cock twitched again in her warm little hand. I couldn't do anything about it. I had no control. She was going to think I was some kind of total perv at this rate.

"I don't think about you that way," I mumbled, face flushing embarrassingly warm. "This is not normal."

"I could almost believe that," Nova said thoughtfully. "But I also believe now that more testing is in fact required here. Because you do react to the incestuous component, even if as you claim that's not usual. Kind of a bad bro-ther, aren't you?"

I moaned helplessly as Nova kept up her sensual torment. I wished it wasn't so hot when she reiterated our sibling status, but it actually fucking was. Her stupid games, her stupid tests, they were doing things to me. Of course they were. I'd have a reaction to any girl in bed making me check her out, grab her ass, and lie back while she played with my cock.

But yes, there was some specific thing about her being my sister. I'd only be lying to myself to keep pretending otherwise. I just didn't like it. It was embarrassing.

It wouldn't have even been so bad maybe if she'd been a hot older sister. Even a sexy mom. Those could have been excusable. Getting this way for a cute and mischievous little sis reflected poorly on me, I felt.

But I couldn't stop her stroking me. I didn't want it to end. She felt so good. So good. My baby sis's handjob...

"I don't want to spoil the result," Nova said softly, "but then again I didn't think to time it properly anyway this time. I think you should cum for me, Sol. Do you want to cum?"

I whimpered. "Yesss."

"Good. Then cum for me, ok?" Nova was feeling the horniness of it all too. I knew she was. But she was still very much in charge. She smiled wickedly at me. "Cum for your sis-ter?"

I did, I came for her. Exploded and made a mess all over myself and her hand. She kept stroking me, giggling madly at the hot cum getting on her, but not letting it stop her. I had to eventually nudge her hand away when my orgasm was well and truly done with.

Nova stared at the cum on her fingers, and only slowly and absently fumbled for her notebook. I had no idea what she still felt she needed to record from this event, but she was dedicated, I had to give her that.

"That was... useful," Nova said, hesitating like she'd temporarily forgotten how to speak.

"It felt really nice," I said.

"Yeah?"

"Yeah."

"You think other boys would like it too?" Nova asked.

"Is that a serious question?" I asked.

"Yes, of course."

I laughed and shook my head. "I can't with you right now. But like, maybe if you jerk a boy off, don't follow up with asking about what other boys might enjoy."

Nova nodded seriously and started writing again.

"Don't write that down," I sighed. "Oh nevermind. You're not going to listen, are you?"

"I serve a higher calling," she informed me.

"I don't know that handjobs are a higher calling," I said. "Although I suppose that's a religion I could get behind."

"Not that kind of higher calling, silly," Nova said. "Now if you'll excuse me."

I watched my sister patter out, somehow still glued to her cute, tight little booty even after cumming.

"I wasn't keeping you here," I muttered after her. Though in fact some twinging part of me wanted her to stay. I was not about to admit to such things right now. She'd only write it down, probably.

****

Nova didn't do anything weird for the rest of the week. Instead of relief, or indeed indifference, I found myself fantasizing about her butt and thinking about the feel of her soft hands on me while I was jerking off. That wasn't good. She'd be so smug if she knew.

It was probably for the best if that event had been a one-time, crazy thing anyway. It wasn't like incestuous handjobs were encouraged in society. Even if they did feel really good.

I didn't think anything of Nova inviting Skye, one of her best friends, over. That was a perfectly normal thing. I liked Skye well enough, as far as my sister's friends went. She was relatively fun and polite.

She also had a cute butt, as I slowly realized. I may not have really looked before, and perhaps it was due to Nova putting my mind onto this sort of thing. After checking out my sister's butt, checking out her friend was a step more behaved if anything.

It took embarrassingly long for it to dawn on me that this was a deliberate thing. Skye was wearing small, tight shorts, very similar to the ones Nova wore so often these days. Very unlike her usual. And the way she kept blushing and smiling around me kind of confirmed that something was up.

It was all so obvious once it clicked. This was Nova experimenting on me again. She didn't actively write in her notebook where I could see, but I was sure she was doing so. I wondered belatedly if Skye had been in those butt photos my sister had tried to get me rate previously. Most likely she would have been.

I took an opportunity when Nova wasn't in earshot to question Skye about the situation.

"You know what Nova's up to, yeah?" I said.

Skye flushed and wouldn't quite meet my eye. "What do you mean?"

"With the shorts and all. In front of me."

Skye squirmed. "She said you'd like it," she finally said, blushing even more furiously red than before.

"She's not wrong," I said. "You've got a cute butt."

I thought Skye might just melt away right there. More than just her butt was cute, as it turned out. The freedom to notice these things was kind of fun.

"Really?" she squeaked.

"Yeah," I said. "So you want me to check it out, huh?"

"Um... well Nova wanted to experiment with that," Skye said evasively. "See what you'd do..."

"And what do you want?" I asked.

Skye looked away and wouldn't answer.

"Do you just want to see what I do?" I prodded gently.

She nodded. "Nova said it would probably be fun. And it wouldn't be a big deal, because you know, you're her brother. It's just... you know, learning. Science. Figuring stuff out."

"Yeah, right. Science," I said.

I shifted beside Skye and let my hand drop to her butt. She whimpered and didn't seem to know what to do. She very much didn't pull away though.

She slowly untensed, and perhaps even pushed back against my touch. She didn't seem to know what to do with herself, but she was here for the fondling.

I took Skye to the couch and sat down. I let her curl up with me in a way that left her butt sticking out where I could freely grope it some more.

Nova materialized almost immediately after Skye and I had settled in. She was so subtle I didn't even register her presence at first until I heard the scratching of her writing in her notebook.

"Don't let me distract you," Nova said as I turned my gaze toward her. "Just keep doing your thing."

"You're actually insane," I informed her, knowing I might as well hurl insults at the ocean for all the good it would do.

"Genius and insanity are often conflated," Nova responded primly. "How would you say Skye's butt feels compared to mine?"

So she'd shared that part with Skye already. Somehow I'd suspected she would have, even though anyone else probably would have been more secretive about getting felt up by her brother.

"I don't know how to answer that," I said. "Nor am I sure I want to."

Nova sighed. "You're exasperating sometimes, you know that? If you need to compare directly, you can just ask."

It wasn't what I was angling for, actually, but maybe I should have been. Nova curled up with me on my other side and made sure I was able to fully cup and squeeze her ass as well. Getting sandwiched between the two girls with freedom to feel up their butts all I wanted was cozy and delightful.

Nova jotted down notes intermittently--while making sure I couldn't see what she was writing of course--and seemed totally at ease with letting her brother grab her butt in front of her friend. Skye remained cute and shy about the whole thing, though admittedly didn't seem any more bothered about me groping my sister than Nova herself was.

"So which do you prefer?" Nova eventually asked. "And how significantly would you say the incestuousness impacts your decision?"

"Has she always been this way and I just haven't noticed?" I asked Skye, ignoring my sister.

Skye shrugged. "A little bit. She's been different lately with trying to figure out how to quantify and acquire hotness."

"It's a valuable commodity in today's market," Nova said. "And useful research in any case. My butt or Skye's?"

I sighed. "It's still hard to actually pick, you know. There is a thrill to you being my sister, but also a novelty to Skye since I haven't felt her before."

"Hm, equivocating still, but actually a good point," Nova said, wrinkling her nose cutely in thought. "Too many variables is part of the problem, I think."

"I also kind of don't want to say the wrong thing or possibly answer at all," I said, "lest I lose access."

Skye giggled and clung tighter to me. I wondered if she had some sort of crush on me that was having a chance to be explored now. Or maybe, like Nova, I just represented a relatively safe person to try some stuff out with and she was enjoying herself underneath her embarrassment.

Even Nova seemed to enjoy my admission, though it thwarted her research.

"Engaged in thoughts and actions to acquire more time with our booties," Nova said thoughtfully. "That's good actually. Maybe I need to start being less direct in my questions." She looked at Skye. "Looking at the things Sol desires or asks for might get us better data than asking him to rate experiences. He hasn't been great at that so far."

I frowned and pinched Nova's butt pretty hard. She yelped and pouted at me while Skye just giggled some more. Skye seemed to be just having a nice time without all the distraction that Nova was providing herself.

Nova retaliated by pressing her hand firmly against my crotch, catching me off-guard and making me gasp at the sudden pressure.

"And that," Nova said gleefully. "Can't equivocate out of these erections so much, huh?"

Skye's eyes went wide. "He's hard."

"Yeah," Nova said, rubbing my cock through my jeans. "Check this out."

My sister worked my pants open and pulled them down, apparently not feeling the need to ask me first. She and Skye both stared fixedly at my cock, and Nova was more delicate about tugging my boxers out of the way too, unveiling me properly.

"Oh, he's very hard," Skye said breathily.

"Yeah," Nova said, grazing my shaft with her fingers. "It's pretty fun when Sol's like this." She bit her lip. "At least, that's been my limited experience so far."

"You really... really did this before?" Skye asked.

Nova nodded. "I told you."

"Yeah but... your brother," Skye squeaked.

"I think he likes it," Nova said conversationally. "He likes his little sister touching him, don't you Sol?"

My cock betrayed me again with an obvious twitch as Nova teased me.

Nova laughed. "I get much more direct results from this," she said, lightly grabbing my cock. "Want to see how long it takes him to cum?"

Skye grinned shyly and nodded.

Nova gazed at me with false innocence. "Would you like that, big brother? You want to see if your sis-ter can make you cum again?"

I groaned and squeezed her ass hard. "Don't say it like that."

"But you're so twitchy and precummy," Nova taunted. "You liiike it."

She stroked me up and down, enough to feel good and keep me from protesting. She very obviously delighted in the reactions she got from me, and I could see her filing them away to be written down when she had her hands free again.

I kept feeling her and Skye's asses while she jerked me off. Nova was only teasing me yet, but still felt great and got plenty of reaction from my cock.

Skye was entranced, watching Nova play with me even more closely than I was. I didn't think she realized how interested and horny she appeared just then.

"How badly do you want me to take care of this?" Nova asked, and I could hear in her voice that it wasn't all just scientific interest.

I hesitated, not wanting to move, but feeling like we probably should.

"Let's... go to my room," I suggested.

Skye's eyes widened like the idea shocked her, but she didn't disagree.

Nova considered thoughtfully, then nodded.

We ended up in my bed, my pants totally off, the two girls lying down facing my cock. Nova had her notebook with her and scribbled in it before returning her hand to me.

Without making any kind of deal of it, Nova scooted herself around to make sure I could reach her butt while she stroked me. I accepted the offer.

"This is the experiment for today?" I asked.

"Yeah," Nova said.

"Two girls?"

"Changes things, doesn't it?"

I eyed Nova's butt, then Skye's. "It does," I agreed. "Shouldn't you give her a turn too though? You know, for science?"

Nova twitched back, hand leaving me. "Oh, right," she said. "That's true, you should try for a bit, Skye. I need to keep notes anyway."

Nova appeared slightly disappointed to release me, though that may have been wishful thinking. Skye looked excited but nervous.

"How do I..." Skye said.

"Just grab him and move your hand," Nova said. "I made him cum pretty easily last time."

Skye giggled with nerves and interest as she took hold of me. "Must be nice having a brother to let you try stuff on."

"This is a new thing," I said, feeling the need to make that known. "Usually this doesn't happen."

"Oh," Skye said, already enthralled by my cock again as she moved her hand up and down. "Too bad."

I looked at Nova, but she was no help. The two of them had such a warped view of things all of a sudden. Or maybe they had for a while, for all I knew.

And yet... here I was letting my sister and her friend play with me, experiment on me, and I was enjoying it. Enjoying it way too much. So what did that make of me in comparison?

"Don't you have a brother?" I asked Skye.

She blushed, but for some reason tightened her grip on my cock.

"Yeah," Skye said. "But not one who'd let me do this. Nova's lucky."

Nova got the faintest of self-satisfied smirks on her lips. I wouldn't have even noticed if I didn't know her so well.

"I might be kind of lucky too," I admitted.

Nova's smile grew more prominent. "You do enjoy this, don't you," she said.

"I think you know I do," I said.

"I do," my sister said. "It's nice to hear you say it. In detail, when possible."

"Right," I said. "The data."

"The data," Nova confirmed.

"But arguably," I said, "if you and Skye are going to be letting me feel you up and jerking me off until you have enough data, I might be better served by withholding."

Nova nodded seriously and noted something down. "Attempting to prolong the experiment. So you're quite into it now. Would you say it's more fun with more than one partner at once?"

I glanced at Skye. "I might say that," I said. "Probably... probably we need to try more times with just you, and with both of you. You know, to really compare."

They both seemed pleased with that idea. Which was crazy. The reality of being able to suggest something as ludicrous as that and get positive reception for it was brand new to me, and likely to go to my head at this rate.

I kept squeezing Nova's butt as Skye jerked me closer and closer to completion. All three of us were blushing and flustered, and all trying to hold it together as best we could. I even caught Nova forgetting her notes at times and just staring at my cock with a hungry expression, though she'd eventually remember she was meant to be researching.

"You're gonna make me..." I moaned.

Skye's eyes flashed. "Are you?" she asked breathily.

I nodded.

"Good, good," Nova said. "Keep stroking. Make the cum come out."

Skye nodded seriously, and her tongue poked out the corner of her lips rather cutely as she kept focus on getting me off.

She got even cuter when cum erupted around her fingers, making a mess everywhere. Skye squealed and giggled, but kept milking out more cum until I was spent.

Nova delightedly noted it all down, including sticking her fingers in some of the mess and rubbing my cum thoughtfully around like she could determine useful information from its consistency.

"Thanks Skye," I said. "That was nice."

Skye beamed shyly. "I did ok?"

"Yeah of course," I said. "I came, didn't I?"

"I don't really do a lot of this stuff," she said. "It was... easier than I thought. And kinda fun."

"It is, isn't it?" Nova said. "I was kind of worried too, but it's not such a big deal. At least with Sol. He makes things pretty easy once he stops being stubborn."

I pinched Nova's butt, making her yelp and glare.

"A certain hesitation toward being inappropriate with my little sister is not being stubborn," I insisted.

"It's not inappropriate if it's for science," Nova said. "It's not like it's actual incest."

Skye giggled at the word 'incest,' as though that was funnier and more scandalous than the actual sisterly seduction she'd already been witness to. I had to worry slightly about the two of them.

"I think it might still be, actually," I said.

Nova cocked her head. "Well in that case I think you're into it."

"I mean, I wouldn't say that," I protested.

My sweet, considerate sister stared at me a moment, almost issuing a challenge with her eyes, then reached out and grabbed my cock. It was soft and messy with cum, but she played with it and had it filling her hand back out in no time.

"You sure about that?" Nova asked. "You don't like when your baby sis-ter does this stuff to you?"

I whimpered rather embarrassingly. I wanted to be able to tell her to stop. To not fall for her tricks, but part of me was already noting how easy it was to get her to put her hand back on me. I didn't even need another cum right now, and yet I fully was on board within seconds.

"Maybe it's nice," I hedged.

Nova scooted around to lie between my legs and watch me while she played with my cock. "Maybe it's nice? You can do better than that."

She had me there. Now that she had me going again, I was hesitant to argue and make her change her mind. Not that I thought she would.

Skye had jerked me off, which in some undefinable way made me feel like Nova had something to prove now, I just wasn't sure to whom exactly. But she wanted to make me cum too. I was sure of that. I wanted it as well.

"Your hand feels really good," I said, giving Nova what she wanted, but not stopping there. "Your hand feels really good on your bro-ther's cock."

Nova made a small, helpless noise and ducked her face away from eye contact. She liked me saying that more than she wanted to admit. I knew the feeling.

"Such a good sister," I added.

Nova growled in her throat, either annoyed or horny, or most likely both. She kept stroking me, not faltering.

My second handjob of the session felt very good and not nearly as urgent since I'd cummed already. I wanted to enjoy this. I didn't have either girl's butt in easy grabbing range, but I was able to snake my hand around Skye's waist and pull her back toward me.

Skye was shy about being moved closer, but made herself comfortable against me while we both watched Nova. I let my hand wander up her shirt, waiting to see if she'd protest. She didn't. She even moaned softly as I got to her tits.

"You like having something to play with," Nova said, not making it a question.

"I could say the same of you," I said.

"This is not the same," Nova said. "This is research. For a purpose."

"Tell me you aren't enjoying it though," I challenged her.

"Oh whatever," Nova said. "Just shush. Let me focus."

I grinned at her even though she had her head down, staring at my cock as her hand moved up and down my shaft. She was enjoying herself. That made it better as far as I was concerned. It was more fun if everybody was having a good time.

Skye was getting very squirmy the more I played with her tits. She kept squeezing her thighs together, or reaching down with a stray hand before catching herself. It was exciting to think that she wanted to masturbate but didn't actually dare.

It was subtler, and I almost didn't catch it, but Nova's hips were going too. It was only a small motion, but she was definitely grinding against the bed as she stroked me. My sister getting horny from teasing me and playing with my cock. It was delightfully fucked up.

"Do you want to touch yourself?" I eventually asked Skye, once I'd built up the nerve to broach the subject.

She gasped and squirmed in my arm. "I don't know. Maybe."

Nova grinned and pretended to ignore the exchange.

"Do you want me to touch you?" I asked, pushing further.

Skye whimpered and looked to my sister for help.

Nova smirked at Skye. "Well, do you?"

"That... that wouldn't be ok, would it?" Skye asked.

"I'm into it," I said.

"Nov?" Skye asked. "He's your brother..."

Like Nova had exclusive claim to me because of our sibling status. Then again, that was weirdly fucking hot to think of actually.

Nova, running her thumb back and forth over the precum at the tip of my cock, gave it some thought.

"It wasn't the way I expected today's research to go," Nova said. "But that sounds like it could be quite interesting. Try to remember details for me later, ok? I don't feel like anyone's going to be taking useful notes for a bit."

Skye nodded, shy but eager. I let my hand drop experimentally from her tits to her tummy, then down across the front of her shorts. She pressed against my touch, sighing contentedly at the contact.

"Take your shorts off," I said.

Skye blushed, but wriggled out of her shorts for me, leaving her in some rather soaked panties.

Nova watched, curious and interested. The handjob she was giving me had truly become her just playing with me. No real attempt at getting me off. It was a pleasant feeling that would eventually be too much, but for now was enjoyable and keeping me horny enough to push my luck.

I rubbed Skye over her sodden panties, reveling in the small noises and involuntary movements I got from her. I didn't have a plan to start with other than that. Just rub her and see what happened.

We made a twisted and beautiful tableau, I thought. Trying things out, finding out what felt good, enjoying each other. Not exactly what my sister had intended, but all deriving from her inquiries in some fashion. If she'd wanted to experiment with sexual attraction and interest, this was certainly a good result for her.

I still thought things were simpler than she made them out to be, and sometimes things just happened the way they happened, without data and trial runs to back them up. Then again, maybe things happened because of her strategically getting me horny in the first place. Something to consider.

Skye moaned louder as I slipped my fingers under her panties. It seemed like she was happy for me to have free rein with her pussy right now, at least with my hand. More than that would probably be excessive, probably would mess with the casual sexual energy of the room. But fingering her was very on.

"Are you enjoying yourselves?" Nova asked in a mildly amused tone.

"Of course," I said, adding a little moan as my sister gave a flourish of her hand over the tip of my cock, then stroked back down again.

Skye whimpered cutely and nodded.

"That's good," Nova said. "Because I want you to cum, Sol. Cum for your sister." She bit her lip. "And Skye, if you cum, that's going to be interesting too."

Skye nodded even more eagerly. She wanted to. I wanted her to as well.

"What if you tried licking it?" I asked Nova.

She cocked her head. "Oh really?"

"Well... just to test it," I said.

"Uh huh. You want your sis-ter to put her mouth on your cock, huh?"

I groaned and twitched in Nova's hand. "You gotta stop saying things like that," I protested.

"You liiike it," Nova teased.

"I think you like that I like it," I countered.

She shrugged. "It's kinda fun."

Nova kept jerking me off, then eventually did lean down and swipe her tongue up my shaft. Perking up at the way I moaned for her, she did it again, and again. Giving me licks in between stroking me, or flicking her tongue across my precummy tip while jerking me firmly.

"Cum on her," Skye urged, whispering in my ear. "Do it."

I closed my eyes, nodding, then opened them again, watching my sister directly. I was close. So close. And Nova was absolutely intent on making me cum. There was something insanely hot about that, even outside of just the physical sensations.

My first spurt of cum caught Nova across her tongue and chin. She stayed frozen for long enough to get a second shot, then pulled back and let the rest of the mess fall on me and her fingers.

"You... came on me," Nova said, sounding somewhat dazed.

"That was bound to happen," I said.

Nova gave a small, secretive smile and reached for her notebook. I tried not to sigh out loud about it, but honestly she'd made me feel so good that whatever she felt she needed to do right now was probably well earned.

"Oh god," Skye whispered. "Oh wow, oh god."

My fingers had been probing inside her, as well as rubbing around her clit on the outside. Skye pushed my fingers a little deeper into her, held them there to make sure I wouldn't move, then started rubbing her clit for herself. I let her use me as a prop while she got herself off, apparently quite turned on by me cumming on my little sister's face.

Nova noted some things down and then, I could only assume, started taking some observations on Skye's journey toward orgasm. That went in a different section of the notebook. I had no idea what it was for, but then again this was all my sister's unique brand of research in the first place. It could be for anything.

Skye panted softly after getting herself off and curled up against me, nestling as cozily as if we'd cuddled many times before rather than being recent strangers to any sort of intimacy with each other.

"This," Nova said, flipping slowly through her notes, "has been a productive day."

I snorted. "That's one word for it."

"You disagree?"

"No. Just... what if you used words like fun or intense or horny?" I asked.

Nova nodded agreeably. "Those are pertinent choices also."

She looked down at her hand, seemingly recalling the cum on it for the first time since it had landed on her. She touched her face as well, then experimentally licked at the cum on her fingers. After a moment's hesitation, she tasted some more.

"Not bad," Nova decided, noting this down as well. "Not amazing, but not bad."

"Pretty hot though," I told her.

She paused. "You find that enticing?"

"Yes," I confirmed.

Nova grinned. "Thank you. All I'm asking for is some data to work with here and there."

Skye giggled softly. "What about you, Nov? Did any of that get you horny?"

Nova actually blushed this time and didn't answer straight away.

"It did, didn't it?" I teased.

"Maybe some," Nova said defensively. "Don't worry, I'm recording that as well."

She wouldn't quite look at me, and she was pretty fidgety.

"Should we, perhaps, make you cum now too?" I inquired, trying to sound casual about it.

As calmly as I spoke, it still flustered Nova. She didn't seem to know how to proceed, which was both fair and incredibly cute.

"That might be nice," Nova finally said. "You... you want to?"

I smiled. "Yeah."

"Get Sol to put his fingers in you," Skye advised, still clinging to me. "It feels really good." She started to reluctantly pull away from me, but I held her where she was, which she happily accepted.

Nova took her shorts off a bit shyly, revealing panties every bit as soaked as Skye's had been, if not more so. I marveled in awe at how they clung to my sister's pussy, showing off the shape of it even if I couldn't see it directly.

She crawled forward, finding an appropriate spot next to me, and guided my free hand into her panties. She was so wet and needy, and moaned as I rubbed her wet little cooch.

I kept rubbing Nova until she urged me to press my fingers inside her and she started rubbing her clit, much as Skye had shortly before. It was different, of course, having fingers inside my sister like that. Different and more intense.

"That's right," I urged gently. "Cum for me. Cum for your bro-ther."

Nova whined and shook her head, flustered. But she panted louder and her fingers blurred faster. I wasn't the only one who got a thrill out of the sibling aspect of this. She most likely didn't want to admit to it any more than I did, but when we got horny enough there really wasn't any hiding it. It was at least more balanced if it worked for both of us.

"You two are crazy," Skye whispered. She bit her lip. "But that's really hot too."

Nova whimpered and rubbed herself, and eventually came moments later. I watched all the tension and need drain out of her in a relaxing and satisfying way, and my sister nodded like she'd done a good job that needed doing.

She leaned back against me afterward. Unlike Skye, all curled up with me, Nova had her back to me, and had her legs up to rest her notebook on. She still let me hold her with my arm around her and my hand up her shirt on her tummy, but her focus was on taking notes again.

"Make sure you write down that you get turned on playing with your brother," I teased her.

Nova snorted in exasperation. "This isn't about me. And anyway, that was only because it caught me by surprise."

"Maybe it should be about you," I said. "Seems wasteful figuring out how to get someone interested and excited and ignore what you actually want, doesn't it?"

Nova hesitated. "I suppose that's true. No good doing all the work for someone who doesn't do it for me."

"It's a good point," Skye murmured, happy and sleepy on my shoulder. "Gotta find the right boy first, then worry about how to get him."

"Ugh, so complicated," Nova complained, starting a brand new section in her notes. "How does anyone ever figure everything out?"

"I think mostly they don't," I said.

"Well that seems chaotic and painful," Nova said.

"Yeah," I said. "That sounds about right." I shrugged. "My experience dating has been chaotic and painful, mostly."

"See? So acquiring knowledge and experience is needed first," Nova insisted. "So we can be more deliberate and resourceful."

I slid my hand up to grab my sister's tit. "Or just see what happens and slowly figure out what works and doesn't work," I suggested.

Nova blushed and moved her arm to trap my hand where it was on her chest. "Sloppy research, you mean. No thanks. I'll do it my way."

I ran the fingers of my other hand up and down Skye's spine. She purred softly, eyes even closed now as she cuddled against me.

"I suppose I can live with that," I offered magnanimously.

"Me too," Skye mumbled cozily.

"Good," Nova said seriously. "I have lots of pages to fill yet." She paused. "Might need a bigger book, even."

****

The next night, as I was getting ready for bed, Nova slipped into my room. She paused at seeing me with my shirt just pulled off, but then padded over to sit on the edge of my bed, ever-present notebook in hand. She wore a loose sleep shirt with bare legs underneath.

"Did you masturbate today?" Nova asked.

"Your small talk needs work," I told her.

She said nothing.

I sighed. "No. I was probably going to before bed. Helps me sleep, you know?"

Nova nodded. "Makes sense. I find that too. But I kind of realized I might get better data if you masturbate less. Or not at all. So we know when you get horny, and how much stimulation and release you're looking for, and how that impacts your interest in me. Stuff like that."

"My interest in you, huh?" I said.

"In girls I mean," Nova said, looking away quickly. "Just, you know, with me for now. While we're researching."

"You enjoy how turned on the 'sister' thing gets me though," I said.

"Yeah well... it's funny, isn't it?" Nova said. "And it's very possible that some other cute and interesting boy might like that kind of stuff too at some point, so it's not like it's without value."

"Ah, very sensible," I said, meaning nothing of the sort. "Do you have panties on under that shirt?"

Nova cocked her head curiously at the sudden shift in conversation. "None of your business actually," she grinned.

"Ha, fine. I think you like that your bro-ther is interested in messing around with you though," I said.

"Sol!" Nova protested. "Behave."

I shrugged. "Why?"

I sat next to my sister and let my hand slip under her shirt. She had panties on. It would have been quite a leap for to have gone without, but I admitted a small disappointment about it all the same. Nova was really throwing me for a loop lately. Going from purely platonic baby sister to someone I hoped would visit me without any panties on.

Nova was flushed though. Her cheeks red, and her skin warm under her shirt.

"Not all the data can be about sibling kinks," Nova said, almost sounding like she believed herself. "That's only going to get me so far with attracting a boyfriend."

"But you do have that kink," I pressed.

"You really want to get into which of us has it worse?" Nova asked. "It doesn't reflect well on either of us, in some ways."

I mulled that over. "Perhaps," I said. "But it doesn't mean anything, right? And not like anyone has to know."

"Skye knows," Nova said.

"Well yeah, but--"

"And Aurora."

"Aurora! How many of your friends are you--"

"Just them," Nova said placatingly. "We've been trying to figure stuff out together. Sharing information and stuff. No one teaches you how to attract the right sort of boys, you know. To find someone who likes you and will treat you well. We're just helping each other out."

"I mean right now you're just learning how to seduce your brother," I said. "Which I appreciate, but it feels like you're limiting yourself."

Nova shook her head. "No, see, this is perfect. You're not someone who's going to be a problem long term. Just someone to mess around with for a while. And I know you, and know that you will treat me well, and be kind to my friends for that matter. And if I can even get my brother to like me in a sexual way... that feels quite promising."

"Are you... using me?" I asked. "Am I being used?"

"Kinda, yeah. Do you mind?"

"Are you going to jerk me off before bed?"

"Hopefully," Nova said.

"Then I think maybe I don't mind," I said.

I got into bed with Nova, hesitating only a little about getting fully naked. It wasn't like having a shirt or not made a big difference, but the weight of full nudity with my sister still meant something. Once she got cozy next to me it all felt good anyway.

"There's an argument, I suppose," Nova mused as she played with my cock and got it hard, "that if you make this too easy for me I won't really learn as much."

"Maybe the lesson is things aren't as difficult and complicated as you think they are," I said.

"Actually possible," Nova conceded. "But the data doesn't back that up so far."

I moaned quietly as my little sister's soft, warm hand stroked softly up and down my cock.

"We better do more research then," I said.

"See? Now you're getting it."

Nova jerked me off while snuggled up against me. She seemed happy where she was, and I was happy to have her there. It got me thinking about removing her clothes though.

I settled for slowly working my hand under her shirt. The way she lay on my arm restricted my movement and options, but Nova just smiled as I put my hand on the small of her back or toyed with the edge of her panties.

"This is nice," she finally said.

"Agreed," I said.

"You know, I was worried sex stuff was going to be horrible and stressful," Nova said.

"Were you really?" I asked.

"Well... maybe not horrible. I knew it could feel nice. But stressful, sure." Nova lay her head more on my chest and watched her own hand moving on my cock. "But this is just... comfortable. Pleasant."

"It could be more exciting if you wanted," I said.

"Hehe, I'm sure it could. But no, not right now. I'm enjoying this." Nova looked at me. "It's kinda sexy you being naked though. I might want more of that."

I bit my lip, enjoying the way she gazed into my eyes just then. "You like that, huh?"

Nova shrugged and lay her head back down. "Well, you know, it's easier to try things out."

"You said it was sexy," I said.

She was quiet a moment before replying. "It is," she admitted. "I've never been in bed with a naked boy. I think I like it. You know, if it's the right boy."

"And your big bro happens to be, huh?" I said in a low, teasing voice.

Nova squirmed. "For some purposes, yes."

"You think your brother's sexy."

"Sol! Behave!"

I chuckled. "The sheer irony of you telling me to behave while you're jerking me off."

"Hypocrisy, actually," Nova said.

"Still," I grinned, "you think I'm sexy."

Nova gave me a light bite on my nipple. It was probably meant to chastise and silence me.

"Ah!" I gasped. Then, "do that again?"

Nova buried her face in my chest. "Solll! You're so horny!"

"That's what you wanted," I said.

"Yeah, but..."

Nova nipped at me again. I flinched, giggling at the sensation. I got her back by slipping my hand fully into her panties, grabbing a handful of my sister's ass, then giving her a sneaky pinch.

"Ow, hey!" Nova squealed. "You told me to!"

"I know," I said, daring her with my eyes to do it again.

Nova let go of my cock and pinched my side where I was more sensitive. I laughed and flinched away from her attack. I tried to retaliate, but my little sister was in full dodging mode now, wriggling around out of any attempt at getting hold of her.

We ended up wrestling around together, which held whole new dimensions for the two of us given how sexual things were. Nova was slippery, but not strong enough to really pin me and make it stick. She did, however, pretty quickly realize that she had a new and effective weapon against me, which was to press or rub part of herself against my cock. I couldn't fight against that.

"Are you going to be good?" Nova asked, finally sitting atop me, her cute butt pressed against my erection, slowly grinding back and forth in small but significant motions.

"Define good," I said.

"No pinching me," she replied promptly. "Unless I ask."

I nodded, grinning. "Deal."

Nova nodded back, then bit her lip and leaned down to me. She tugged the collar of her loose shirt away from her neck, baring one of her shoulders.

"Try... just try biting me too," she said. "Just a little."

I nodded and pressed my teeth to my sister's pristine shoulder, nipping at her hard enough to leave a small mark behind. She gasped, thought about it, then leaned closer.

"Again," she urged.

I bit Nova's shoulder again, in a different unblemished spot. She sighed this time and relaxed down on top of me.

"We might need to experiment with that more," she purred.

"I think so," I concurred.

Nova resumed stroking my cock, and I got her panties down to her thighs, taking her ass as my plaything. She bit me a few more times, giggling at my gasps and the way I twitched in her hand every time.

"Cum for your sis-ter," Nova urged me as I got close.

I groaned. She was practically training me to cum to reminders of our sibling bond. She was going to keep doing it too. I could tell.

"You could... just tell me... to cum," I panted.

"You like it more this way," Nova said. "Cumming for your little sis-ter is hotter. Try to tell me it isn't."

I whimpered and shook my head, and seconds later was cumming over my baby sis's hand, just like she wanted. Fuck, it was hotter cumming for her, just like she said. I couldn't pretend it wasn't.

I passed Nova some tissues so she could clean us both up, then she turned on my bedside light, curled up next to me, and thoughtfully jotted down important information in her notebook.

"You're writing down that you like being bit, right?" I said, kissing her shoulder where I'd left marks.

"Of course," Nova said. "You think I'd ignore something like that? I'm shy and inexperienced, not ignorant."

I laughed softly, knowing full well how much more of a sin the latter was to her than... well, most anything else, really.

I nibbled on her shoulder some more, seeing how distracting I could be. I worked my way to her neck, giving her a few calculated bites just to see.

Nova tried to ignore me, to focus on her notes. She got squirmy though, and she went long seconds without writing a thing.

"Play with me?" she finally asked.

"Your pussy?"

"Yeah. You got me all wet now," she said.

"You've been horny for a while," I said.

"Maybe. Just... if you're gonna turn me on like that..."

"Any time," I whispered, moving my hand between Nova's thighs. "You can just ask."

"It's better if I find what turns me on naturally," Nova said. "It's better research than just, you know, asking."

"Well we found that out tonight, didn't we?" I said.

Nova perked up. "Oh yeah, true. We did pretty good tonight, huh?"

"I'd say," I said.

I removed Nova's panties entirely. She didn't let me flip her shirt up, and I still didn't get a direct look at her pussy, but she let me play with her as much as I wanted. She was so wet. Just as horny and flooded as could be.

"Some might say asking for what you think you want is a pretty natural way of finding out what you like," I said thoughtfully as I fingered my baby sister's hot little pussy.

"I wouldn't have thought to ask you to bite me," Nova argued.

"Fair. But you could ask for other stuff," I said.

She shrugged. "We'll see."

I gave up for now. I kind of understood where Nova was coming from. It was hard to know what you liked until it happened.

At least some things were obvious. Like her playing with my cock, or me playing with her pussy.

I was really, really enjoying her pussy. It was fun getting to rub it, and slip fingers inside. Nova made such cute faces and noises as I made her feel good.

I waited until Nova was getting really close to cumming, then gave her an intent look. "Cum for me, Nov. Cum for your bro-ther."

She squirmed. "Solll!"

"Cum for your big brother, ok? Be a good little sister."

"Ah! Too much. Too muuuccch!"

She came on my fingers, making me feel like it wasn't too much at all. I wanted her to cum for me, and she did. It seemed appropriate to me.

"That's too much," Nova repeated, clutching at me afterward.

I rubbed her thigh. "I don't think it was. I think you liked it."

"I did like it," Nova said. "But you're going to think I enjoy the incest part way too much."

"You did kinda start it," I said.

"Well... maybe." Nova bit her lip. "And it is fun. Just don't overdo it."

I grinned at my sister. "Just a little incest as a treat?"

"Hehe, yeah. As a treat."

We rearranged ourselves, getting cozy again with Nova propping herself against me so she could make her notes. I held my arm around her and waited until she let me turn out the light again. She didn't leave for her own bed, and I wouldn't dream of suggesting it. I wasn't prepared to spoon her or anything, but having her next to me was nice.

****

Nova was extra chipper the next day. I thought sleeping in the same bed might be weird afterward, but it felt normal even though it really wasn't.

We didn't end up with much of a chance to hang out that day, and for all I knew my sister wanted a break before being naughty again anyway. I couldn't stop thinking about her though, and sneaked into her bedroom that night instead of just being patient.

"Hey! I was changing," Nova protested as I slipped into her room.

I'd caught her with her shirt off, but bra still on.

"That's ok. I'll wait," I said, hopping into her bed.

"I knew you were going to get to be a nuisance sooner or later," Nova sighed.

I grinned at her. "Your tits look nice in that bra."

Nova's hand flew up instinctively to cover herself more, but she caught herself and dropped it back down. "This isn't even a sexy bra."

"It's working for me," I said.

"You know, if you're going to be too horny all the time, it's going to affect my ability to get any meaningful data," Nova said.

"Maybe it just means you're better at attracting attention than you thought," I suggested.

"Or maybe I've trained you that if you compliment me, you get handjobs," Nova said.

"It can be both," I said. "Speaking of which..."

"You want me to jerk you off?" Nova asked.

"Yes please!"

She made an exasperated noise. "Ok, well I want to anyway. I think I'm getting pretty good at it."

"You are," I confirmed.

"But can we at least get some quick research in first?" she asked.

"Probably," I said. "It usually goes well for me."

Nova nodded. "That's true. I'm going to need you to try and be objective though. I really do have sexier underwear. I'm going to try some options on, ok? And I need some actual answers about what is more attractive and enticing."

"Deal," I said. "That's a sacrifice I'm willing to make."

Nova rolled her eyes and opened her underwear drawer. "Don't look until I say, ok? And... if you want to take your things off..."

I was already slipping out of my shirt and boxers, leaving myself naked in my sister's bed. That was a bit of a weird feeling, but I was far more interested in Nova than in my own slightly out of place feelings.

I watched Nova slip out of her jeans. Her cute little butt looked really good just in panties. She slipped out of those too, and into what was admittedly a noticeably sexier pair. She did the same with her bra before turning around.

"Ok, what do you think?" she asked.

"Hot," I said.

She glanced at my cock, which was halfway to life already. "I know that's not a lie," she said. "But also not very specific."

"I'd say really hot," I said. "But I feel like there's something better coming, and I want to save some options."

"You're so very hopeless as a research assistant sometimes," Nova grumbled, turning around and unhooking her bra.

I could tell she was pleased though. She craved attention and compliments, even if ostensibly it was more about the data for her.

It took Nova a couple changes before she realized I wasn't closing or averting my eyes as she swapped bras and panties.

"Sol!"

"What?"

"I said don't look while I'm changing," Nova said firmly.

"Yeah," I said.

"You've been looking the whole time, haven't you?"

I nodded. "Most definitely. I like your butt."

Nova blushed softly. "Of course you do. Not the point. I'm... not ready for you to see me naked."

"It was only from behind," I said.

"Still!"

"Sorry," I said, smirking away any gravitas my apology may have held. "Come here though," I beckoned.

Nova folded her arms across her breasts. "Don't know that I want to."

"I want to see you closer," I said. "I think this is the best bra and panties combo yet."

Nova relented a bit and took a couple steps closer. "I think so too. It's hard to find something that accents my chest without, you know, making it look like I'm trying too hard."

"Well it's working," I said. "All I want to do is get that bra off you."

"Behave," she urged, padding closer still. "What about the panties?"

"Very hot from the front," I said. "And barely there in the back, which is perfect. Spin for me?"

Nova did a slow twirl. "I can't actually dare wear them anywhere," she said softly. "They really are barely there."

"But for purposes of wanting to get them off again anyway..." I said.

"Yeah," she said, daring to crawl into bed with me. "For those kinds of purposes." She bit her lip. "You really think I look good? You're not just trying to trick me into getting naked?"

"It can be both," I murmured, pulling Nova close and nipping at her shoulder.

"Ah! No fair," she whined.

"None of it's fair," I whispered. "The things you've been doing to me lately, you think that's fair? You see me being too horny for my sis-ter and think you're getting worse research. Just consider perhaps that what you're doing is getting your brother this obsessed with you. Maybe that means it's all going better than you hoped."

Nova was quiet a worryingly long time, as I tried to distract both of us with kisses to her neck and shoulder, not quite daring for a real kiss, or to bite her any more until she said something.

"You're obsessed with me?" she finally asked.

I hesitated. That hadn't really been my point, but I had indeed said it. "Um..."

"Are you though?" Nova pressed.

"How bad is it gonna be if I say yes?" I asked.

"It would... change things," Nova said.

I sighed. "Yeah, it would, huh? I'm sorry."

I lay back. Nova followed slowly and deliberately. We lay there together, me naked, her in her underwear. Sexy underwear, even. I was still horny, but had more pressing concerns now. Such poor timing.

"I don't think you need to be sorry," Nova said.

I shrugged. "Maybe not. It's confusing."

"It is," she agreed. "But you're right. This might be counted as a pretty big success for me."

"It might well," I said.

"Are you obsessed with me, Sol?" Nova asked softly.

"I think so, yes," I said.

Nova teased fingers up and down my chest. "I might like that," she said.

"Oh?"

"I might feel kind of the same," she admitted.

"For real?" I asked, suddenly hopeful.

Nova shrugged. "It feels good making you horny. Or getting you off. Or when you really badly want to play with me."

"I really badly want to," I said, voice cracking midway through.

"I know," she said, hint of a smirk returning as she grazed my erection with her fingers. "You're pretty hor-ny, bro."

"That's what you do to me," I told her.

I tried out a quick nip of Nova's shoulder. She hissed in pleasure and curled her fingers around my cock.

"You... do things to me too," she said.

"I know. I like getting you horny," I said.

"Kinda pervy, Sol," Nova teased. "Wanting to turn your sister on like that."

I didn't bother arguing who was the more pervy, if that was the criteria we were going by. She knew very well it was essentially a tie game between us at this point.

Instead of debating, I moved in to bite her neck and shoulder, feeling the delight as she squealed and squirmed, but kept offering her tender skin up for more. My sister's body was endlessly fascinating to me as I explored her with teeth and lips, and roaming hands over her sides and tummy and thighs.

"Solll!" she whined. "That's not fair!"

"You liiike it," I teased.

"Yeah, I do. But I'm gonna need... more."

"So tell me what you want," I offered, running my fingers dangerously close to her pussy.

"I can't," she gasped. "I'd need to... take my panties off for that."

"Unf, I'm into it," I said.

"I know," she giggled. "You should have felt your cock pulse when I said that."

"So what's the problem?" I asked.

"You'd... see it," she said.

"Ideally, yeah," I said.

"That's embarrassing!" Nova said.

"It's sexy," I said. "I want to see it. I want to... do things to it."

"With your fingers?" she asked. "Maybe you could close your eyes?"

I felt the thrill run through me as my mind caught up to my own words, and I realized that no, it was not my fingers I was referring to.

"Nov," I said more calmly than I felt, "I'm not going to close my eyes. And I'm not going to finger you. Not just that, anyway. Can I take your panties off?"

Her eyes widened. "Bad!"

"I know. Can I? Please?"

Nova squirmed. "How am I supposed to say no to you right now when you ask me like that?"

"So don't say no," I suggested lightly.

She looked at me, pleading. "What if you get bored of me once you know all my secrets?"

"Are you serious right now?" I asked. "You've always been a little weirdo, but boring? Not since I've ever known you." I ran my fingers up her thigh, over her tummy. "You got your own brother looking at you this way, and you worry about being boring?"

"Well..."

"Are you bored of me now that you've seen me naked?"

Nova shook her head. "Hell no."

"So?"

"You really want to see my pussy?" she asked.

"Really, really badly right now, yeah," I said. "And... I want to try licking it."

"Unf, ok," Nova agreed. "That sounds... really nice. I haven't felt that before."

"I might not be any good at it," I cautioned.

"Oh who cares about that," Nova said. "If we're bad at it, we'll just practice more."

A weird mix of pragmatic and paranoid, my sister. But then, I understood, I thought. We were taking this experimenting pretty far at this point. Probably too far. But we didn't want to stop. If only she saw herself the way I saw her and felt what I felt, she'd know the last thing she needed to worry about was boring me.

I was more entranced and devoted with every new way that I saw her, the more exposed the better. The way she felt under my touch, the way she made me feel when she played with me. She had so much more of a hold than she apparently realized. It was more than just the physical gratification, so much more, and was leaving me so much more connected to my sister than was probably wise.

"Nov," I said softly. "Can I please take your panties off and lick your pussy?"

She whimpered and clutched part of her sheet up over her face, only leaving her shining little eyes peeking out at me. "Ok. It's still no fair asking like that though."

"How did you want me to ask?"

"I don't know. Less sexy and intense, I guess."

"But then you might have hesitated longer," I said, hooking my fingers in the sides of my little sister's panties.

"I could have thought it through better," she said. "Made a rational decision based on evidence and predicted outcomes."

I pretended to consider her point. "Nah," I decided. "Better my way."

I tugged at Nova's panties, pulling them down fast enough not to let her weasel out, but slow enough to savour the full breadth of the experience. She was still being cute and shy covering most of her face, but she was watching ever so intently too.

Her pussy drew me as soon as it was uncovered, and I barely managed to remove her panties entirely before I was lying between my sister's legs.

I was afraid of Nova getting too shy if I stared for long. I wanted to examine her more closely, but I also wanted to taste her. It was crazy how strong the urge was to lick my baby sister's pussy.

"Ah! Ooh..."

I grinned as I got immediate response from Nova. She tasted good, and I would have kept going anyway, but reactions from her made it so much hotter.

"Do you... like it?" Nova asked.

"Mmhm," I moaned in between licks.

"I wasn't sure... when I started keeping it shaved... I think boys like that?"

"Overthinking again, Nov," I said. "But... yes, it's pretty."

She made a very cute noise and shut up for a while as I ate her out.

I could tell I was only hitting a surface level of pleasure for Nova at first. It wasn't like either of us really knew what we were doing. But we both enjoyed it, and together we slowly homed in on what made my sister feel particularly good.

"Ah, yesss, suck there," she pleaded when my lips closed loosely on her clit. "Suck it. Gently!"

I happily obliged. Sucking on her felt sexy and natural to me, and the way it made her react was super fucking hot. I loved Nova's obvious moaning and squirming as she got off. I even made her cum, which I hadn't been totally sure about. I was pretty proud of myself for that one.

"Oh fuck, Sol," Nova whispered after.

"Fun, right?" I said, kissing her thigh. "See what good happens when you let your brother see your pussy?"

She giggled softly. "You're going to be unmanageable, aren't you?"

"Most likely, yes."

Nova nodded contentedly. "Good."

I crawled back up next to her. Nova appeared happy and lazy, not hardly moving even when I fiddled with her bra and took it off. She barely even put up a pretense of being shy when I finally got to check out her bare tits for the first time. Maybe I'd gotten through to her by now that I was enamoured with her, and there was no need for her to be shy about much of anything.

The biggest surprise for me was that Nova hadn't yet grabbed her notebook. It was within her reach, but instead she just kind of lay there, relaxing and luxuriating. She grinned as I played with her tits, and perhaps even arched her back a little for me, but didn't jot down any frantic notes.

"Good boy," Nova purred, patting my head as I sucked on her nipples. "Good brother."

"You'll make me hard saying stuff like that," I said.

"You're already hard," she giggled. "You think I can't feel that poking me?"

"Hehe, true."

I gently guided my sister's hand to my cock. She gripped it instinctively, and I didn't have to prod her into stroking me. She just did it like it was the only reasonable course of action once my erection was wrapped in her fingers.

There was no urgency to any of Nova's movements. She seemed quite happy to let me play with her while she jerked me off in no particular hurry. It was only when I got close to cumming that she even started encouraging me in her usual way.

"That's a good brother," she murmured. "Cum for me. Cum for your sis-ter while you suck on her tits, ok? Be a good boy."

I whimpered and came in her hand and all over her tummy while she kept stroking and milking every little bit out of me. She made it feel so good. I was helpless against her sometimes.

We snuggled together afterward. I wasn't sure which of us needed it more by then, but there was no question of me leaving for my own room.

Nova finally got around to taking her notes while leaning cozily up against me.

"Would you say you like 'good brother' or 'good boy' better?" she asked. "You reacted nicely to both of them, I thought."

"I... they're both good," I said, not bothering to obfuscate.

"Thought so," she said. "Which is good, I think, because we don't want to overdo the incest thing. Gives more options, you know?"

"Right," I agreed, somehow straight-faced while cuddling with my baby sister and lazily circling the nipple of one of her breasts with my fingers. "Wouldn't want too much incest."

"Exactly," Nova chirped, deliberately not interacting with my sarcasm. "Gotta save it for a treat."

"It always is," I admitted.

She smiled and nodded, then frowned. "You don't think you'll start losing interest now though, right? Now that I've been fully naked?"

"Again with that?" I sighed. "Nov, I don't know that I can be anything other than helplessly fascinated with you while you're naked. Especially when you're playing with me. Or vice versa."

The cheeky little smirk she gave me led me to believe she'd been fishing for something like that from me rather than being genuinely worried. This new, growing confidence in her had the potential to be dangerous going forward, but in all the best ways, hopefully.

****

I couldn't help myself but want to go to bed with my sister every subsequent night. An empty, lonely room just felt wrong in comparison.

Nova made some noises about how it was hard to keep gathering data if we didn't give any time and space for feelings to arise naturally. I'd almost think she was getting annoyed about that, except one night when I was up late watching a movie, she impatiently came to my room instead, sneaking in wearing one my shirts I must have left behind some other night. She had nothing else on, as it happened.

"You were really taking your sweet time tonight," Nova complained.

"Sorry," I said. "I was busy. Besides, didn't you want to take some nights off here and there?"

"I said no such thing," Nova said, tugging my borrowed shirt up and exposing her cute, secret little pussy.

"You did too," I said, getting naked and crawling into bed with her. "You said we're getting worse data doing this every night."

"That's true," Nova said, sighing happily as my mouth closed on her sweet little cooch. "But that's a very different statement, albeit strongly related." She bit her lip. "Yes it would be nice to see how we both felt taking a few days or weeks off, for the research of it. But I don't see how we could realistically do that now. Mmm, now that I know how good this feels." She patted my hair. "You make me feel so good."

I beamed warmly. "Excellent. I don't want to stop now, even for the sake of your notes. Maybe especially for that."

"That's ok," my sister purred enigmatically. "I have some ideas on gathering more experimental data."

I was slightly worried about what that meant, and with good reason as it turned out. It was mere days later before we had an absolutely gorgeous weekend day, no particular plans, when Nova decided to invite Skye and Aurora over to lounge in the sun.

It could have had nothing to do with me. Skye and Aurora were Nova's best friends, after all, and it would be perfectly normal for them to hang out together. Given the abnormally sexy bikinis they all wore, however, I knew what this had to be about. I didn't think any of the three of them would have dared wear anything so skimpy if there were parental figures about.

I puzzled on the matter before venturing out. Mainly as to whether I thought Aurora was in on the game. Skye had been involved already, and was no doubt still very aware of the experiments going on. Aurora most likely had been briefed to some degree, but there was no way of knowing for sure without involving myself.

There was no question of staying indoors during this. Nova had done a spectacular job ensuring my interest. All three girls wore bikini tops that showed off and flattered their chests, and left their midriffs entirely exposed. Their bottoms left them only technically modest in the front, and were nearly swallowed up from behind.

They wore outfits, I concluded, that I had never known any of the three of them to be comfortable with under any other circumstances, and were almost certainly meant get some interesting reactions out of me. I decided firmly that this must be the case, and even so it still worked like a charm. There were times when I had to admit just how uncomplicated and predictable I could be. Nova was really making it clear lately.

I debated how exactly I wanted to join the three of them outside, and ended up opting to ditch my shirt, wearing only my shorts as I ventured into the bright, sunshiny day.

Skye and Aurora were immediately shy about my presence. Not averse to it, but definitely blushy and trying to cover themselves a bit, preserve some modesty that just wasn't there. It was a mark of how familiar Nova and I were with each other now that she was perfectly at ease letting my gaze sweep over her barely covered body.

"Nice day, huh?" Nova remarked casually.

"I'd say," I answered just as calmly, not hiding the way my eyes roamed across the three girls.

"We just decided to get some sun," Nova continued airily.

As though that was all this was.

"Good thinking," I said. "Me too."

I stretched out on a lounger next to Nova, pretending to ignore her and her friends. It wasn't easy, since I really badly wanted to keep staring. I was absolutely correct that they wouldn't be content to leave things like that, though, and it wasn't long before I detected the girls up to something, even with my eyes closed and ostensibly not paying them the slightest attention.

"Hey Sol?" Nova said.

"Hm?"

"I think we perhaps forgot to put sunscreen on," my sister cheerfully informed me.

I groaned softly at the immediate implications. "Did you?"

"Yeah," Skye added softly. "We did."

I glanced over, finding Skye and Aurora both looking flustered but excited. Nova was smirking so hard I was afraid she'd injure herself due to excessive smugness.

"Your pretenses are getting awfully flimsy," I told my sister.

"Tell me you don't want to help out," Nova taunted me. "I dare you."

She twirled her pen in her fingers, notebook poised on her lap, because of course she brought it out with her. Just waiting to jot down how easily I could be made to react the way she wanted. Which, to be fair, was pretty damn easily at times.

"Not very scientific of you to always be running experiments you know the results of," I told Nova.

She frowned. "Well... damn, that's a good point actually." She sighed and looked at her notes. "My methods might be getting less scientific at that." She brightened back up pretty quickly. "On the other hand, one might think that thanks to my previous investigations and experience, I can now use my gained knowledge to achieve predictable results."

"That's a lot of words just to say you're horny and have abandoned scientific rigour, sis," I said.

Nova stuck her tongue out at me. I did the same back to her, then deliberately passed her by to go rub sunscreen on Skye first.

Skye, rolling to her front, giggled nervously as my hands touched her shoulders, then ran down her back. She relaxed into my touch pretty soon, getting used to the feel of it, and even enjoying me cautiously straddling her. I'd been half-hard already, and was quickly getting more erect as I felt up so much of her bare flesh, only lightly impeded by her scandalous bikini.

Skye gave little gasps and mewls every now and then. I felt her muscles alternately tense and relax. I let my cock grind against her butt through my shorts, and my fingers roam all over her back and down the sides of her tits. Figuring out how she reacted to every specific thing was pretty fun.

I eventually made sure to cover Skye's legs and her butt. She tensed again as I reached under her skimpy bikini bottoms, but didn't stop me from feeling her up at any point.

Aurora was next. She'd been watching me with Skye the whole time and knew exactly what to expect. She was even more shy and tense to start with, but once she relaxed she stayed that way.

It was like having her body melt under my fingers as I rubbed her all over, from neck to feet. I was more cautious initially about grinding on her ass, or sneaking feels of her tits and booty, but the more I got away with, the less restrained I felt the need to be. I could just play and we'd both enjoy ourselves.

My sister was last up. She'd been observing and noting, but she all too eager to put the research away and lie down when I approached her.

"You're getting your shorts all full of sunscreen at this rate," Nova told me.

"I suppose I am," I agreed.

"Bit of a shame," she said.

I glanced at Skye and Aurora, knowing I didn't have to worry about what my sister would think, even if she hadn't already thickly hinted at it. I shrugged and pulled my shorts and underwear off, getting naked for the three girls. There were gasps and murmurs from Skye and Aurora, and nothing more than a silent, pleased smile from Nova as she made herself comfortable.

I wasn't about to be the only one naked. I liked the attention, and it did feel incredible to let my free erection rub directly on my baby sister's hot skin, but I still intended to make things more even.

Nova pretended not to even notice when I untied her bikini top while I massaged sunscreen into her. She couldn't ignore the removal of her bottoms quite so easily, and she gave me some cute little noises and wiggles as she was stripped nude. She even arched her back and stuck her butt out, inviting me to rub there as well. As if there was any chance in hell I was skipping over my sister's tight little bum.

I rubbed Nova down for much longer than necessary. Well past the point any argument could be made that she needed more sunscreen coverage. Much of that time was incidentally spent grinding on her ass as well. I was horny and softly panting, and mixed plenty of precum in with the sunscreen on her butt and lower back.

Eventually I thought she must have had enough and I was pushing my luck to go any further. I stood up, and almost immediately Nova rolled over.

"You missed my front," she informed me. She tried to keep her expression neutral, but her eyes were so gleaming and excited for me to keep rubbing her all over, in front of her friends no less.

This led to me covering absolutely every inch of Nova from the neck down, as well as carefully doing her face. There was something oddly intimate in the latter, though her naked body was the more obviously horny part of the experience.

Nova was absolutely soaked by the time I graced her with some attention to her pussy. I'd worked over everywhere else thoroughly before finally touching her there.

"He's really gonna," Aurora whispered.

"Yeah, just watch," Skye hissed back.

"She's his sister though," Aurora said.

"You knew this was coming," Skye giggled.

Aurora made a strangled little noise, but her eyes never left Nova and me.

"You know we can hear you, right?" Nova said lazily. She grinned at me as she spoke. She wasn't bothered. If anything, she was loving showing off like this.

It was so hot rubbing my sister's pussy in front of her friends. I got that. The added thrill of it. But at a base level I just loved making Nova feel good. I was feeling more and more comfortable with that part of myself. Like it was just part of who I was now.

I rubbed Nova so good, getting her all built up, then smirked and looked deep in her eyes.

"Cum for me, ok?" I said.

Her eyes widened. "Don't!"

I smirked wider. "Cum for you brother. Be a good little sister. Cum for your big brother."

"Dooonnn't," Nova whined. "Not this time."

"Yes this time," I insisted. "Your brother wants your cum, ok? Do it for me."

I kept murmuring to her, but she came pretty quickly once I got into our usual incestuous finisher. It would have been more intense for her, knowing both her best friends were watching what got her off. She came so hard for me, like a good sister.

I told her so, too. "Good sister," I praised. "Good girl. Very good."

"Stop," she mumbled. "I already came."

"Yeah you did."

Skye awkwardly cleared her throat next to us. "Um... I could be a good sister too, I think."

I blinked at her, slowly smiling again as I saw the horniness and need in her.

Nova, still in post-orgasm relaxation and bliss, laughed and gave me a push. "You heard her."

I tweaked my sister's nipple fondly in parting, and moved straight on to her friend.

Skye stiffened as I removed her bikini top and tugged down her bottoms, but didn't protest and even helped me out getting her naked. She needed assistance relaxing and feeling comfortable was all. Once I started playing with her and all that built up arousal had somewhere to go, she relaxed pretty well.

Since I hadn't slathered her front all over in sunscreen beforehand, I experimented with sucking on Skye's tits while I rubbed her pussy. I wasn't sure she'd want me to, but she happily moaned in encouragement.

She liked it even more when I sucked on her pussy, as I'd hoped she would. I really found myself enjoying eating pussy, and apparently that wasn't limited to only my sister.

I looked up at Skye when she got close to cumming, rubbing her with my fingers while my tongue was otherwise occupied.

"Be a good sister and cum for me," I told her, feeling like it would work under the circumstances. "Cum for your big brother."

I heard Nova snickering about it, but Skye did in fact cum for me as I finished her off with some more clit-sucking. I was quite pleased with myself, and Skye had a happy, contented face when I looked up at her.

"So the incest thing is looking like a good angle," Nova mused over the sound of her pen rapidly scratching across her notebook. "Not even just for you and me, Sol, as I had previously assumed. This is why doing the research is important."

I declined to ask what exact difference that knowledge made for her. It didn't really matter. To me, it was just hot and fun that I got to eat out another 'sister' just now.

"You're so scientifically minded," I told Nova, voice laden with sarcasm.

"I'm glad you understand that now," she replied without a hint of irony. "I was afraid you wouldn't."

"Oh I understand all about you," I said.

Nova paused. "That sounded vaguely insulting, somehow."

I beamed innocently. "Who, me? Never, I assure you."

She narrowed her eyes. "If you don't believe in the research..."

"No no, happy to help with that," I said.

I rose from Skye and padded slowly over to my sister, dick hard and swaying. I enjoyed the way her eyes widened and fixated on my erection as I approached. For a moment, I just let my cock stick out practically in Nova's face, but not quite close enough to touch, then I bent down and gave her a quick bite on the shoulder.

Nova made a cute, surprised noise and almost immediately clapped a hand over her own mouth as though embarrassed by it.

"But I do think sometimes we're just being horny and slutty, and science has very little to do with it," I said in a low, deliberate voice.

I wasn't sure what I expected from Nova, but the way her eyes lit up was not it.

"You think I'm slutty?" she asked.

"I mean... I said we," I said, confused. "But yeah, kinda."

Nova grinned and flipped her book to a different page. I didn't even want to ask what kind of information I'd just helpfully bestowed upon her.

I turned toward Aurora instead. She'd been very quiet, and was curled up in a shy ball on her lounger. She blushed as I looked right at her, but she didn't outright avoid eye contact.

"Do I... have to do the incest thing?" Aurora asked tentatively.

I perked up at the implication that she wanted some sexy fun, just not the kink part of it.

"Aw come on," Skye giggled. "It's fun." She looked up at me with some very cute eyes. "You made me feel so good, big brother."

Skye laughed as I groaned and very obviously produced some more precum from my twitching cock. The liquid drooled off the tip, making my feelings and state of horniness way too clear.

"Sol does enjoy that kind of thing," Nova agreed.

"Not just me," I said.

"No," Nova purred. "Not just you. But right now... mostly you."

"Are you taking notes about how I react to girls calling me big brother?" I asked my sister.

"Hehe, what do you think?" Nova said. "I thought you just liked it when it was me. But you like Skye saying it too. And... probably Aurora?"

Aurora was still blushing furiously, and held her arms tighter around her knees, but she took a deep breath and gave in.

"Please... big brother?" she said.

Nova and Skye cheered. I wasn't sure how much was for Aurora participating, and how much was for the way my cock twitched as she spoke those words.

I focused on Aurora to avoid the overstimulation of Nova and Skye joking back and forth and teasing me. She similarly did her best to ignore her friends.

Aurora took some work to get her to open up. She was shy about revealing herself, but very horny too. It made for a delicate but fun dance teasing her arms away from their protective lock and slipping her top off. The more I played with her chest and down her sides and tummy, the more she let her legs fall away too and allow me access her warm, needy body.

"This is gonna feel good, right?" Aurora asked.

"I think so," I told her. "You'd have to ask Nova or Skye though, they're the ones who've been on your end."

"Not right now I think," Aurora said. "Let's just try it."

"That's the spirit!" Nova praised. "It will feel good though. Definitely."

Aurora bit her lip, still not looking at her friends, and opened up her legs to me. Her bikini bottoms were enticingly wet, and though she still acted shy about it there was an eagerness in her as I removed them.

I sucked on Aurora's tits while rubbing her pussy until I felt she had properly melted for me, and was fully relaxed to my touch. I then moved downward so I could lick her pussy. She really liked that part, and the remainder of her inhibitions seemed to leave her.

"Oh that's nice," she whispered.

I happily sucked on Aurora's clit, making her whimper in even more pleasure. I heard Nova and Skye murmuring and giggling to each other, but kept them tuned out until I made Aurora cum.

I was pretty proud of myself after her. Three girls in a row letting me play with their pussies and cumming for me.

"Good boy," Nova said, sneaking up behind me while I was watching Aurora recover her senses. "Really being a good brother today," she added, running her finger up my spine.

"You're obsessive," I said.

Nova leaned right in next to my ear. "Oh? So you don't want to keep playing with your little sis-ters?"

"Novvv," I whined.

"Yeah you do," she said. "I know you do."

"You're getting dangerous," I said.

"That's one word for it," Nova said flippantly. "Knowledge is power. For instance... I know what you need now. And if you're a good boy, you'll get it."

She had her tits pressed up against my back, whispering sweet promises in my ear. There was a cynicism to the way my sister cajoled me, but it was very much rooted in us having a fun time together.

Succumbing to Nova meant her and her friends nakedly crowding around me, playing with me, running hands and mouths over me. It was hard to hold her manipulations against her when they worked out so wonderfully for me.

"Feels so weird," Aurora said, her fingers loosely wrapped around my cock. "So hard and... pulsing."

"Unf, nice," Skye said. "Let me try."

Nova had her fingers in my hair and her tits in my face. There was a slight sunscreeny taste to her nipple at first, but that faded and I just enjoyed sucking on them.

"See, you're getting taken care of too," Nova told me softly.

"Never doubted it," I mumbled. "Does it all have to be so... experimental though?"

"But it is experimental," Nova said. "Whether I write it down or not. None of us really have that much experience. This is valuable whether you want to admit it or not."

I nodded, holding her close, enjoying how it felt to put my hand on her back and press her into my body. "You make a good point," I said. "I... I like learning with you."

"I knew you would," Nova said. "Science doesn't have to be boring."

I moaned softly as Skye and Aurora took turns flicking their tongues over my cock and giggling to each other.

"It's definitely not always boring," I agreed.

"Let me know if it ever is boring," Nova said seriously. "Because we can fix it if so."

I had to process that one for a moment. "The science? Or y--"

"Yeah, the science, obviously," Nova said a little too quickly.

I didn't want to push that one too hard. Not right now at least. It was hard to fathom that my sister would be worried about me getting bored. Of all the things she might be, boring was not one of them.

If she did have those kinds of fears, it explained her friends' presences some more. I did fully believe that all three girls were interested in the experience. It would be very like Nova to achieve multiple goals at once. She could very well be giving them chances to play with me and trying to keep things novel and exciting at the same time.

Admittedly, it was working. I'd never experienced anything close to three naked girls all over me at the same time, let alone two of them sharing my cock and either rubbing it or taking turns daring to lick it. It was intense and wonderful, and something I'd be fantasizing about for a long time to come.

I made sure to keep lavishing attention on Nova; holding her, rubbing her, sucking her tits, nipping at her shoulder and neck. I was increasingly distracted, however, and I could only last so long before Skye and Aurora made me cum hard. It was much needed, and kind of shut me down in ecstasy overload.

Cum got everywhere. The girls squealed and laughed as it caught them on the face or hands. A lot of it landed back on me as well. I moaned and shook through it, feeling my cock spurt over and over, making an absolute mess.

Nova was grinning to herself and stroking my hair soothingly. That was the first thing I noticed when I was able to notice anything at all again. Then it was Skye and Aurora sitting up and comparing the errant streaks of cum on their faces. Aurora seemingly won, having caught a shot right across one eye somehow.

"Good boy," Nova praised me softly. "Good boy. Good brother."

I whimpered and nuzzled against her tits. Not horny just now, but happy for any comfort she could provide. I felt oddly delicate and exposed all of a sudden, though that faded away pretty quickly and I just felt lovely and relaxed.

I felt quite pampered once Skye and Aurora finished comparing cumshots and cleaned themselves and me up, followed by proper application of sunscreen to all exposed areas. Nova didn't go anywhere the whole time, ostensibly for my sake, but she also seemed quite content where she was. Enjoying the closeness as much as I was, if not more so.

"Shouldn't you be writing some things down about now," I asked her as her friends returned to their own seats but she stayed where she was.

"I'll get to it," Nova said without any sense of urgency.

I smiled and nudged her to stretch out with me, crowding our lounger, but making it very cozy with the two of us naked and lying out in the sun together.

She had thoughts about Skye and Aurora's reactions to my cumming on them. I knew she did. And about the way they'd played with the cum on me before wiping it up. I was actually kind of curious what sorts of things she'd write in her notebook. I wondered if she'd let me read it at some point.

But for now, I rated higher than her research, and that felt really nice. Perhaps I should insist on more naked sibling cuddles without her notes in easy reach. She might even go for it.

Things were changing. She couldn't pretend this was all just for research anymore. Not the way she snuggled with me and caressed me and occasionally whispered in dulcet tones. I rather enjoyed whatever it was happening between us, though I was hesitant to take that line of thought too far just yet.

****

All three of us stayed naked outside for a while. It was a funny thought when it eventually occurred to me how I didn't even stay horny the whole time. It was just a normal thing after a while. Nice for sure, and I enjoyed the view any time I looked about me, but not bringing up any particular urge to act.

Eventually, reluctantly, I decided I'd had enough sun and had to part with the wonderfully naked sister-cuddles. Nova pouted about it too, though acknowledged that she also would do well to head back inside soon.

I intended on a quick shower to rinse off any sunscreen before getting dressed again, but wasn't overly surprised to receive a visitor.

"Hey," Skye said, slipping into the shower with me. "Best to save water, right?"

She was a touch shy about it, but mostly showed a decisive boldness in the move. I wasn't about to kick her out in any case. Especially once her wet butt grazed my cock and stirred it back to life.

We helped each other wash off, though it was all just excuses to feel each other up. In particular me washing Skye's hair for her while her wet little booty was firmly pressed against me, trapping my cock between us.

I let my fingers drift downward, all the way down between Skye's legs where I rubbed her pussy while she gasped and let her ass grind back on my cock.

Nova and Aurora came into the bathroom as well, just about perfectly timed for Skye to cum on my fingers. Skye did her best to not make it obvious she was cumming, and Nova and Aurora were chatting away sufficiently that they might not have heard Skye's cute little cumming noises.

"You two having fun in there or what?" Nova teased. "Better have saved some hot water."

I helped Skye out of the shower, now that she was a touch wobbly on her legs. Nova gave me a smirk, then stepped past me into the shower, tugging Aurora along with her. The two of them weren't quite as sexual about it as Skye and I, but even just nakedly and platonically helping each other out under the cascading water was quite sensual and fun to watch.

After drying off, I took a seat on the floor facing the shower just to keep watching. Skye joined me, curling up with me and idly running her hand up and down my cock. Just casually jerking me off while we took in the scene of my baby sister in the shower with her friend.

It was all at least partly for my benefit. It wasn't like Nova regularly showered with her friends, even platonically. If this was more of her research, I couldn't really understand how much she could get out of it. Surely the fact that I enjoyed watching naked, wet, slippery girls helping each other wash themselves couldn't be much of a revelation.

"You're super into your sister, huh?" Skye whispered to me, still stroking my cock.

I blushed, knowing I was being pretty obvious about it. But then, it wasn't coming as news by this point.

"Yeah," I said.

"Good," Skye said. "That's as it should be."

"For... siblings?" I asked, confused.

"Not generally. But you two, yes," Skye said. She shrugged. "I wasn't sure about it at first, but I've come around."

"Oh," I said. "Good?" Her hand still felt amazing on me. "You weren't sure, but you still participated?"

"Yeah, of course," Skye said, grinning enigmatically. "The general premise of being able to try some stuff out in a low-pressure environment was tempting. And, you know, I didn't mind playing with you some. It would have been weird to date or anything though."

"Right," I said. I felt like the way things were currently was far weirder than just dating, but I sort of took her point.

"I did worry for Nova a bit though," Skye said. "She can overthink things sometimes and get herself in trouble."

"I don't know that overthinking is anyone's worry just now," I said.

Skye giggled softly. "That's only because you don't think like your sister. But then, hardly anyone does. That's part of why I love her."

I had to agree with that. Even if I didn't understand exactly what Skye was referring to, she was absolutely right in a general sense. No one thought quite like my sister, and that was indeed part of what endeared her to me and others. When it wasn't the source of exasperated frustration at any rate. Though for siblings, perhaps that was part of the basis for connection and love by default.

"Me?" Skye continued. "I would have been too jealous for something like today. Probably for sharing at all, actually. It wouldn't have occurred to me to consider the risks and rewards in the same way Nov would. Or to be willing to experiment with my own feelings on the line like that."

"Wait, what are you saying exactly?" I asked her.

Skye gave me a small, mysterious smirk. "Not my place to tell if you still need to ask."

"That's a nonsense answer. And kinda mean."

"Hehe, isn't it though." Skye rubbed her thumb over the head of my cock, sending pleasant thrills down my spine. "I think you'll be fine though."

Nova and Aurora stepped out of the shower, rather freezing my brain activity in place. Skye was probably right. Things were working out amazingly well for me, even if there was something I was missing. I should be used to that though, since when it came to my sister I was almost always a few steps behind. Not because she was smarter necessarily, though arguably she was, but just because of how easily she went off on wild mental paths that more or less made sense, but were nigh impossible to follow without a helping hand.

Skye amusedly jerked me off while I stared fixedly at Nova and Aurora drying off. Then, almost as a tease, the girls wrapped themselves in their towels, achieving a certain modestly if that word had any meaning between us at this point. Skye joined them too, leaving my poor cock untouched now that I was extremely horny all over again.

"We're gonna get dressed for a comfy movie night," Nova told me. "And get some snacks. If you want to join."

"I might hang out a while," I decided.

Still naked and prominently erect, my attempt at sounding casual probably didn't get me very far. It was worth a try anyway.

****

My cock actually had a chance to settle back down before movie night got going. I wandered about in pyjama pants and no shirt--a deliberate choice on my part--growing slightly impatient with the girls as they took their sweet time. The sound of occasional laughter coming from my sister's room made me wary of intruding. I had enough sibling self-preservation instincts not to intrude just now. It wasn't my place.

They eventually came out again, though dressed so casually I had to wonder what had taken so long. Just in long shirts, all three of them, and I caught just a flash of some sexy panties on Aurora that didn't cover much of her butt.

"Our hair was all wet and kind of a mess," was all Nova offered by way of explanation for the wait. "Had to sort it out."

"So not making secret schemes without me?" I inquired.

"We can do two things at once," Nova said airily.

"Of course you can," I said. "And... is that my shirt?"

Nova grinned.

"Wait, are those all my shirts?" I demanded.

"Thought you might enjoy it," Nova said, batting her eyes.

"When did you even steal those?" I asked.

She just winked and breezed away.

All four of us hit the kitchen to assemble snacks. We probably overdid it a bit, but we'd had a busy afternoon too, and were collectively hungry.

I kept finding myself staring wistfully at one girl or another. All three of them in my shirts, teasing me with possessiveness of some kind. The effect was all the stronger for the fact that I had so recently become intimately familiar with their naked bodies, and could easily conjure those memories again.

Nova caught me and my longing gazes more than once, and kept jotting it down in her notebook. It occurred to me that part of what had taken so long in her room might have been writing things down comparing and comparing notes with her friends. She'd been awfully restrained about it otherwise this afternoon.

"Yes, I'm enjoying you all wearing my shirts," I finally gave in and told her in response to her continued studies.

"Yeah," Nova said. "I know. I have eyes."

"Is it supposed to mean you're all claiming me, or vice versa?" I asked.

My dear sister leaned in to whisper to me. "No idea," she said. "But you liiike it anyway."

"... it's annoying that you're correct," I said.

I tried to pinch Nova's butt, but she skipped out of reach again.

We all settled in the living room once we had our snacks gathered up. We left the lights off, leaving things dim and cozy, mainly only the light from the tv illuminating things.

Nova placed me in the middle of the couch with her on one side, Skye on the other. Aurora tried to sit on the far side of Nova, but was nudged over to sit on my lap instead.

Aurora seemed a bit shy about her seat, but didn't mind it, even when having her in my lap got me hard again. She kept wiggling and softly giggling to herself as my cock hardened beneath her, and I had to lift her a bit a couple times to reposition. I ended up nestled between her butt cheeks, both of us occasionally grinding in small movements on the other.

Nova and Skye cuddled in pretty close on either side of me, but otherwise acted like it was a perfectly normal movie night. They snacked and made occasional jokes, and seemingly ignored Aurora and I being naughty in between them.

They did actually make sure I got offered some snacks or sips of a drink here and there, since I was pretty blocked off otherwise. I couldn't even really see much of the movie most of the time with Aurora in my lap. Which was fine, since playing with her was far more interesting anyway.

I really had the time and freedom to feel Aurora up however I wanted. Mostly I had my hands up under her shirt, to a point where Nova and Skye just started offering me bites of snacks straight to my mouth since my hands were busy.

Aurora got so horny as I felt her tits, teased her nipples, caressed her tummy, and kissed the back of her neck and her shoulders. I could feel her grinding back against me more and more insistently, though she wouldn't actually come right out and ask for me to go lower with my fingers. Possibly because it would be embarrassing for her to ask that with her friends right next to us.

I eventually ventured down to Aurora's panties, and immediately got a small but very satisfied sigh from her. She was soaking wet, and happily let me slide right into her panties to play with her pussy.

Aurora's little whimpers and the way she squirmed had to have been noticeable. Nova and Skye still acted like I wasn't fully fingering their friend right between them. Still just watching the movie and trading pithy comments.

Aurora eventually came on my lap. I was quite pleased with myself for getting her off, and very, very horny. She stayed where she was a bit longer, letting me hold her and cuddle her through her come down, then slid off of me.

As though rehearsed, Skye traded out places with Aurora and took over my lap as her throne. She rather cheekily tugged my pyjama pants down and off, leaving me fully naked with a prominent boner. I was happy to oblige her, since it meant more direct contact with my erection and her panty-clad booty when she sat down.

"Settle down you two," Nova said, still acting oblivious to the reason we might be causing disturbance.

I leaned over and gave my sister a nip on the shoulder as chastisement. She made a happy little moan and snuggled closer.

Aurora too was cuddled up pretty close on my other side, leaving my arms slightly pinned in. Being smothered by cute, horny girls was a really nice feeling as it turned out.

Getting to play with Skye was pretty fun. She was even more actively encouraging of my caresses, going so far as to move my hands where she wanted them and grinding very deliberately against my cock as a reward for making her feel good.

As I got Skye more and more turned on, she eventually lifted her butt up and slid my cock under her so she could grind her pussy on it instead. It was through her panties--her increasingly wet panties--but was still so very close to her bare pussy, and it felt incredible.

"Don't make him cum yet," Nova said.

Skye whined. "I knooowww, but it's so hard!"

"Restraint? Or Sol's cock?" Nova asked.

"Both," Skye said.

"You can... make me cum," I said. "If you want."

Nova bit my shoulder sharply. "No cummies! Not yet. Be a good brother, ok?"

"That makes it challenging, you know," I growled at my sister. "Skye's... getting me pretty excited here."

"Unf, am I?" Skye asked while forcefully rocking back and forth along my cock.

"You know you are," I said.

Nova was insistent I not cum though, so I took some control back by getting a hand down Skye's panties. Once I was rubbing her clit, she was a lot less needy about sliding her pussy all around on my cock.

I managed to get Skye off while maintaining my own composure, earning Nova's favour. The two of them switched places, Skye moving somewhat slower as she clambered off of me.

My sister was downright enthusiastic about taking a seat on my lap. Pretty horny by now, I realized. She'd had to wait through her friends getting to cum first and really wanted her turn.

It was even more than that, though. It took me a few seconds for my brain to process it, but as my sister pressed her tight little booty to my cock, there was no material at all between us.

"Nov?" I said in a strangled voice.

"Yeah?" she said.

"Are you not wearing panties?"

Nova shrugged. "Maybe not. Why?"

My cock nestled snugly in my baby sister's butt crack. Nothing between us. Just firmly wedged between her butt cheeks.

I couldn't say anything. I had no words. I pressed my lips to the back of her shoulder, just about where it met her neck, and tenderly bit her.

Nova gasped and couldn't help herself rocking against me, really grinding on my erection.

I slid my hands under her shirt, then gave up on subtlety and pulled it off her entirely. We were left both naked and grinding together, flanked tightly on either side by her slightly less horny and still somewhat clothed friends.

I wanted to cum pretty badly, but I wanted Nova to feel good too. I mimicked what I'd been doing with Skye and lifted my sister so I could trap my cock under her pussy instead of against her ass.

Nova whimpered and really focused herself on rocking back and forth, sliding her soaking wet pussy across my length over and over. I knew it was bad, but I couldn't help myself trying to move such that the head of my cock caught against her pussy just a little every time she was in the right spot for it.

"Sol," she panted. "You're gonna do a bad thing if you keep that up."

"I know," I told her.

"Unf. But then you'd be inside me," Nova pressed.

"Yeah, I know. You probably better make me cum," I said, kissing the back of her shoulders. "I'm getting... needy."

She pushed a little extra, nearly popping me inside her. I groaned in disappointment at nearly feeling it. This really was bad. I wanted to be in my sister. The urge was becoming overpowering. I wasn't used to it. But if she was going to let me get so horny and rub her pussy all over my cock like this...

"Sol?" Nova asked quietly.

"Yeah?"

"What if you were inside me though?"

I moaned and nipped at her the way she liked. "Don't tease me."

"I'm not," she said. "What if you were?"

"That would be... a lot," I said. "And it would be really nice. Unf. Damn, Nov, that would be amazing actually."

Nova stopped moving, with great reluctance, and slowly spun herself around in my lap to face me. She looked straight into my soul, the colours of the tv behind her providing an eerie sort of illumination.

"It would be... my first time doing... that," she said hesitantly.

"Yeah," I said. "Mine too."

"Is that ok, you think?" Nova asked, clearly looking for one specific answer.

"I think I'd really like that," I said. "I think that might be wonderful."

Nova nodded, giving a shy little smile. "Me too." She bit her lip. "Take me to bed?"

"Yeah," I said, trying to sound casual. "That's a good idea."

I tried to ignore Skye and Aurora grinning at us while Nova and I stood up. I had eyes only for my sister right now anyway. She looked so pleased and hopeful, and sinfully horny too. I felt like I must have appeared much the same.

Nova's hand slipped into mine, and we moved toward our bedrooms. It was a slow, cautious walk at first that quickly became a mad dash. I wasn't even sure whether we were headed for my bed or hers, but knew that we'd end up in one or the other within mere seconds.

It was hers, as it turned out. And even though I only had a fraction of a second to appreciate the sight of my eager little sister naked and bouncing into bed, needing me there with her so badly, that particular image was forever seared into my brain.

I was on top of her before she had any chance at all to plead for me to join her. We were both painfully, stupidly horny and needful of each other right now. Two excited, inexperienced, downright virgin siblings wanting so badly to share our first time together.

"Not how I thought this was gonna be," I admitted in a low voice.

"Me either," Nova said. "It was only supposed to be learning with you."

"It... still could be," I said, vocalizing one of the most difficult sentences of my life. "We could still stop now. We don't have to do this."

Nova looked at me with an expression that both made me shiver with arousal, and broke my heart a little.

"Don't make me beg," she said.

I grinned in relief. "Wouldn't dream of it. Just checking. You're... most definitely who I want."

"Good," she said. "Me too."

Skye and Aurora strolled in while I was positioning my cock against Nova's pussy. My sister got to have her friends with her, one on each side, holding her hands for emotional support while I sank into her for the first time.

My sister's pussy was a heavenly treasure, making me feel perfectly complete as it enveloped me. We both made some embarrassingly cute little noises as I filled her up. She was so wet and ready for me, easy to enter, but so tight, warm, and welcoming too. Like I was existentially home for the first time ever.

"Oh fuck yesss," Nova hissed softly. "More, ok? Do it."

"Novaaa," I moaned. "Why do you feel so good?"

"It's amazing," she said. "Keep going."

"Of course," I said.

I buried my face against her neck, letting my hips do their thing. In and out of my sister's precious little pussy. The absolute most perfect feeling in the world.

"I... do need to cum pretty bad," I said.

"I know," Nova said tenderly. "I know, Sol. I wasn't sure if I wanted this to happen, and whether I wanted it to last a long time or a short time." She made a happy, purring noise. "I realize now how silly that was. Just... do what feels good, ok? Don't think about it too much."

"Ha, ridiculous advice coming from you of all people," I said.

"Isn't it?" Nova giggled. "But for real." She nipped at my ear. "Just enjoy it. I am."

"Mmm, me too," I assured her. "So fucking good."

"Mmhm. Keep fucking me, ok Sol? Like a good big bro-ther?"

I giggled as I kept thrusting into her. "Don't do that! I really will cum too fast."

"Cum when you want to," Nova teased. "Just as long as you do. Cum for your sis-ter."

"Stop!" I laughed.

I shut her up at least temporarily by biting at her shoulder and neck, making her gasp and writhe beneath me. Her cute mewling drove me even crazier though, and I lost myself to the moment.

I exploded inside Nova. Inside my recently virgin little sister. My cum seemed endless and brought new satisfaction and relief with every shot. I felt so utterly transcendent and at peace as I filled Nova's pussy with brotherly cum. Like it was the most perfect and natural thing in the world.

Nova retrieved her hands from her friends and rubbed my back, holding me close and teasing her nails up and down my spine.

"Good brother," she cooed. "Good boy. So good."

"I came in you," I told her.

"Hehe, I know," she said. "Trust me, I know."

"That was... that was so amazing," I said. "So perfect."

"It was," Nova agreed. "Better than anything I hoped for."

I felt two bodies leave the bed. Skye and Aurora giving us privacy, perhaps. Nova and I stayed right where we were, hardly moving other than to breathe, and the loving sensation of her fingers up and down my back.

It was a while before either of us spoke again. I didn't have anything to add to the moment. Nothing that could make it any more perfect than it already was.

"I really didn't intend this," Nova finally said.

"You don't regret it, do you?" I asked.

"Not on your life," she said firmly. "Just... I didn't set out to seduce you like this. I want you to know that."

"I'm glad it happened either way," I said.

"Same," Nova said. "I think it's better this way too."

"Better than what?"

She shrugged. "I wanted to learn. Maybe get some experience. So I wouldn't feel so lost finding a boyfriend or having sex and stuff. It's kinda scary in some ways."

"I get that," I said.

"You were great. Too great, actually," she laughed softly. "The perfect boy to try stuff out with. And then... it got to be more than just experimentation."

"Kinda did, huh?" I said bemusedly. "I'm glad though, because I think if you didn't want more than experimentation it would have been difficult for me."

"Oh?" Nova said.

"Yeah. I think I would have struggled," I said. "I don't exactly what I would have felt, but I think it wouldn't have been good sooner or later."

"Sorry," she said.

"Don't be," I said.

"No, I am though," Nova said. "I didn't think about that. That I could actually hurt you. I see it now. I just thought it would be fun and educational. I forgot brothers have real feelings too."

I knew she was half-teasing, but she was definitely sincere enough too. I nipped at her bottom lip, just testing.

"Hey, Nov? Would it be ok if..."

"Hm?"

".. if I kissed you?"

My sister's eyes widened. "Oh yeah! Oh, we haven't done that, huh?"

"Not so much," I said. "Funny how we skipped that one."

"Well, you know, it was just science, a lot of it. Kissing kind of makes it real."

"Nov, you've got a pussy full of my cum. If it's not real yet--"

"Hehe, no, it's real," she said. "You know what I mean though." Her fingers were tender on my cheek. "It wasn't something I was going to do before I realized that I want it to be real." She sighed. "Really putting a damper on me finding a boyfriend though."

"Maybe a brother is better?" I suggested.

"Yeah, maybe it is," Nova said. "You gonna kiss me or what?"

I grinned and went for it. As ridiculous as it was to be naked and post-coital and still feel such electric nerves about a simple kiss, that was exactly what I felt. Kissing my sister. Releasing emotion more subtly but just as impactfully as cumming in her not long before.

"Your lips are soft," I told her.

Nova had the grace to blush and turn her head slightly away. "Shut up."

"Let me try again," I said.

"Are you going to say another weird thing after?" she asked.

"Well, you know, you need some stuff for that notebook of yours, don't you?" I said.

"You think like I don't have hours of notes to try and remember as is?" Nova snorted.

"Well a few more won't hurt anything then," I said.

I tilted her unresisting head back to me so I could kiss her again. It was just as wonderful the second time, and significantly less intimidating, which was nice. By the third kiss everything about it felt smooth and natural.

"I love you, you know," I told Nova.

"Well that's really gonna throw off my data," she said.

"Shut uppp!" I said.

"Kidding! Kidding." Nova bit my lip affectionately. "I love you too. Of course I do. More than usual, even."

We were still exchanging kisses and soft murmurs when Skye and Aurora returned.

"Haven't moved, huh?" Skye said.

"Told ya," Aurora said. "This is just gonna be weird now, isn't it?"

"Weird? Nah," Skye said, hopping back onto her edge of the bed. "Well, kinda weird I guess. But fun."

She emphasized her point by slipping her panties off and masturbating next to Nova and me, still wearing my shirt as she did so.

Aurora was slower to join in, but essentially did the same thing, except for leaving her panties on.

"Well that's gonna make me horny again," I said.

Nova traced my neck with her fingers. "I never stopped being horny."

"Ah. Well then... wanna, like, do it again?"

"Sex?" she asked, eyes gleaming.

"Yeah, sex," I said, matching her mischievous glint.

"I could go for some more," Nova said.

We'd hardly moved, so slipping back inside her took a minimum of effort. Nova made a happy little sigh and clutched at my butt, even digging her fingernails in, urging me deep into her messy pussy.

"I'm gonna get an incest kink at this rate," Skye muttered. "All this time thinking all that step-sister porn online was just silly."

"There's something to it though, isn't there?" Aurora said, finally giving in and removing her panties as well.

"Hehe, we're way ahead of you both," Nova said. "It is pretty hot, actually. Right, big brother?"

I dipped my head and gently closed my teeth on my sister's nipple. She gasped loudly.

"I know you're just trying to distract me," Nova said. "But... do that again. A little harder."

"Fuck me that's hot," Skye hissed, eyes wide and intent on us.

Aurora, at a more basic and feral level of arousal, moaned and whimpered her way through what I was pretty sure was an orgasm, agreeing with Skye's assessment in her own way.

I made my sister cum too with loving thrusts inside her, some tactical nipple biting, and the occasional carefully selected words whispered sensually to her.

"I love you," I told her.

"Mmm, I know," she purred.

"I want you to cum for me," I said.

"Unf. Ok," Nova said.

"Cum for your brother, ok? Like a good little sister. Such a good sis-ter."

She was so close and whining, and nipping at her nipples again sent her over, cumming on my cock and mewling into my shoulder.

"Absolutely ridiculous, the both of you," Skye panted. Though she came pretty quickly after that too, so I wasn't sure it was actually a chastisement of any kind.

"I'm a good sister," Nova said. "I came for you."

"Yeah you did," I agreed.

"You know what I need now?" she asked.

"My cum?" I suggested.

"Yesss," Nova said. "My brother's cum in me. Again. Even more of it. You want your baby sis-ter to be happy, don't you? Like a good big bro-ther?"

I was done for when she started talking like that and she knew it. I couldn't resist her saying those things any more than she could resist them from me. I came in Nova's accommodating little pussy for the second time in a row, and indeed the second time ever. She cooed and petted me like I'd done a really great job, rather than merely surrendering to the sexy inevitable.

Nova and I cuddled for a while, then all four of us headed back out of the bedroom to rehydrate and laze around some more. Nova and I stayed naked, and Skye joined in at some point after some joking around about her 'modesty.' Aurora kept my shirt on, but didn't replace her underwear.

We put another movie on, not that anyone was particularly invested in it. I spent most of my time cuddled with one of the girls or another, sometimes more than one of them at once.

Nova would frequently break away with Skye or Aurora to have some sneaky chats. I didn't try to listen in mostly, though I did catch Skye sticking her fingers up Nova's vagina at one point at was particularly interested in what that was about.

"Just... seeing what it feels like," Nova told me when she caught me looking. She grinned at my expression.

"That's gotta feel weird," Skye said. "Feels like a lot in there."

"It's weird," Nova confirmed. "But nice. Really nice. And sexy. And a reminder of like... stuff."

"Sex with your brother?" Skye teased, finally sliding her fingers back out and examining the cum clinging to them.

"Yeah, that," Nova said.

To my mild surprise, Aurora slipped out of my loose embrace and padded over to have a feel up my sister as well. Skye traded with her and snuggled up nakedly with me, still toying with my cum on her fingers.

"Are you... gonna leave all that in there?" Aurora asked Nova, finger-deep in her cooch.

Nova looked straight at me, devilish gleam in her eye. "Of course I am."

"It's kind of risky, isn't it?" Aurora asked, finally pulling her fingers back out. "All that cum?"

"If Sol knocked me up, it's kinda late to worry about it now," Nova shrugged.

I rolled my eyes and off-handedly tossed a cushion at my sister. "You're too clever for that to have been a risk."

"Well yeah, duh," Nova giggled. "But you could have at least gotten panicked for a second there." She fluttered her eyelashes. "Or maybe enjoyed the idea of breeding your baby sis."

I shook my head, but Skye betrayed me.

"His cock twitched a little just then," Skye laughed.

"Goddammit," I growled.

Nova sweetly kissed my cheek. "Knew it," she gloated.

"You did not," I said.

"Well... I know it now," Nova said.

She retrieved her notebook and assumed her place of honour next to me, with my arm around her and my hand on her warm tummy. She spent a while jotting things down--longer even than usual for her, though I supposed there was a lot to cover in this instance.

"Do I get to read any notes this time?" I asked.

"Absolutely not," Nova replied promptly. "They aren't for you."

Rather unfairly, she did let her friends peek at her writing a few times, and she collaborated with them on a few occasions as far as matching or clarifying some of the experiences of the day. Nova was just a bit smug about being the only one to know what it felt like having me inside her and getting cummed in though.

"What do you even need to record at this point?" I asked Nova. "I feel like you've got me pretty well figured out already."

"Because we had sex?" Nova asked.

"Mostly, yeah," I said.

"Do you feel like you have me all figured out now?"

I hesitated. "Not really, no."

"There you go then."

Our eventual bedtime was, unsurprisingly, a cramped affair as all four of us crowded into Nova's bed. Nova cuddled tightly up to me, of course, and Skye and Aurora found room beside us. No one mentioned it being an odd way to sleep, though there was a fair amount of shifting and grumbling as we all tried to get comfortable.

I didn't think I'd be in the business of getting any sleep that night, and I didn't even mind that much. I was sensually cozy to a degree I hadn't ever known before very, very recently in my life. Too warm, perhaps, with four bodies sharing the bed, but also soft and comforting being enveloped by nude or mostly-naked girls from all sides.

I must have fallen asleep at some point, despite my skepticism. The next thing I knew, I was gently being disturbed awake again. I flickered my eyes open just in time to watch Nova sliding my cock into her pussy while she straddled me.

"Unf, Nov, goddamn," I whispered.

"Sorry," she said. "I woke up and... couldn't sleep."

"So nothing to do with you being curious what it was like riding me while I'm asleep?"

Nova shrugged. "Maybe a little bit about that."

She rocked her hips ever so gently, but still enough to coerce a soft moan from me. She felt absolutely wonderful around my cock once again.

Aurora, having joined the rest of us in pure nudity at some point, probably because of how warm it was, stirred slightly. She was rather cutely clutching one of my arms, and in fact had snugged between her tits.

"Don't you two ever stop?" she murmured. "I was sleeping."

"So was I," I said. "Nov can't resist me though. What can ya do?"

Aurora nodded gently. "She's very horny. And she likes you."

"Yes," I said, watching my sister undulating atop me. "I think I might like her too."

Nova remained unperturbed. "Say it right. Tell me you love me."

I thought about teasing her, but her pace subtly quickened and I found myself wanting to please her.

"I love you, Nov."

"Mmm, good," she hissed.

"You're an amazing sister," I said as she rode my cock in the middle of the night right beside her slumbering friends. "I love you so much."

Nova nodded, reaching down to rub her clit while rocking on my cock. "More. Please?"

"You're the best baby sis-ter I could have ever hoped for," I said. "Actually, more than I ever would have hoped. I would never have dreamed of this, but I love it, and I love you."

Nova whimpered adorably.

"We're going to have so much sex," I said. "I want to make you cum as often as you need. You want to cum all the time for your big bro-ther, right? Like a good little sister?"

She panted, rubbing herself frantically. "Yesss."

Nova made herself cum on my dick with my frequent and naughty assistance. She rather considerately made sure that I came inside her again too before lying down atop me and going back to sleep. Once again drained, I pretty quickly returned to sleep as well.

****

The next morning was an incredibly lazy affair. We were all slow to stir and rise. I rather helplessly was the last to ever get out of bed, since even though the girls sleepily padded off to the bathroom and back, or to grab some water bottles, or whatever else, there was always at least one of them clinging to me, or atop me, or otherwise preventing me from going anywhere.

It was the absolute cuddliest and most wonderful captivity of all time, but my poor body could only take so much.

"You have to let me up soon or I'm going to piss the bed," I finally warned.

Aurora, currently most in the danger zone for such a threat, made a cute, alarmed noise and darted back away from me. Nova treated the threat less seriously, but on her own could be easily wrestled onto her back so that I could hop away and make my escape to the bathroom.

My dash for freedom got everyone up and about at last. We were all hungry enough by then for it to win out over continued sloth. At least sort of.

Breakfast was mixed preferences for toast or cereal. The very easiest options.

The dress code remained incredibly lax throughout. I put my pyjama pants on again, certain they wouldn't last long and that there was no point at all in dressing up any more than that. Nova wore yet another of my shirts and very obviously no panties underneath. She played a game of flashing her pussy or bum at me at almost every chance she had, delighting in her own lack of subtlety.

Skye was a bit less provocative than my sister this morning, albeit not by much. She'd donned her own shirt and panties, which was a pretty cute and sexy look too, if not quite as slutty as Nova's.

Aurora opted for actual modesty, dressing herself properly again in her own shirt and shorts. It was a tight and revealing outfit, but one that was very presentable in public.

We all hung out for a while in our various states of dress or undress. It was nice just to chill and goof around without it being particularly sexual. Though I wasn't at all bothered or surprised when the girls huddled up to whisper and giggle to each other, followed by Skye dropping to her knees in front of me and pulling out my cock.

"Probably gotta get going soon," Skye said, already running her fingers over my soft but twitching penis. "But... one more before then?"

I nodded assent, and Skye engulfed me, getting me hard with her mouth. She seemed to enjoy toying with me like that and feeling me get bigger on her lips and tongue.

I had just settled in for a casual blowjob in front of two amused witnesses--the sort of thing my life now entailed--when Aurora approached as well.

"Big brother?" she said, making me groan softly. Aurora still seemed shyer than Nova and Skye, but I felt like the gap had closed at least in certain specific ways. "Would you maybe eat my pussy for me?"

"Yeah," I said. "I might do that."

"Thanks, bro," Aurora said, already pulling her shorts back off again.

I glanced at Nova. "You're a very bad influence, you know."

Nova batted her eyes at me. "But you like it though."

"I didn't say I didn't," I said.

"You'd be lying if you did," Skye grinned. "I can feel what your cock does every time Aurora calls you her brother and asks you for something naughty."

Aurora, now bottomless, nodded eagerly. "I've been a good sister. I need my pussy licked." She said the words fairly confidently, though also blushed profusely.

Skye laughed. "Yeah, lick your sis-ter out, would you? We have been good girls, you know."

"I don't see how you have so much time to talk when your mouth should be full," I told Skye.

Her eyes flashed in amusement and horniness, and she stuffed her mouth full of my cock again.

After some negotiating of logistics, I ended up lying on the floor with Skye between my legs still sucking on me, and Aurora sitting primly on my face so I could lick out her sweet little pussy. I caught Nova lightly playing with herself while watching, though once Aurora had settled on my tongue I couldn't see much else.

My focus was all over the place, between trying to lick Aurora nicely and Skye's constant distraction on my dick. All the while part of my brain wondering what Nova thought about the situation. I didn't actually think my sister had put them up to this. I was pretty sure Skye and Aurora really just wanted a last bit of fun before they left.

I made sure to give them what they wanted as best I could. I knew my tongue-work wasn't at its best, from the angle and constant distraction of Skye's mouth, but I still made Aurora cum. Me cumming for Skye was far more inevitable. Both girls had cheeky, self-satisfied smiles afterward.

After dressing, Skye and Aurora said their farewells, which included some big hugs for me, and even a kiss on the cheek from Aurora.

"Thanks for... all that," Aurora whispered. "I get why Nov likes having you as a big brother."

"Come on, Aurora," Skye said, tugging at her friend. "I'll drive you home." She winked at me. "We'll come back and play sometime though, yeah?"

I sighed happily. "Hope so. That was fun this weekend."

Skye glanced at my cock. "Yeah it was. I've got some other ideas for next time too."

Aurora laughed. "Stop being horny. You've got to drive me home, remember? My parents'll be annoyed if I miss church."

"Yeah yeah, we're going," Skye said.

I blinked as I watched them hit Skye's car and pull out of the driveway.

"There's something mildly incongruent about Aurora concerning herself with church after... you know, everything," I said.

"Bet you like that," Nova teased. "Corrupting the poor innocent church-girl."

"That's on you, not me," I said. "But also... yeah, a little."

"Hehe, predictable."

Nova maneuvered me to the back deck where we could sit on the patio swing together, cuddled up in almost cute and platonic sibling manner, if not for my nudity and her lewdly splayed legs showing off her lack of panties.

We just cuddled though. Nothing sexual for the time being. It was nice.

"It's actually really nice that Aurora had a chance to open up like that," Nova remarked, opening up her notebook and staring thoughtfully at it. "She hasn't had much chance to date or anything."

I gazed curiously at my sister. "I don't remember you dating much either."

"Well no, but for different reasons," Nova said. "Not overprotective parents in my case."

"Certainly not," I agreed. Our mom and dad were pretty good about letting us make our own decisions. Not that they'd necessarily be thrilled knowing about what we'd been up to recently. "So out of curiousity, Aurora's parents must have thought it was just the three of you having a sleepover?"

Nova smirked. "Actually... they were happy to know you'd be around. To keep any sneaky boys away."

I shook my head and slipped my hand under Nova's shirt, letting it rest on her tummy just under her breasts.

"You like that, don't you?" I said.

"What, that my friends' parents think you're a good and safe boy, when actually you've been devious and sinful?" Nova chirped. "Yeah, might be some fun in that."

"Were you going to tell me about that part?" I asked.

"If it seemed amusing, sure," Nova said.

"You're something else," I told her.

"Thanks, probably." Nova shifted a bit and rested her head against me, then jotted a few quick notes for herself.

"I'm glad all three of you had fun this weekend," I said. "That I can be someone both safe and devious enough."

"Hehe, yeah. And I bet that's so very altruistic of you, huh?" Nova teased.

"It's at least a little altruistic," I pouted. "And only mostly self-serving."

"'Cause you liiike having three horny girls all over you," Nova said.

"Well... yeah." I kissed the top of her head. "Don't tell them, but you're my favourite."

"Well yeah," Nova giggled. "I put out."

"Oh my god. I mean... yes. But not really because of that. Although... fuck, Nov. That was incredible, wasn't it?"

"Mmm," she purred. "I was very happy about having sex with you. And I'm glad I did it with Skye and Aurora around. It was... intimidating. I know it doesn't need to be, especially now that I've experienced exactly what it feels like, but it was."

"I get it," I said. "It held... emotional weight."

"Ooh, yeah, good point," Nova said, scribbling rapidly. "That's a very good way to put it. I'll have to remember that for..."

"For what?" I asked.

"Well... if Skye or Aurora decide maybe they want to try sex too," Nova said. "I think they might."

"Unf. You'd just let them?" I asked. "With me?"

"Well yeah, probably," Nova said. "I don't think you'd mind."

"That wasn't my concern," I said. "Because you're right, I wouldn't." I teased her breast a little with my fingers. "I just feel like at some point you'd have to get jealous. I just don't know where the line is. Or even if there is one."

"Jealous?" Nova asked.

"Yeah, you know. Like if you share me too much with your friends, that like what if I stopped wanting you as much. Or something like that."

Nova went still and quiet.

I panicked a little. "Um... not that you need to worry about--"

"Shh!" Nova said.

"But--"

"I need to think for a second!"

It would be rather embarrassing of me to fuck up like this, I reflected while staying silent. After everything, to get caught up on the threat that I'd leave Nova for one of her friends. Which I absolutely wouldn't. I hoped she knew that. I was only marveling at her lack of jealousy.

But I didn't really think that Nova was incapable of jealousy. Only that she might not have felt it needed until I brought it up.

Nova finally stirred, flipping calmly to a new page of her notebook and writing slowly and carefully.

"I didn't think of that," she said in a low voice.

"Well like I was trying to say, it's not something that would happen," I said, hoping to salvage this still.

"No, I know," Nova said. "Probably why it didn't occur to me. But like... it should have. I spent so much time obsessing over making sure you'd be interested and stay interested, I didn't consider that I might actually lose you to someone else."

"I--"

"It was negligent on my part," Nova said. "I see how some of these experiments have been dangerous for me." She perked up a little. "The good news being that disaster did not in fact strike. I've seen you with Skye and Aurora. Very intimately in fact. And I don't need to worry."

I breathed a sigh of relief. "You don't," I assured her. "They're fun and I'm glad we could all enjoy ourselves, but they're not you."

"Because you love me," Nova said, making it halfway between a firm statement and a leading question.

"I love you," I said with no hesitation. "And this thing you said about making sure I stayed interested? Nov, you don't have to do anything crazy. We don't need fourways with your friends."

"Although?" she prompted.

"Although I'd like to have them around again," I admitted. "And... you're very good to me and probably the best sister ever."

"Correct," she said, snuggling even more cozily up to me. "You're a good brother. I'll probably even let you have sex with me again."

"Let me?" I asked, pinching her nipple sharply.

Nova gasped, then laughed. "Ok, ok. I want it more. Lots more. Ok?'

"Yeah, Nov. Very ok. I'd have to be heartbroken otherwise."

She tried to give me a teasing smile, but it ended up coming out fully genuine. "Heartbroken, huh?"

"Sad and horny at the very least," I said.

Nova giggled. "You would be, too. I liked heartbroken better though. Stick with that."

"Not very scientific of you trying to force the results," I pointed out.

"Technically true," Nova said, closing her notebook and closing her eyes while she leaned on me. "But I think there's a chance--just a chance mind you--that I've become too personally invested for this to be any kind of objective experimentation anymore anyway."

"Ha, ya think?" I snorted. "You couldn't be any more personally invested."

Nova chuckled softly. "You're right. And yet... I still want to keep going. I still want to learn."

"Yeah, I do too," I said. "I think that's normal to want to learn what you like. Even beyond the alleged scientific research of it all."

"Alleged?" Nova demanded, sounding perturbed.

"You heard me," I grinned.

She bit me rather sharply on the shoulder, making me gasp.

"This is all valuable, thank you very much," Nova said, tapping her notebook.

"Uh huh."

"You're lucky I'm so dedicated, really," she insisted.

"I am lucky," I agreed, implicitly declining the latter half of her statement.

Nova tried to sulk a bit and focus on her notes, opening them up to some further additions while we cuddled in the sun. I was as much distraction as I could possibly be, roaming with my hand or occasionally my lips. Nova laughed despite herself, and kept squirming to try and prevent me from caressing a sensitive spot, but she had lots to choose from.

When I started nibbling at her neck, she was done for, and finally had to give up on pretending to take notes.

"You're so needy sometimes," Nova chided, climbing nimbly into my lap.

"Is that what I am?" I asked.

She wrapped her arms loosely behind my neck, gazing intently at me. "Yes. You can't leave me alone."

"Nov, you're sitting there mostly naked and pressed sluttily up against me. If you wanted any peace, that was not the way to get it."

"Sluttily? Me?" she said.

I ran my hands under her shirt, up her warm flanks to her breasts, and then down to her tantalizing bare ass.

"Just a touch, yeah," I said.

Nova wasn't shy about grabbing my cock and making sure it was hard and ready for her. "Guess if I'm slutty this morning... there's only one thing for it."

"A cold shower?" I hazarded.

"No."

"Asking Aurora about joining that church of hers?"

"No!"

"Trying to--"

Nova put a finger to my lips. "Think very carefully about this next oh-so-hilarious suggestion of yours."

"... sex?" I offered carefully. "Sex for you with your bro-ther?"

Nova sighed contentedly and lowered her pussy onto my hard cock. "Much better."

"You know that's all I'm going to want anymore," I told her.

"Yeah," she said, biting my lip and rocking her hips. "I figured. Lucky for you, I might want to experiment with trying to get you to cum in me every day now."

"Just the once?"

Nova made a horny noise in her throat and rode me harder. "At least once. Let's say that."

I nodded. "Agreed. I can make that sacrifice. For science."

"How noble."

"That's me."

I removed my sister's shirt, hardly slowing her rhythm at all. I enjoyed having full access to her nude body outside in the warm, sensuous sun. I felt her up and kissed her, everywhere from her lips down to her tits. When I wanted to get her hornier and riding me faster, I started sprinkling in little bites here and there, just to rev her up.

"Fuck, Sol, you know what that does to me," she panted.

"I do," I confirmed.

"You're gonna make me cummm!"

"That's what I want," I told my sweet, sexually charged baby sister while she rode my cock needily. "I want you to cum for me. Like a good girl. Like a very good little sis-ter."

"I want you to cum in me," she panted.

"Mmm, that too," I said. "You cum for me, then I'll cum in you and you'll have to walk around with your brother's cum in you all day, ok?"

Nova giggled softly and whimpered her assent. I rubbed her clit and bit her neck while she whined at an increasingly desperate pitch before cumming on my cock just the way I wanted her to.

Thus sated, at least in part, Nova took back some control. She got the motion of her hips under more control, looked at me with narrow, wickedly gleaming eyes, and gave me the kind of smirk that could make me melt into her.

"Your turn," she said huskily.

I nodded. "Yeah."

"'Cause I need you to cum in me," Nova continued conversationally. "You promised."

I groaned softly. "I will."

"I know. Because you're a good big brother, aren't you?" Nova purred. "You're going to be a good boy and cum in your sis-ter's pussy." She laughed gently. "Well, maybe that's kind of bad of you, actually. You're a bad boy sometimes. But... still a very good brother."

"Novvv..."

She stroked my hair and nibbled on my ear. "You like that, don't you? You want to cum in me. In your little sister's pussy that's just waiting for it."

"I dooo," I said.

"Do it," she urged. "Good boy. Like that. Yesss."

I held Nova tight, clutched at her really, and came so deep in her pussy, filling her the way she wanted. She mewled and nipped at my shoulder, then went back to purring and stroking my hair and calling me variations of a good boy.

We held each other after, naked and sweaty and so very satisfied out in the sunlight of the back yard.

"I love you," I said.

"Love you," Nova echoed easily.

She hummed happily to herself and didn't get off my lap until my softened cock finally slipped out of her. Even then, she took her sweet time about it.

"So... we both really like when you cum in me," Nova said, flipping her notebook open and nestling comfortably against me again.

"You really need to make note of that?" I laughed.

"It's relevant," she said.

"I think we'll remember," I said.

"Probably," Nova said. "But I'm going to write it down anyway."

"I know," I said.

"And I really liked doing it outside like this," she added.

"Mmm."

"There's lots of places we can try," she said. "You know, just to experiment."

"How very scientific of you," I said, mind already considering possibilities.

"Thank you," she said. "Now... how long before you think you can go again?"

I laughed and hugged Nova to me, tickling her a bit to distract her from her questions. I didn't really have an answer. It would happen when it happened.

That was about all we got done all day afterward, waiting for us both to be in the mood again and fucking somewhere new. Not making for a productive day exactly, but an extremely fun and memorable one for sure. Cementing our new connection beyond any kind of doubt.

****

Nova and I were already obsessed with each other. That hadn't diminished even a little since we started having sex. If anything, we became even more inseparable than before. Clingy, even.

It made sense. First person we each had sex with, first person we each fell for, and the omnipresent fact of our sibling relationship firmly in the mix.

"So here's the thing," Nova told me one day while she was stretched nakedly out on my bed.

"That sounded dangerous," I remarked, running my fingers up and down her back. Her smooth, bare back that I found myself entranced by once again. My little sister was endlessly fascinating, physically and otherwise.

"You remember how I mentioned about wanting to make sure I had new and sexy plans to make sure you stayed interested in me?" Nova asked.

"I recall something of the sort, yes," I said.

"I really do believe I was overthinking things," Nova said.

"You were," I said. "But I mean... make notes of those ideas anyway. Just in case."

Nova giggled. "You horny thing. You cummed in me three times already today."

"So what, you think I'm done with you?"

"Nah," she said, flipping through her notebook. "I haven't recalculated the stats, but I believe the average lately is slightly higher than four times a day."

"Damn, I'm impressive," I said.

"You're horny," Nova corrected. "And enamoured with me."

The latter was stated nearly as a question.

"I am," I confirmed, just in case she was fishing. I found it cute when Nova looked for reassurance. I would have thought she'd know my intentions well enough by now. "Absolutely smitten."

"Good boy," she said, making a tick in her book.

"Nov?" I asked.

"Hm?"

"You aren't counting how much praise you give me each day and determining the optimal outputs, are you?"

"... no?"

I smacked her butt, making her yelp and glare at me.

"Bad girl," I told her.

"Am not! I'm increasing efficiencies," she said.

"I don't need trained like a puppy," I said.

She chewed her lip.

"I don't!" I insisted.

"I mean... it kind of works though," Nova said. "Praise and treats go a long way with you."

I flipped her on her back, biting one of her nipples in rebuke. She only liked it though, and I alternated between nipping at each of her tits until we were both horny and ready to go again, and I slipped into my sister's welcoming little pussy.

"See how well that works?" Nova purred.

"That wasn't praise or treats," I said.

"You made the mistake of thinking those were the only tools I was using," Nova teased, eyes gleaming.

"I can't tell if I love how scientifically minded you are about all this," I said, "or if I hate it."

"Little of both works surprisingly well," Nova said. She nipped at my ear. "Fuck me good, big brother? I need it."

I did fuck her good. I was learning so much about exactly what she liked and what got us both off. I maintained that the way I learned was better and less clinical than her extensive note taking, but honestly both approaches seemed to work and led to us having an amazing time.

Nova held me close after we'd both finished. We were pretty cuddly anyway, but sometimes she needed more than usual.

"So like I was saying," she said after a time.

"Yes?"

"Originally it was intended as benefits all round. Getting Skye and Aurora involved." Nova shrugged. "I don't think I need their help with you necessarily. Not anymore."

"You don't," I said. "You've got it figured out."

"Mmhm. But the thing is... they keep bugging me about you. About sharing some more."

"Oh?" I said.

"Hehe, I felt you twitch," Nova said. "You're so predictable."

"Be nice," I said. "And... go on?"

"You like having them interested, don't you?" Nova teased.

"Well... yeah. It feels nice. Are they really bugging you about me though?"

Nova shrugged. "To be fair, I encourage it. I wanted to make sure they were interested for when I needed help. Which I don't anymore. But... we kind of had this plan to all be able to try some stuff out, and I think they're still hoping for that."

"You mean..."

"Sex," Nova said. "They've liked getting licked out. Or playing with your cock. But sex is kind of the scary step to take."

"It doesn't have to be," I said.

"No, exactly," Nova said with some amusement. "With the right person, the right circumstances..."

"It's very flattering to be the right person," I said.

"Mmm, I'm sure," Nova said. "Here's the question, are you going to get too smug and unmanageable if you help out Skye and Aurora like you did me?"

I was hardening again, and Nova could most definitely feel it. "Me?" I asked. "Smug? Unmanageable?"

"So yes, then," Nova giggled. "That's ok, I think. I like when you're more confident anyway. Makes you more fun in bed."

I slipped back inside my sister, fucking her so very slowly and gently. I didn't need anything more than that right now, but just being in her felt really nice.

"How are you going to feel if I'm your friends' first times too though?" I asked. "That's not going to bother you?"

"I... don't think so," Nova said. "I'm curious how I'll feel about it. I think it would have bothered me if it had been one of them before me. But I'll always know I had you first."

"It might still bother you anyway," I said. "I think I'd be bothered if you fucked any of my friends."

"Hehe, so territorial," Nova laughed. "I can see that. You're a jealous brother, huh?"

"And you're not jealous at all?"

"Hm, there's some there," she admitted. "If you went and started dating someone, there'd be hell to pay."

"Noted," I said.

"But... this isn't any of your idea," Nova said. "It's different. It was my plans, and I could cancel them if I wanted to. I'd like to share with my friends. Feels like the nice thing to do. Get them some experience too after they helped me out."

"Share me, huh?" I said.

"Yeah. At least once," Nova said. "Maybe more than that, depending on how it goes."

"And you really don't think you'll mind at all?" I asked.

Nova thought about it. "I might," she finally decided. "A bit. Which will be good information to have if that's the case. Might be a good thing to test under controlled circumstances actually."

"Nov, these are your feelings. Not just scientific curiousity."

"It can be both." She nipped at my shoulder. "Plus it could benefit me just being able to observe sometimes from the outside. I've already found that to be helpful even with just messing around."

"Is that so?" I asked. "Nothing to do with you enjoying it?"

"Ah! Well maybe," Nova admitted. "Maybe I like it some. Especially when I know that really you're all mine and I get you whenever I want."

"That's true," I said. "And... I'm not opposed to the idea of sharing."

Nova whispered in my ear. "Oh? You don't mind having three pussies to cum in instead of one? You don't mind being three girls' first times? You don't mind having three horny little sisters to play with? You--"

I groaned, shut her up with a deep kiss, and came inside her again.

"You don't... play fair..." I panted.

"And I will never claim to," she said happily. "So we'll give it a try?"

"Yeah, Nov, let's try it."

****

It didn't actually happen right away. Skye and Aurora came over a few times, and we got up to plenty of naughtiness, but it took some build up before we took it further than before.

I in fact had my face buried in Skye's cooch when she made the request. She only had a tank top on by that point, and looked at me with eyes that were a particular mix of adoring and calculating. Not unlike the way Nova often watched me.

"Hey, big brother?" Skye said softly.

I knew something was coming. The girls all rather enjoyed that they could get almost anything they wanted from me when they talked like that to me. Nova, the little imp, encouraged it. She found it funny, and possibly even hotter than I did.

"Would you want to... have sex with me?" Skye asked, just a touch tentatively.

I glanced at Nova for confirmation. She was mostly naked. The dress code when we all hung out was non-existent by this point, and full or partial nudity more common than modesty. Nova gave me nothing but a subtle, cheeky smile.

"Yes," I told Skye, looking straight back into her eyes.

She flushed and glanced slightly away. "Really?"

"Yeah. Of course," I said.

Skye teased my hair. "It would be my first time doing that."

"I--"

"Yeah, Sol likes taking sisters' virginities," Nova remarked casually. "Bit of a bad boy that way."

I rolled my eyes at Nova, who gave me a beaming smile in return.

Skye saved us from our stare-down. "I really like the idea of having someone safe to try it with," she said. "Obviously you're not really my brother, but... the way you were so good for Nova feels really nice. And I like that maybe you are kind of my brother, in a weird sort of way."

"Maybe like an informal step-brother," Aurora supplied helpfully.

"Yeah, like that maybe," Skye said.

I looked around between the three girls: Skye in her tank top, Nova only in some rather damp and sexy panties, and Aurora in one of my shirts and a skimpy pair of panties of her own. Nova had previously been wearing that shirt, and Aurora had taken ownership while I'd been sucking and nibbling on my sister's tits earlier. It was amazing I ever had any clean shirts available anymore between the three of them always stealing my stuff.

I did love it though. It really was like having three sister-fuckbuddy combos around.

Or... whatever Nova was. More than a fuckbuddy, that was for sure. Not a girlfriend exactly. Something.

"Chosen siblings," I decided. "At least for sexual purposes."

Skye laughed insanely. "That's the most ridiculous way to put that!"

"Am I wrong?" I teased.

She bit her lip. "No."

I picked her up off the couch and led her to my room, Nova and Aurora in tow. We got fully naked and tumbled into my bed together. Skye's eyes were shining, and she panted softly even before we'd really done anything. To be fair, we'd essentially been engaging in foreplay all afternoon already, and her pussy was freshly warm and dripping from my tongue-play.

"My brother," Skye tried out. "My big brother. For sexual purposes only." She giggled. "Is it bad that I like that?"

Nova bounced into bed next to us and already had her notebook flipping. "The incest angle's really been working for everyone, as far as turn-ons. It gets Sol going, and makes him cum faster and harder. I would say you're not alone."

"Are we just ignoring how much you love it?" I asked Nova lightly.

She had the grace to blush, if only softly. "You've got work to do, bro," Nova chided. "Don't be looking at me right now."

She was right. Skye was right there, naked and ready for me. Wanting me. While Nova, in surreal fashion, was perfectly content to share me that way.

I somewhat awkwardly positioned myself atop Skye. I had a better sense of what I was doing thanks to all the sex Nova and I had been having, but Skye was a different person, and I wasn't quite sure what emotional things would be going on for her, let alone whether she physically reacted exactly the same as Nova or not.

I was quick to realize I was overthinking things. Skye gasped contentedly as I sank into her and happily encouraged me to thrust into her wet little pussy over and over. She clutched at me, grabbed my hair, dug her nails into my back, and murmured occasional words to me, some of which I even understood.

Nova was observing closely, pen twirling idly in her fingers in between occasional notes. Aurora had slipped her panties off to play with herself.

At some point Skye let go of me and reached out to her friends. Nova set her notes aside to hold Skye's hand, while Aurora switched hands she was rubbing herself with so she could do the same. Sharing the moment and offering reassurance and comfort to each other.

"Not so bad, is it?" Nova said quietly.

"Not bad," Skye agreed. "Good. Nice." A wide grin overcame her lips. "Really nice."

"Wait for the cum," Nova advised.

"His or mine?" Skye asked.

"Either, honestly," Nova said. "Both."

Skye whimpered softly as I kept thrusting into her. We were both feeling good. So good. And Nova was right there watching and waiting for us to cum together, which was absolutely crazy, but that was my sister all over.

Aurora was actually first to cum, rubbing her cute little pussy next to us. I found that really hot, even while balls deep in Skye at the time. It got me fucking Skye harder, making her moan deeper and louder.

"You should cum now," Nova advised Skye. "Cum while your bro-ther is deep inside you. Be a good girl. A good little sister, ok? Cum for him. Cum for us. We want to see it."

Skye cumming on my dick was so satisfying, and felt incredible the way her pussy squeezed me tighter. I didn't last much longer before unleashing inside her as well, filling her with cum for the first time.

Nova was quick to get back to her notes as soon as Skye returned her hand to her.

"The incest kink is really, really working for us," Nova said out loud. "I'm curious now how prevalent that is."

I sighed theatrically. "How many people am I gonna have to fuck for you to get a good sample size?"

Nova glared at me. "Technically... a lot. In reality we're going to make do with the people in this room. And don't you--"

"Kidding, Nov. Kidding," I said. "I actually like that you can in fact get jealous though. Feels nice. Um... and I recognize the irony of saying that while I'm still buried inside your friend right next to you."

"I'm not jealous!" Nova said. "Not exactly. I mean... it's different." She nudged my shoulder. "Anyway, my turn!"

Skye shrugged and graciously allowed me to roll off of her. Nova was on top of me almost before I'd finished moving, already rubbing herself on my cock through her panties.

"You sure you're not jealous?" I asked. "You need to take those panties off by the way."

Nova proved me wrong, tugging her underwear aside instead so she could slip me into her pussy. It hadn't taken much for her to get me fully hard again, and I loved how quick and needy she was about taking me.

"I just... I need you to be mine again right now," Nova said. "It's not about jealousy. Just... I need you."

"It's ok to be jealous," I told her, grazing my fingers up her sides. "It's kinda cute actually."

"It is rather," Skye agreed, having turned to Aurora for post-sex cuddles. She lay back against Aurora and let her friend hold her for comfort. "I get it though. Makes things different knowing your brother cummed in my pussy now, huh?"

Nova let out a small gasp and rode me harder. "Maybe."

"But you think it's kinda hot too, don't you?" Skye teased.

Nova blushed and looked away from everyone else. "Maybe," she repeated.

"Hehe, get your brother cummies, Nov," Skye urged. "We can be slutty sisters together."

"Oh my goddd," Nova whined. "You're taking to this way too easily."

"You love it," Skye said.

It was true. My sister had multiple thoughts and emotions happening, that much was clear to me. But she did love the things Skye was saying, and she was at least a little jealous and possessive right now. These things all seemed true.

I actually really liked that Nova needed me to be hers right now. The feeling of being so needed at times was one of the things I loved most, and I felt it strongly in this moment.

I surprised Nova by flipping her over, nearly accidentally sending her tumbling off the bed, but mainly just getting her on her back long enough to yank her panties off. She looked at me with a mixture of stunned confusion and excited lust.

"On your knees," I said.

Nova's eyes flashed and she rolled over, getting to her hands and knees. I pushed her shoulders down so her face was on the bed and her ass sticking up. I slid back inside her, grabbing her hips to really make the thrust go deep.

"Oh fuck," Aurora whispered, watching with wide saucer eyes.

"I know, damn," Skye hissed back.

Nova whimpered and arched her back cutely, pushing back against my thrusts, wanting my attention and knowing I was all hers for now.

"I love you," I said. "So much. So very much."

Nova nodded and squirmed. "Cum deep in me, ok?"

"Fuccck, Nov," I panted. "Not yet, jeez."

"Unf. Well go harder anyway."

"Ah, goddamn..."

Nova was really laying claim to me. She slammed her ass back against me almost as hard as I was already fucking her. She'd never asked for it so rough before. I hadn't think she wanted or needed that until now. Maybe every now and then...

It was stupidly hot at any rate. Absolutely pounding the shit out of my sister in front of her friends. Nova panting and whimpering for more, murmuring filthy but loving things every now and then.

"You need... to cum first," I told her.

"Me?" Nova asked.

"Yeah. I don't want to cum until you do," I said.

"Unf. Not fair," she complained. "You're going to cum so soon!"

I grunted affirmatively. She was correct. "Better make it fast then, or I'll have to cum somewhere else."

"Mean," Nova complained. "So mean."

Her hand flew to her clit anyway. I couldn't see what she did to herself between her legs, but I watched her arm shaking and heard the distinct change in pitch of her cute little moans.

"Good girl," I said. "Cum for you brother. That's a good sister. You'll get my cum if you're really, really good for me."

Nova became an absolutely incoherent mess, somewhere between protesting her treatment and fairly melting to it. She loved it though, I knew that no matter what she said.

She did, in fact, cum for me. I wouldn't have been able to hold out much longer, and was glad that Nova came before then. I would have cummed in her anyway. I wasn't about to actually be so mean as to deprive her of what she needed. But I got to fill her pussy while telling her what a good sister she was, and we both collapsed together on the bed.

Nova happily let me squish her under me, holding my hand and grinning to herself.

"Good girl," I told her. "Good sister. So good."

"Mmhm," Nova mumbled. "That was... intense. I liked it." She wiggled beneath me. "Bite my neck a little? Make a mark?"

I snorted softly in amusement, but did as she asked. Nova gasped and purred as I bit her. She wanted a mark, to be claimed more than she already was. I could give that to her.

Nova was eventually sated. She was very contented with her brother-filled pussy and the bite-mark on her neck that she examined carefully in her phone camera to make sure it was obvious enough. She was fairly clingy for a while after, and made me hold her close, even while she was checking out her neck and pussy in the aftermath, and flipping her notebook open to continue her scientific explorations.

"All better now?" I teased.

"Yes, actually," Nova said. "I wasn't jealous, just for the record."

"Hehe, it's ok to be," I told her, playing with her hair.

"I might have been possessive, if anything," Nova said. "And horny."

"Definitely horny," Skye laughed. "Damn when you get horny, you really get horny."

"It was pretty hot," Aurora said. She and Skye had switched up positions a little to where Skye was sort of curled up against her, but leaving Aurora lots of room to play with herself.

"I think I like you being possessive," I told Nova, kissing gently where I'd left the mark on her neck.

"Only because the solution was more sex," Nova said.

"Well... yeah, that helped," I agreed. "You know I love you as much as ever, yeah?"

She squirmed happily in my arms. "Yeah, I know."

"You feeling ok with everything?" I insisted.

Nova took a moment to think about it. "Yeah," she finally said. "I am. I want to see you have sex again. See if I have the same feelings. I liked it, but it made me feel some complicated things inside. It was neat, actually. But I really needed to feel that you were mine afterward." She clicked her pen thoughtfully. "I want to experiment with that more."

"Ha, everything's an experiment, huh?" I teased.

"If one is brave enough, sure," Nova agreed seriously. "And... I do want everyone to be happy." She looked at Skye and Aurora.

Skye smiled back. "I'm pretty happy."

Aurora nodded more shyly. "I... want to try it still. It looks like it feels good."

"Of course," Nova said. "Any time. Would you... mind getting some waters for us though?"

Aurora blinked then hopped out of bed. "Oh right, hydration. Good idea."

I sighed to myself watching Aurora scamper away wearing only my shirt and nothing at all underneath. I honestly wasn't sure sometimes whether it was full nudity or the barest pretense of modesty that was hotter, but either way I was seeing plenty these days.

Aurora returned with an armful of bottled water, doling them out to the lot of us. She hopped back into bed while the rest of us drank thirstily. She pulled her knees up to her chest and rested her chin on them, apparently lost in thought. I decided not to point out that her pose left her pretty little pussy peeking out, giving just the smallest glimpse of it between her thighs, where her shirt didn't sit quite low enough in her current pose.

For that matter, I had Skye to check out too, all splayed out nakedly as she was. And Nova in my arms, warm against me, free for me to feel up. I cupped her tit in my hand and she carried on her deep note taking like I wasn't even there.

I'd finished inside Nova and Skye already, filled both pussies with cum, yet I could already tell I was going to get horny again. How could I not, really?

"I need to pee," Nova finally declared, setting her notes aside.

"Yeah, me too," Skye said. "I've been holding that in a while now."

"Well you shouldn't," Nova said. "Not after sex."

"I know," Skye said. "But I didn't want to miss anything. Not like you were going to record it for me."

"Ooh, that's a thought though," Nova mused as the two of them sauntered out of the room together. "That would be better for reviewing afterward. The problem with my notes is it's only what I observe and remember in the moment, and..."

Her voice trailed out of hearing distance, still excitedly yapping about possibilities. The sight of both cute asses swaying out of the doorway was seared into my short-term memory.

Aurora was staring at me all the more piercingly when I looked back her way. The intensity of her gaze actually made me blush a little, despite the fact that shyness and shame were becoming foreign concepts to me.

"Doing ok?" I asked her.

"Yeah," she said. "Do you want to have sex with me?"

I blinked at the sudden transition. "Um... now?"

"Yeah," she said. "I want to try it. Nova and Skye both loved it. I... don't want to do it with them staring though. Seems like too much."

I glanced at the doorway. "They're only going to be a few minutes probably."

"I know," Aurora said, crawling at me lightning-quick while my head was turned. Her hand contacted my cock, rubbing softly and with undisguised interest. "But I think... it's kind of just starting that makes me nervous. I think it would be fine after that." She looked at me with big eyes. "Do you want to try it with me, Sol? Please?"

"Unf, well yeah, I mean I--"

"You want to have sex with your little sis-ter?" Aurora added, batting her eyelashes.

"Fuck's sake," I groaned. "Why'd Nov have to teach you that?"

"You get so hard for things like that," Aurora breathed. "So hard in my hand."

I nodded. "I know. It... it works for me. I'm not saying it doesn't. Just... it's kind of excessive, isn't it?"

"Please big brother?" Aurora continued heedlessly.

I was helpless against her. As helpless as if she was my real sister as much as Nova was. Totally done for by only a few carefully selected words.

I tugged her shirt--my shirt, really--over her head. "On your back," I told her. "Like a good sister."

Aurora complied breathlessly, eyes shining, bottom lip held nervously between her teeth. "Please," she said. "Before they come back. I'm... I'm ready."

I nodded. I felt her need and urgency even beyond her words. It made sense to me, even if privacy wasn't something I particularly got in my sex life and I didn't find it to be so crucial for me. It was for Aurora, at least to start with so she claimed.

"You want your brother in you?" I asked, just to check, just to be sure.

Aurora smiled at the way I phrased the question. "Mmhm! I'll be good. I promise."

I groaned softly and pinned her legs back, hefting them up over my shoulders as I pressed my cock against her soaked pussy. Aurora gasped and squirmed, but did her best to hold still for me, making burning eye contact with me the whole time.

"Yes," she whispered. "Yes. Now. Please."

I sank into her, disappearing into her wet little slit. Aurora made an animalistic whimper, then let her mouth fall open in a happy, gentle pant.

"Oh wow."

"Good?" I asked.

"Mmhm," Aurora said. "It's a lot. But good, yeah. You can... move. Do the... you know."

I tried pulling out and back in a few times.

"Better?" I said.

"Yeah. Yeah good," Aurora murmured. "Thank you." She grinned wider at me. "Big bro-therrr."

I snorted amusement and thrust harder into her. I stayed relatively gentle, but found that she did seem to like it when I got into a quicker rhythm, in and out.

"You... feel good too," I told her.

"Good," Aurora said. "You can cum in me when you want to."

"What's this obsession with skipping right to that," I protested weakly, feeling the thrill of the way she said it with such casual conviction.

"I dunno. Everyone else is doing it," Aurora said.

"Doing what?" I heard Nova ask as she padded back into the room.

"I head something about cumming," Skye said. "Are you... ah! Aurora! Without us, even!"

"Bad friend!" Nova laughed, bouncing back into bed. "Bad girl!"

"I'm nottt," Aurora whined. "Just... it was too much to do it with you both watching. I needed a head start."

"I get it," Skye said. "Nova's so intense."

"Me?" Nova protested. "What about you?"

Despite their squabbling, Nova and Skye took up flanking positions on Aurora, going with tradition to hold her hands on each side. Aurora accepted the gesture, apparently fine now that we were mid-sex already.

"Better cum good in her, Sol," Nova told me. "Now that you've started and all."

"Do my best," I said. "Am I going to need to be ready for you again right after?"

"Hm, maybe I'll let you have a little break first this time," Nova said. "But just remember you're going to need to take care of me good if you want to go about fucking my friends whenever you want."

"Literally all your fault," I told her.

Nova tried an innocent look on for size. "Who, me?"

"Hehe, he's right though," Skye laughed. "You did this."

"I did, didn't I?" Nova admitted. She stared down at where my cock was thrusting in and out of Aurora over and over. "It's kinda sexy, isn't it?"

"Very," Skye said. "I am, in fact, going to take your brother for a lot more rides going forward. Just so you know."

"I know," Nova said. She clicked her tongue thoughtfully. "It really is hot thinking about it. And watching it." She gave me an adoring and needy look. "Tell me how much you love me again? I like when you do."

"I love you so fucking much," I told my sister, meaning it utterly.

She leaned in to make out with me, and I felt the absolute absurdity of expressing such love and desire while I was also balls deep in her friend. I knew Nova needed it right now though, and nothing about the circumstances changed how I felt.

"You mean so much to me," I told Nova. "Nothing's ever going to change that."

We sloppily made out some more.

"Good," she eventually whispered in my ear. "Now... be a good brother and cum in your sis-ter, ok? She's waiting for it. She's being so good. You need to cum in your sister's pussy. I know you like doing that."

"Every... time..." I panted while Nova nipped at my ear and neck.

It worked though. That was what made it hard to complain. Nova told me to cum in my sister's pussy--pretend or real apparently didn't matter that much--and that's all I wanted to do.

"Good boy," Nova urged. "Cum for me. And for her. All your little sisters want you to right now. Do it. Be a good boy."

I whimpered softly and buried myself in Aurora, cumming deep in her. Just like she wanted, just like Nova insisted. I finished the job of making sure all three girls in bed with me had filled up cummy pussies.

Aurora was pretty clingy afterward. All she wanted to do was curl up and cuddle with me, to the point that Nova didn't even bother trying to detach her for a while.

Nova and Skye snuggled up together instead while my sister pored over her notes, occasionally jotting some new piece of information down.

"So we're ahead of projected schedule now," Nova said. "With, I would say, better than expected results."

"I'm proud of Aurora getting in on this," Skye said. "I thought you'd take longer to work up to it."

Aurora shrugged, but didn't otherwise move. "It felt right."

It was just as well I'd finished three times already. Being so casually close and intimate with the three of them while they all remained naked would have had me too horny to function otherwise. As it was, I could just enjoy it. Though admittedly, they worried me the way they talked about some stuff.

"What exactly do you mean by schedule?" I asked.

"I wouldn't worry about it," Skye said with a teasing grin.

"Only a projected timeline," Nova said, fluttering her hand dismissively. "We'd scheduled Skye for losing her virginity today. Aurora was more of a wild card."

"Didn't know for sure ahead of time," Aurora mumbled, then hugged me a little tighter.

I shook my head. "You're all kind of fucked, huh?"

Skye grinned wider. "We are now."

"Not what I... nevermind," I sighed. "Why do I feel like I'm the least involved in any of the planning stages for these schemes of yours?"

"Probably because that's a fair assessment," Nova said seriously, though she crawled over to sneak a kiss with me, which did in fact mollify me a bit. "Would you like to know about our next steps?"

"... there's more?" I said.

"Hopefully lots more," Nova said.

"Hopefully," Aurora echoed sleepily from my chest.

"But problem is our parents are coming back in only two weeks now," Nova said, twirling her pen as she stared intently at her notes. "And that would really put a damper on our experimenting."

"You don't have to just call it that," I said.

"Experimenting?" Nova asked.

"Yeah," I said. "It's not all just experimenting."

"No, it's not," Nova said. "But I think we could probably still sneak in lots of sex and cuddles, if that's what you mean. It's the, you know, group fun, having us all hanging around naked together. That kind of stuff would get very, very limited."

I blinked as I thought about it. "Oh. Oh yeah." I looked down at Aurora in my arms, and at Nova and Skye stretched out nude and cat-like together. "I'd miss that, I think."

"Exactly so," Nova said. "So we started... scheming."

"Started?" I said, arching an eyebrow.

"Kept scheming then," Nova amended smoothly. "We're tentatively thinking about getting our own place." She tapped her notebook with the edge of her pen. "I've looked into pricing and the size of rentals available. It's doable."

"Oh really?" I said. "Should I be worried about waking up somewhere brand new one morning?"

"No, silly," Nova said. "We would all have serious talks about it before committing. There's so much to figure out first too. Like ideally we'd have a lot more time to see how we all feel before taking a big step, but as I say we're on a bit of a clock before a lot of the fun gets shut down."

I slowly rubbed Aurora's back, up and down. "How much of this was planned before you ever seduced me?" I asked.

Nova pouted at me. "I did not seduce you."

"You did."

"Didn't! That was never the plan. Well... until it was, I guess." Nova chewed her lip. "I don't know, things changed. A lot. I like how they went, though."

"Yeah, me too," I said, earning another kiss from my sister. "Love you."

"Love you too," she replied easily. "And... I don't want to have to be super subtle about it all the time. So new place, I think. Though there'd be a lot of logistics to work out. And it might be a disaster."

"When has that possibility ever stopped us?" I asked.

"Well exactly," Nova said. "You get it."

****

We hung out the rest of the day together after finally leaving the bedroom again. I was heavily discouraged from wearing clothes at any point, and the girls either stayed nude as well, or else wore one of my shirts and nothing else.

I had a constant reminder all day that all three of them were cum-filled. Even when they weren't deliberately mentioning it or flashing me directly, there was pretty consistently one or more pretty, bare pussies on display one way or another.

If I was sitting down at all, I nearly always had one of them in my lap. Aurora more often than not, in fact. She was still clingy, and didn't seem to mind making it obvious.

Nova and Skye distracted each other plenty with planning and scheming. There were many details to be worked out, but it became clearer and firmer that we were all at least going to try moving in together. Somewhere with a modicum of continued privacy from the outside world, even if it wouldn't be as nice as having the full run of our parents' place while they were on vacation.

I half-listened to the details while spending much of my time cuddling and feeling up whichever girl was currently in my lap. Nova mostly ignored me as long as I didn't interfere with her notes or try to peek at them. Skye actively encouraged me. Aurora played a more teasing game of making me work for it. She'd let me slip my hands up her shirt, but only if I moved slow, and sometimes she'd slap my wrist away for no reason at all that I could fathom. Then at other times, I could be fully cupping her tits or knuckle-deep in her messy pussy and she'd only moan in soft and contented fashion.

It all kept me amused anyway, and quite aroused despite all the previous cumming. Nova eventually climbed on my cock when she judged the time right and rode me to an unhurried orgasm for both of us. Doubling up on the cum inside her and making her feel better about sharing me.

"I still kind of like when you're a bit jealous," I said.

"Possessive," Nova corrected once again. "I'm a bit possessive sometimes. I think that will fade with time. We'll keep an eye on it."

Despite her claims, she monopolized my lap for a while after that, including lying her head on my shoulder and just happily relaxing against me for quite some time.

We all went to bed together that night. Pretty well what I expected by then. It was cozy, but harder to actually sleep with three other bodies around all shifting and making small noises.

I wasn't surprised about sleeping together, but I hadn't quite expected how much Skye and Aurora would stick around afterward. They didn't quite move in as such, but if they went home it was only temporary, and often just to pick up some more clothes or supplies.

It took me a few days to actually ask about Skye and Aurora staying over so much. I didn't want to jinx it at first, since I really liked having them around. It was a bit much always being outnumbered, but it almost universally worked out for me in all the best ways.

"It's important to make sure we can cohabitate nicely," Nova told me. "No point going through all the trouble of moving in somewhere and then finding out we can't stand living together."

"Always two steps ahead, aren't you?" I said.

Nova grinned enigmatically. "You know I like my research."

"Ha, yeah, I know."

"Speaking of which..." Her fingers tickled down my front, brushing tenderly along my cock.

"Is that what we're calling it now?" I teased. "Research?"

"It's always been research," Nova said as she wrapped her hand around me. "Just... it can be other things too."

My sister was, perhaps, the most insatiable of any of us. Always finding the slightest excuse to fuck some more, or otherwise try out various sexy activities. It was some combination of horniness, possessiveness, jealousy, love, and a genuine desire of hers to try new positions, techniques, or kinks.

It wasn't really a fair contest. I didn't have the same opportunity to truly develop urges. Having all three girls around saw to that. The huge upside was that I always had someone to have fun with when I wanted.

Interestingly, once the initial novelty wore off, Skye and Aurora didn't demand as much of my sexual energy as I expected. Skye still wanted to get off regularly, one way or another, but not with the same dedicated enthusiasm that Nova showed.

Aurora became more of a cuddle-slut than anything, monopolizing me far more often with her head nestled cozily against me rather than with my cock inside her. Her need for snuggles got even stronger after being intimate in some way, however.

The truly rare thing in my life right now was privacy. I'd only just barely gotten balls deep in my sister when Skye flounced in, sprawling out next to us with a dramatic sigh.

"Picking up these extra shifts at work is getting to be a drag," Skye complained. "I got next, by the way."

Nova giggled. "Fair. We only just started though."

Skye shrugged. "That's fine. Gives me time to unwind first anyway."

Skye lazily watched beside us as Nova and I fucked. She slowly unwrapped herself from her clothes, getting naked and wet in preparation.

I could have sworn sometimes that Nova actually preferred an audience. She got more into it, digging her nails in and biting at my shoulder, whispering filthy things to me, rocking her hips back more aggressively against me. It was either the thrill of being watched, or jealously making sure to leave her mark on me before her friend got a turn. Probably some of both, really.

"I suppose I'm just a performing sex toy for you all now, huh?" I said, making sure to bottom out a little harder inside Nova's sweet pussy.

"Unf, no of course not," Nova purred. "You're our big brother." Her fingers scratched lightly at the back of my neck. "You need to take care of your little sisters, that's all."

"Hehe, that's right," Skye said. "You got 'sponsibilities toward us. Brotherly duties and all."

"You two are fucked," I said.

"With any luck," Skye agreed.

Nova grinned and kept teasing and encouraging me until I came in her, pumping her pussy full of cum.

Aurora padded in just about in time to watch Nova get filled up. She was entirely nonchalant about witnessing the sibling creampie in progress. It had become a regular occurrence, along with the aforementioned lack of any kind of privacy between us. She was, too, wearing one of my shirts and little else, as was her wont these days.

"I already got next," Skye warned as Aurora made herself comfortable too.

"Of course you do," Aurora sighed.

"Aw, are you horny too?" Nova asked, sliding her hand over her pussy as I pulled out, leaving her messy with my cum.

"Nah," Aurora said. "But I was feeling lonely."

"Want to cuddle while Sol and Skye fuck?" Nova offered.

Aurora squirmed awkwardly and shook her head.

Nova poked her teasingly. "Want your big brother?"

Aurora shyly nodded.

"Don't worry," Skye said. "I'll be quick. Then you can have him."

"You'll make a boy feel cheap passing him around like that," I said.

Skye rolled her eyes and stuck my cock in her mouth, ignoring the mixed flavours of me and my sister and purposefully bringing me back to life.

"I don't think she's worried about that," Nova supplied helpfully.

She had cuddled up with Aurora anyway, and already had her notes back out. She was still obsessed with keeping records, but I was noticing that over time the actual quantity of writing was dropping pretty hard. I was tempted to suspect that my sister was settling in to having everything she wanted, and didn't have nearly so much need to experiment. At least day to day. I knew we'd keep finding new and interesting things to try out.

Skye rode me hard until we both came. Nova and Aurora cozily watching and chatting the whole time, both amused as Skye got off my dick and spilled some of the mess upon her dismount. She was very quick to lick up the stray cum off me though.

Nova and Skye both pattered off after, naked and satisfied, while Aurora happily glommed on to me for some cuddle time.

"I really like having you for a brother now," Aurora told me softly.

"I'd been getting that impression," I said.

"That's ok, isn't it?" she asked. "We could have sex more if you wanted..."

"Haha, no, I'm getting lots," I assured her. "And... I really like having you as a sister too."

Aurora smiled broadly and blushed profusely all at the same time. After a few minutes she started toying with my cock. Really just playing with it, not for any specific goal.

"It's just fun," she said in response to my questioning grunt. "I like when it's soft and then... gets hard. It's neat."

She wasn't wrong, exactly, but it was kind of fascinating to know her well enough to understand that she truly didn't have sexual goals in mind beyond just snuggling and playing with my cock for her own amusement.

Aurora was still messing around with me when my phone rang. The fact that it was my mom didn't slow Aurora down at all. She seemed even more amused to play with me while I picked up the call from my mother.

"Hi, baby boy," Mom said.

"Hey Mom," I said. "How's it going?"

"Good! Really good."

She launched into a spiel about what her and dad had been up to lately. I half-listened while glaring warningly at Aurora, who naturally ignored my cautions entirely and continued teasing me to her heart's content.

"Anyway," Mom said, "I did have a point in mind."

"Yes?" I said.

"You know how we're scheduled to be back home soon?"

I nodded and composed myself before answering affirmatively. I was really going to miss the freedom we'd had of the house lately. The girls were a handful, but I loved them and all the mischief we got up to. It was going to be a bummer having that disappear, even if we did have adequate plans coming together eventually.

"Well... would you and Nova be terribly upset if we didn't come back right away?" Mom asked.

I blinked in temporary confusion. "What?"

"It's only... your father and I have been having such a wonderful time, and his boss actually okayed him to work remotely, and I have a little more vacation I can burn, and then..."

I listened to Mom explaining herself while a slow, all-consuming grin spread across my face. She thought Nova and I would be upset? Yes, we'd miss our parents, but this was perfect actually.

"... and you and Nova can take care of yourselves, I know you can," Mom said. "I just don't know when we'd get another chance like this."

"Mom, Mom, it's good. It's really ok," I said. "I wasn't expecting it, but yeah, of course stay longer if you have the chance. We'll be fine."

"Thank you," Mom said. "I was sure you'd be ok with it, but I do worry sometimes. You and your sister are getting along ok? Keeping out of trouble? She's mentioned having friends over lately, they're not in your space too much are they?"

I looked down at Aurora, felt her warmth against me, her hand on me, observed that cute look of concentration on her face. I thought of how it felt to be deep inside my sister, cumming in her every day, often more than once. I thought of the rampant nudity, and the recently extinct concept of ever having to sleep alone.

"We're managing somehow," I assured our mother.

"I was sure you would be. You take care of each other, ok?"

"Yeah Mom. Nova and I'll take care of each other."

Aurora was shaking with laughter by the time I hung up the phone. "I only heard your half of that," she said. "You were being bad."

"Wasn't," I said.

"Taking care of your sis-ter?" Aurora challenged. "You didn't elaborate on that, I noticed."

"Yeah, well, I didn't mention I have multiple sisters to manage now either."

Aurora shrieked as I ran my fingernails up her side. We tickle fought for a few moments before she rolled away from me panting.

"So... we have more time now?" she asked.

"We do," I said. "Want to come tell Nov and Skye with me?"

Aurora nodded enthusiastically, making sure to hold my hand tight as we made our way to find the others.

We didn't quite get the chance to reveal our newest granted boon. Nova was already on the phone with our mother, and from what I overheard the surprise had already been revealed.

It was a bit of a naughty situation, the girls being naked while Nova casually talked with Mom and assured her that everything was fine at home. It got even lewder when I bent my sister over and stuck my dick in her while she was conversing.

Nova did her best to carry on as normal while getting fucked by her brother. Her friends were no help, as they spent all their energy repressing giggles at her predicament.

"No, Mom, Sol and I are really getting along," Nova said while I was balls deep in her. "You'd be surprised how well we're living together, I think."

Understatement, that.

"Skye and Aurora have been hanging around too," Nova said. "No, Sol's not bothered about all the feminine energy. Want him to tell you so? He's in the middle of something I think, but he could..."

Nova whimpered softly and had to hold the phone away from her mouth for a second as I rubbed her clit while thrusting into her wet pussy. She glared at me for a second before finishing up the call as quickly as she could.

"That was... so bad!" Nova said.

"Sorry," I said.

"You're not," she said. "But... that was hot. Unf. Someone remind me we need to try that again. I need to write that down." Nova stared intently at me over her shoulder. "Now make me cum. You owe me."

It was a fair point. I did owe her. And I wanted to anyway.

"Anything for my sis-ter," I told Nova seriously. "Be a good girl and cum for me, ok?"

It took a bit longer to get her off, but only a bit. She was pretty wound from the phone call already. I'd actually only meant to have some fun with the situation, on a whim as much as anything, but it had genuinely been pretty hot for both of us.

I came inside her again too, of course. I wasn't going to skip out on that.

We held each other afterward, aware of Skye and Aurora spectating, but not really minding at all.

Aurora, however, was visibly vibrating with excitement and could only restrain herself for so long. "So... we're staying here for a while, right?" she asked. "We don't have to find some stupid apartment for way too much rent?"

"Of course we are," Skye said, snaking her way in to the hug Nova and I had been sharing. "Big brother needs all his sis-ters around, and we need our space."

"Hehe, good," Aurora said, joining the mostly-nude group hug.

"Who says I even want you all sticking around?" I asked.

I grinned as I got booed loudly, then gasped as I got nipped at from various sides all at once. Usually only Nova bit me, but it seemed to be spreading in this case.

"Of course we're all staying here for a while," Nova said. "It solves all our problems, at least temporarily. It gives us more time to work out how we cohabitate together. It's cheap and gives us space as Skye said. And privacy from anyone overhearing the, uh, incestuous remarks flying around."

"I love that you think that's more worrisome than the actual incest," Skye teased. "Anyway, this is good, 'cause I didn't really want to go back to living full-time with my family until we had a place sorted out."

"Yeah, me either," Aurora said. She poked me urgently in the shoulder. "Anyway, it's still my cuddle time. We got interrupted."

Nova somewhat grudgingly allowed it. "We were working on food before we got distracted," she said. "I guess we should get back to that."

"I'm still hungry," Skye agreed.

I got to watch Nova and Skye figure out some snacks while Aurora and I cuddled some more. It turned into group cuddles a little later on, and even though it was quite disorganized, it was really quite affectionate and loving.

It was kind of amazing to think this had all come about from Nova's 'scientific endeavours,' but I loved that she was crazy enough to make stuff like this happen. She was probably the best little sister I could have ever had, and thanks to her I had a couple more pretty cool sisters too.

I kissed Nova's cheek, and she turned to look at me questioningly. I could tell she was confused about the gesture, but happy with it too.

"Love you," I told her quietly, just in her ear, just for her.

"Ha, silly," Nova said. She rested her head on my shoulder. "Love you too. You're the best brother." She laid her hand over her pussy. "You make me feel so good."

I held her close, feeling the subtle shifting as Skye and Aurora snuggled in tighter as well. I loved them too I realized. It was different, but it was there. My sisters. My precious little sisters.