Halloween Costume Mix Up: Siblings

Siblings are a new flavor for me to explore. I intended a short but sweet and hard-hitting quick story about a colossal mistake on Halloween. I hope you have fun and thanks so much for taking the time to read my work!

Halloween was the best holiday for the family. Every year Sierra and her brother Ash made a point to go to Grandma and Grandpa's house. They lived in a great neighborhood for trick-or-treating. Sure, she was 18 and he 19, and some said they were too old for it. Halloween was about fun with friends and sure, they would go get some candy, but at this age, there were other treats in the plans.

Ash's girlfriend Madison was going to come over and meet them. There was a chance she would be early, and Ash told her to go up and change in one of the spare bedrooms. Hopefully, he wished, she would be waiting for him. Likewise, Sierra's boyfriend Chance was also coming over. They all had agreed on superheroes as this years theme, but for more fun they had agreed not to say who they were coming as. Sierra chose the Pink Power Ranger, and Ash chose Spider-Man.

Sierra was with Chance almost constantly, swept up in youthful love. She was feeling so aroused at the thought of spending the evening out with a possibility of finally doing more with him. She was tired of being the good girl. What if she did something wild like surprise him with some dirty, risky sex right there in Grandma's house? She didn't know what everyone else was doing, but they are always running late. it might give a window of opportunity with Chance.

Ash had been entranced with Madison, and tonight was a perfect opportunity to go farther than they had. The anticipation made him tingle; he felt heavy with arousal. The hormone-fueled desire to mate kept him in a constant state of edging. What if he did something really risky and dangerous? What if he saw her in the spare room wearing her cute costume and just took her? He had visions of passionate, risky sex.

The afternoon was growing late and soon the fun would begin. Grandma and grandpa were out in the back garden picking flowers and beans, enjoying the Sun and doing this and that.

Ash headed over to Grandma's house to meet up with Madison who should have been there by now. Little did he know that Sierra was already there. She was upstairs in a guest bedroom putting on her costume. It was a two-piece top and bottom, thankfully. Having to pee with a unitard was a nightmare. The outfit was very firm-fitting, more than she was used to. It really showed her figure, hips, all of her female curves. "I hope I don't have a camel toe in this thing." She laughed as she spoke it to herself. Tugging up too hard on her pants bottoms was risking showing the world her kitty. She pulled the mask on and posed like in superhero movies, giggling with how silly it was but excited for the fun. She was also super horny but there wasn't any time for that before the festivities began, no matter how much she wanted to rip Chance's clothes off. She walked out of the bedroom and down the hall.

Ash walked into Grandma's house. He never knocked, he was over there all the time. There he stood in the entrance, just as the Pink Power Ranger appeared at the top of the stairs. He immediately took up a superhero pose as he playfully challenged Madison to a little duel. She did some Power Ranger moves and ran down the stairs to Chance. She play-fought with him, and before either spoke, they both glanced back to the kitchen; nobody was in the house. They had a moment and they both knew it. Sierra made the first move. She reached out and grabbed his package under the thin costume fabric. His hands felt her up and down her body. Maddie was perfect. Her firmness and form under the costume fabric was intoxicating. He grew so incredibly hard. Sierra felt him come alive in her hand. She glanced to the kitchen again and thought to herself, "God, I hope grandma doesn't walk in." Ash felt her hand grasping his now iron cock and glanced up at the kitchen again. They would have to be super quiet. There was no time for foreplay. His hand found her flat pussy and his middle finger parted her lips from above the flimsy fabric. She shuddered and became instantly wet. Her fingers ran along his length, and she was a mess of thirsty desperation.

Suddenly he grabbed her and twisted her around and pushed her down over the sofa arm. She gasped as he yanked her costume pants down. He tugged his own pants down and his well-built, girthy cock sprang free and pointed directly at the pussy it craved. They knew they would somehow have to be quiet as the sounds of sex would draw grandma's attention; yet they didn't go upstairs. Something about doing right here felt so wild and filthy.

Then she felt it. The tip of his hard dick sliding against her swollen vulva. Her lips were so silky soft against his head, almost caressing it as if to welcome it in. He rubbed his pre cum all over her beautiful lips as he gave in to the waves of electric pleasure. She was presented to him. Pussy high for easy access. He could never resist this moment. There and then, he penetrated her. She pushed her face into a pillow and tried hard to be silent, making muffled gasps through the mask and into the pillow's depths. She stretched to accept him. He pumped shallow and slow to open her. Once he felt his cock go deep enough, he pushed farther and she swallowed his entire length like a sword in its sheath. Her pussy lips were now sucking greedily at the base of his cock. He began the mating thrusts. Euphoria filled him as he felt her soaking wet vagina slide up and down his length. He couldn't last long like this even if they had more time. Glancing again at the kitchen, he felt time pressure and decided to end it. She felt him change and knew they had to finish, though she wished they could do this for hours.

Some full-length thrusts, tip to base, began to push him to maximum tension. He felt his orgasm build and began to explode with violent pulses deep inside her. She was lost in ecstasy as she felt him suddenly ejaculate. The feeling of semen flowing into her body was electric magic bliss. Such an amazing pulsing cock filling her whole body. And then it was over. He pulled his cock from inside her with a sloppy noise as they decoupled. Both were panting, and he gave her a hard slap on the ass and laughed. She was startled by the sudden sting, and she lay there over the sofa arm in a horny sex fog. Ash turned and ran up the stairs to go clean up, expecting her to follow.

Sierra stood up, and pulled up her panties to find a massive amount of semen leaking out of her greedy pussy. She pulled up her costume pants as well and got herself together. Her Power Ranger mask was wrinkled and pushed to the side from her face being ground into the sofa cushion. That laugh, so familiar like one she had heard a million times. She felt confused. Chance didn't laugh like that. After a moment of stillness and unease, she glanced up the stairs. Then came that voice. Ash called down. "Maddie, where are you?" Sierra froze and her blood ran cold. She heard the shower turn on.

Just then there was a knock. She went to the door took a breath, trying to be ready to act like she was having a normal day and didn't just get fucked by what was looking at the moment like her brother Ash. She opened the door to find Deadpool standing there. He did some superhero poses and laughed. His familiar boyfriend laugh did not match the earlier one. If Chance wasn't upstairs, and that sure as hell sounded like Ash, then... Her body felt cold. She stood still, silent.

"Well, aren't you going to let me in?" Chance asked as he pushed by her.

"What's the matter, Sierra? Don't you like my costume? I love your Pink Power Ranger." He pulled out his plastic swords and began swinging around the living room. Sierra startled.

"How do you know it's me?" She asked in a shaken voice.

"Madison just texted that she's running late. Check the group text, dummy."

Sierra mumbled something about liking his costume and not feeling well. She ran off to the downstairs bathroom in a panic.

She slammed and locked the door with a sinking feeling in her heart. She tore off the mask and stared at herself in the mirror. "Who did you just fuck? Who just fucked you?" Reality came crashing in around her and she collapsed onto the vanity. That laugh, that voice from upstairs. Her hand found its way between her legs and she wasn't dreaming. There was a hell of a lot of semen still leaking from her and her panties were soaked. She was in shock, and grabbed a towel and pressed her face into it so nobody could hear her cry. "What did I do?" She whimpered. Her body was betraying her. It was still demanding of her brain that it get satisfaction. She was denied her orgasm in the primal mating that just took place. Her vulva was still swollen, her labia still full and wet. She was full of semen but not satisfied. God, she had loved the way he grabbed a handful of her costume to hold her in place as he mated her intensely. The mix of fear, shame, and arousal was deeply potent.

Face still in the towel, she, flushed with hormones, adrenaline, and dopamine, her mind drifted to secret places. There was a closed box hidden in the shadows. Inside she kept her deepest secret, one nobody could know for her entire life. In that box she kept locked up a sexual desire for her brother. She had wanted what happened today, even if it was an accident. Everyone has this closed box hiding inside. What she kept in hers was pure fire. Now opened, she felt the heat again. She reached her hand down again. She felt the slick stickiness of semen as her finger parted her lips. Her clit was bathed in semen as she circled it with her elegant finger. Intense waves of orgasm flowed through her as she came hard against the cold tile vanity. In her mind she imagined Ash taking her like he did.

As the post-orgasm clarity settled in, Sierra knew that the second she opened the bathroom door, everything was going to come apart. She heard the front door open. Chance's voice boomed through the house: "Madison! I mean Catwoman! Fucking classic, I love it!"

She stood frozen for a second, then pulled the mask back on, hiding the mascara streaks and the still-wet, swollen look in her eyes. The only desperate hope she had left was that Ash would somehow figure it out and keep his mouth shut. That was unlikely. He was about to learn, in front of everyone, that instead of fucking his girlfriend, he had just fucked his own sister.

Footsteps came down the stairs above her. "Maddie? When did you change?" Ash's voice, confused.

"What?" Madison answered, just as confused.

Sierra's stomach dropped. Her heart hammered in her ears. She turned the lock, then slowly turned the knob.