Winter was bundled up in bed, playing his 3DS. The night was colder than usual, but he was nice and toasty in his blanket cocoon. He was naked under the blankets, and one paw kept creeping down and rubbing his little member. He wished that he still had his teddy bear, but his mom had thrown it out when she saw that it had a hole in the bottom.


Winter, of course, had made the hole on purpose. The soft, fuzzy filling of the plush bear felt good on his little cock when pubescent urges struck. At the moment, the urge was striking pretty hard. He had talked to his father about what was happening, but his father had only laughed and called him an ‘early bloomer’ and said nothing more. Winter had figured out a few things on his own, though.


He folded his 3DS and set it on his night stand and started to rub his shaft more vigorously when his door suddenly swung open. It startled him so much that he almost yelled in surprise. 


“Winter? I can’t sleep…” It was his younger sister, Summer. She never knocked.


Winter rolled his eyes and pulled his underwear back on from under the covers and got down from the bed, his semi-flaccid shaft poking out a couple inches, “What do you want me to do about it?” He started to tell her to go away, but he smelled something that made him stop. He sniffed his sister more closely, “What is that?”


She looked up at him and wiggled her hips slowly, almost as if she needed to go to the bathroom, “Mommy says I am in my first heat. My… Parts, down there… They feel funny and I can’t sleep. What did you do when this happened to you?”


Winter had no idea what she was talking about. He never smelled funny, except for sometimes now when he didn’t take a shower he smelled a little stinky. Summer didn’t smell like that. She smelled really good. The more Winter smelled her, the more his little cock grew and hardened. Summer saw his young erection and giggled, “What is that? Did you put something in your pants?”


Winter could feel his cheeks getting warm. He looked down and saw that he was fully erect. Summer didn’t have anything poking out from her nightgown, but Winter wanted to check anyway. He pulled her gown up and saw nothing underneath except for a crease between her legs. The smell hit him strong then, and he started trembling. 


He pulled Summer onto his bed and pulled his underwear off again, “Mine is different. Dad said that girls and boys have different things in their pants, but he didn’t say that girls just had a hole.” He reached out and touched the puffy, soft flesh with a finger and Summer immediately whimpered and spread her legs wider. Winter pulled back, “Sorry! Sorry! Did I hurt you? I didn’t do anything, I swear!”


Summer shook her head, “No, that felt really good.” She reached between her legs and pressed against her heat-engorged labia, causing another jolt of pleasure to run through her body, “Do that more… Rub it a little.”


Winter did as he was asked and began rubbing his sister’s groin and inner thighs. His erection grew so hard it started to hurt. He had an idea, “Summer, can I try something? I think it will feel good. I did this with my teddy, too.” She nodded silently, her hips rocking instinctively with her uncomprehended arousal.


Winter got on his knees and scooted awkwardly between his sister’s legs, “Ready?” She nodded again, this time more desperately. He lined his young shaft up to the hole in Summer’s nether region and pushed forward gently. He was afraid he was going to hurt her, but instead she gasped and nodded, a look of desperate urgency on her face. Winter felt a slick, warm sensation wrap around his member as he pushed into his sister. He could tell by her sudden reaction that she was enjoying it as much as he was.


Her legs wrapped around his rump and pulled him in faster. She arched her back and gripped his arms as she bit her lip to keep from moaning with pleasure. She had no idea something could feel so good, but her heat was begging her to keep this going.


Winter was not inclined to stop any time soon, so he went along with her motions. He thrust deep into her and felt a sensation that he couldn’t imagine was real. He thought he must be dreaming as his sister’s sex tightly hugged his aching member. He could feel the familiar explosive pleasure building in his gut, begging to be released. It was more intense than he had ever experienced before.


Winter moaned loudly as he humped fast and hard into his little sister’s young pussy. He could feel her heartbeat racing as their chests pressed together, matched only by his own internal percussions that were threatening to burst from his chest at any second.


Summer was lost in sensation. She didn’t know what was happening, but it was overwhelming her every sense as her brother’s little shaft probed and massaged inside her. Every nerve was on fire in the most wonderful way, then it suddenly reached the tipping point.


Both of their small bodies tensed at the same time. A sharp inhale, and then a violent tremor as they shared the most intense climax either of them had experienced in their lives. Summer felt a warm, thick fluid inside her, and that sensation made her whole body tingle with joy. She panted heavily while her brother collapsed on top of her, both of them exhausted. They were trembling from the experience, despite it only lasting for a minute.


The two siblings cuddled close together, their mingled fluids soaking the sheets, and passed out. The night was a bit chilly, but they were both sweating from the heat.