Little Big Sister

Author's Note - This story heavily delves into the realm of science fiction and excessiveness. Hyper, futanari, growth, incest, and more are all themes here. If this does not interest you please leave now.

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My name is Andrew and my life has been pretty standard, with the exception being my sister. My parents worked good jobs that kept them busy and a roof over our heads. They would spend time with me when they weren't at work and I wasn't in school. Me and my sister are twins, born on the same day but I was born first, something that peeves her as that means I get to be called the older sibling, and she defaults to the "little sister".

When our parents discovered my mom was pregnant with twins, they were ecstatic and, loving the surprise, elected to not know our sexes until birth. Doctors advised against this as they saw an abnormality in the ultrasound, and wanted them to know, but they still refused. My birth was normal, average height and weight, and no complications. But when it came time for my sister, it took much longer, and complications forced our mother to stay a few extra weeks in the hospital afterwards. I was the last to find out, in fact, I did not find out until years later.

Jamie's chromosomes show she is, in fact, female. But no one would guess just by appearances alone. She was born with a penis, and a huge one at that. In fact, it was the size and weight of a normal adult male's penis, fully grown. On a newborn's body it looked like a third leg. Doctors ran every test imaginable but they all came back with the results she was perfectly healthy. She was a completely healthy hermaphrodite, albeit a big one. The doctors told my parents they could potentially remove it as it was a possible danger to her health, but they refused and prayed for the best. They gave her the gender-neutral name of Jamie because they weren't sure what kind of life she would lead.

Of course, Jamie received most of our parent's attention after birth, as medical concerns validated such a need. I was always healthy and self-sufficient so I did not need as much supervision. After a certain incident where her appendage became exposed at school, Jamie was pulled out of school and we even moved to avoid humiliation and shame. I had to say goodbye to the friends that I had made throughout my life, but I never resented Jamie, I knew she was not at fault. Our mom quit her job so she could homeschool Jamie while I continued my regular education. After this, I never got to see my father as much because he was always working to cover our mother's income. There was never any marital strain far as I knew, and they cherished every moment they could spend together.

I graduated high school while Jamie completed her equivalency test. Afterwards I moved out of the house as I found a job with a steady income and wanted a place to call my own. Jamie still lived with our parents as they were overprotective of her, and her condition. I cannot say I blame them, but it certainly did stunt Jamie's social skills. It came as a surprise to me one day when my father called me and asked if I would watch Jamie for a weekend, as they were going on a long-overdue vacation and did not want to leave Jamie by herself. She and I never got much sibling alone time with our parents hovering over, so I jumped at the opportunity to spend some much-needed quality time with her. She got dropped off Friday morning, and our parents would return Sunday night to get her.

When she got dropped off and said goodbye to our parents and she came to hug me with surprising force, I was reminded of her abnormal physical growth. I knew little of what she had downstairs, but the rest of her stood out to any passerby. She was very short for her age, hardly 5 feet tall at age 18. She always seemed to be eating but never gained any fat, and in fact the little time I had seen her with minimal clothing, she seemed to be in fit shape, despite also not working out ever. If she was not sheltered by our parents as much, her natural beauty would certainly catch any boy she wanted. I left for work and texted her throughout the day to make sure she was fine, more than fine as I discovered, as she had been raiding my fridge and using my Xbox heavily. I came home and made dinner, we played more Xbox and I beat her every time, except the times I let her win, and we went to bed.

The next day was nothing special as I mostly did yard work while Jamie enjoyed her freedom, she was hardly allowed to leave our parent's field of vision let alone not having them around at all. That night we settled in and I threw on an R-rated movie, something I had to make Jamie promise she wouldn't tell our parents about. They treated her like she was six, even though we were the same age. I sat on one end of the couch and she sat on the other, happily eating her way through the popcorn. Reminder, it was never up to me to supervise Jamie until this weekend, so whenever a situation arose, my parents were there to bring it back to normal. That is why this caught me off guard; a particularly racy scene came on and I bit my lip hoping it would end. It dragged on for far more than a non-porno should probably allow, and I knew there was a problem when I saw Jamie was beginning to breathe heavily.

She paused the movie and looked at me with a face that had a mix of both fear and confusion. She quietly whispered:

"Andrew... no, no it's not listening please..."

She looked down at her crotch and my heart skipped a beat when I saw the tent she was erecting. I went into full panic mode as I never had to experience this with Jamie alone, and she was clearly upset and embarrassed also. She started crying softly and dropped her popcorn all over the floor. I tried to tell her it was alright but she only got more frantic.

"Stop! Stop, no! Please! Please!"

She was visibly terrified now, and unable to hold back her tears. I was almost about to reach for her when I heard the distinct sound of creaking fabric over her crying. I looked back down and about jumped out of my skin at the sight of her erection having visibly grown much bigger and was now threatening to tear through her once-loose pants. I was debating between calling my parents (and looking like the worst son ever in the process) or try again to calm Jamie down when her pants gave out. She began to cry wordlessly as I was stunned in silence in awe.

Big could hardly describe it. If my own penis (the only one I have seen in my life until now) was a lizard, hers was a dragon. I never did end up measuring it but my best guess was between 14 and 16 inches in length and nearly a foot in circumference. It pulsed wildly with every heartbeat and its veins were bulging out violently. It had a masterfully crafted curve and a head big as an apple, and purple as a plum. Jamie was obviously unable to handle the situation, tossing and turning and hiding her deep red cheeks with her hands. Her penis obviously cared little for who it was attached to and seemed to thrive on her emotions. It took multiple minutes of deep hugs and assurances to get her out of her trance. She finally pulled her hands from her face and threw them around me, bringing her pole dangerously close to myself.

She finally came to her senses and we both sat in silence for a while, her big stick hardly seeming to have changed at all, and it was most certainly not going down without a fight. I couldn't believe myself, but I had to ask Jamie how she normally gets it back to normal. She explained that she and mom would wait in the bathroom until it began to soften, which would explain a lot of times why the bathroom was occupied when the four of us still lived together. She could sense the confusion in my face and as the readers know, I expected another answer. She looked at me and asked what I was thinking about, and her pen- no, her cock, twitched. I felt downright disgusted with myself, but I also had to look out for Jamie. If she wasn't getting the release she needed, it was no wonder why she kept having episodes like this.

I told her I wanted to help her, but she must do exactly what I say and never tell Mom or Dad about this. Aside from our parents, I meant the world to her, so she agreed. I took her hand and led her to the bathroom and sat her on the closed toilet seat facing the bathtub. I was going to help her, but I also didn't know what to expect. Her member looked painfully swollen by this point, so I had to work fast otherwise this learning opportunity would be lost. I was no different than any other warm-blooded male, so I had some experience in the field of "self-help". I told Jamie once more to trust me, and she nodded. I asked her if she would feel comfortable removing the test of her clothes and she said she would, for me. She stood and slid off the remnants of her pants and took her sweat-stained shirt off, and she sat back down in her bra and underwear. I was once more stunned by two apparent abnormalities in her- her balls, which by this point in her development bigger than baseballs (and just one was definitely big enough to overflow one's hand), and the other abnormality was her stomach. I figured it would be a small, flat belly but it looked almost like an Olympic athlete's. Give it a few more years and she may have a fully defined six pack. I swallowed my pride and asked her if she knew anything about her body's development. She nodded and repeated what our mom told her: doctors noticed her abnormal muscle growth and narrowed down to the possibility that her oversized cock was feeding protein and testosterone back into her body, giving her the physique she has. It might also explain how she could eat anything she wanted and maintain her enviable figure - a lot of the energy went into fueling her cock.

I pulled a stool up next to her and sat down, and began to give her instructions. I told her to take both hands and grabbed the sides of her cock. She seemed confused at first as this was evidently the first time she has done this. I assured her I was right and she complied. She cringed as her hands made contact, they looked microscopic compared to her meatpole, both hands hardly made it halfway around its circumference. I never really had any deviant fetishes before now and I never considered myself gay, but seeing her started giving me wild ideas. She could definitely reach her own cockhead with her mouth if she wanted to, but I doubt it would fit inside. Much as I have to admit it the situation was getting me aroused, and I got hard in my pants. I wanted nothing more in that moment to take my penis out and compare it to the god among cocks that was before me now. My own cock was a normal six inches and normal circumference, but it would be absolutely destroyed in her mere presence. I am here to help her, so I continued.

I told her to move her hands up and down the shaft and mimicked the moves in the air. She nodded and began stroking her dick. It twitched hard at this, evidently unused to the attention it had been so long denied. Jamie continued to move her tiny hands up and down the shaft, taking quite a lot of travel time given its ridiculous length. She did this for a few minutes, but it only sustained her cock's rock-hard erection, without giving the reaction we want from it. I knew if I wanted this done, I had to do it myself and, much as I hated to admit it, I wanted to do it myself. I told her it may work better if I show her how it is done, and she lit up at the thought. She stood up and I sat on the closed toilet, and she sat on my lap, my legs were closed otherwise she would feel my hard as steel member. As she sat down it was obvious she weighed more than she looked, and her gigantic sack was rubbing directly against my legs. I told her once more not to worry, and I took both hands around her cock. It jumped at the feeling, and I could feel its sheer heat through my hands, almost burning me. I didn't move my hands for a minute just so I could soak the feeling in, and so Jamie could get used to the feeling of someone else touching her secret. She panted hard and looked at me, so I began to rub it. Even my larger hands couldn't meet around her thick shaft, and it still took way longer to reach either end when compared to my own penis. It was flawlessly smooth and hairless, and touching its head was like hitting a steel post. She began to pant harder and I could tell it was working. I moved one hand to her balls to speed the process up (and to sate my curiosity). They were unbelievable smooth and full, obviously stretched taut with whatever was inside them. I cupped just one of them as both would be an impossible task given their size, and she squealed with pleasure. I could tell she was close.

I moved my hand up and down her shaft faster and with a tighter grip, while giving her balls a deep squeeze. I couldn't make a dent in either, as they were both so hard and full, I was almost worried the rest of her body wouldn't have enough blood. But I was too close to stop now. She placed one hand on each of my knees to steady herself, she also knew something was coming and needed my support. I aimed her cockhead towards the tub and gave it a few more tugs and squeezes to seal the deal. She breathed in sharply and gave a loud gasp. Her balls became larger and her cock even thicker believe it or not, and she came. Hard. It didn't shoot out of her, more like it leapt out of her. It was so thick it hit the wall and stayed there, almost like a syrup. It continued to come out of her in waves, almost falling out of her cockhead because of its density and weight. Her cock surged every time a new batch was travelling through it. Her balls pulsed as they released their load, clearly a long time coming. The semen that was coming out of her was absurd, not just in volume but in density. It was more akin to honey than a normal man's watery seed. And it just kept coming.

I don't know how much time had passed when it finally stopped, a few minutes I'm sure. She fell back into me, exhausted. I leaned over her best I could and was shocked by the sight. She had nearly filled a full-sized bathtub with her semen, I couldn't even begin to guess how many gallons got pumped out of her, and it was so dense it looked less drinkable and more chewable. The scent was piercing and it stung the eyes, clearly it was overwhelming. I had never been more aroused in my life as I was in this moment. I looked back down at little Jamie and she seemed exhausted, I'm not sure if this was her first climax but it was surely the first one she had induced. I looked back into the tub once more, but I would soon regret it. The mistake I made was spreading my legs as I leaned forward, releasing my own cock upward. It landed sharp between her cheeks and my face went solid red. I tried to tuck it down before she could notice but it was too late. She sprung back to life and began talking hysterically.

"Andrew no! No! Why! No you, why!"

My fear only increased as I began frantically trying to tuck my dick back down and calming her down, and both were failing. She began crying again as the emotions got the best of her, and I think both of us were surprised at what happened next. Her own cock which had mostly deflated after he orgasm suddenly came back to life, and quickly returned to its original size. Jamie was overcome by emotions and now bawling, all of this forming a maelstrom of bad to worse. She paused momentarily and looked at her dick with fear, I did do. It suddenly lunged forward, actually growing in size before our eyes. It grew not only in length but also in girth, pushing her legs aside to make more room. When it finally came to a stop, it was truly monstrous. If it was 16 inches before, it was close to 2 feet now, and probably 18 inches in circumference. I didn't have time to take this all in before she squealed again, this time I felt something between my legs, I looked down to discover it was her balls' time to grow. They went from baseball size to about halfway to soccer ball size like over inflated balloons. She was uncontrollable by now and slid upwards towards me, which made my dick situation worse. Instead of between her cheeks, it now laid between the two orbs of her sack, their heat nearly searing my own dick which was spasming violently during all this. I did not help when I looked over her once more, and from my angle it looked as if her dick was my own. She screamed like I had never heard anything before, and she began her next orgasm.

Compared to the second orgasm, her first one looked like a leak. Her second came not in waves, but in a long, huge gush. Same density, but undeniably more volume, seemingly she couldn't pump it out fast enough. Her cockhead was so heavy by this point it weighed her dick down, so it was aimed directly into the already almost full tub. It only took her a few seconds for the frightening amount of cum to overflow the tub, as it soon needed new grounds to fill. I tried to grab her dick to aim it somewhere, anywhere- But its pure power threw my hands off and I could only watch as semen continued to fly out of her, threatening to tear her cock apart with the frightening force.

It ended, but lasted far longer than the first load. I slid out from underneath her, no longer wanting to take the risk. I found it hard to move throughout the bathroom as it was nearly up to my knees in depth, and covered most of half the bathroom walls. She quietly cried for a few more minutes before apologizing to me many times. I couldn't even begin to imagine how many dozens of gallons she pumped out. She was now stifling the last of her tears as her penis was somehow still semi-rigid. I carried her out and had her clean up in the other bathroom while I surveyed the flooded one. As I slowly removed it all I came to the realization that Jamie would continue to have problems, as this was surely a temporary fix. I needed to look out for her, and be the best big brother any way I possibly could.