An Astronaut, Maybe Part Of A Team Of Researchers Working At The Very Edges Of The Space Humans Have

An astronaut, maybe part of a team of researchers working at the very edges of the space humans have explored, gets kidnapped by aliens. He's taken to some lab, experimented on, sometimes awake, sometimes unconscious, certainly never knowing what's being done to him.

Finally, though, he manages to escape, stealing an alien ship and plotting a course back to space dominated by humans. Space is large and distances are long, so even if nothing unexpected happens to slow the journey down, it'll be around nine months before he's there, give or take. He doesn't mind, though, so long as he gets back there he doesn't care how long it takes

But.. a while into the journey, he notices his belly begin to swell. Before long it's undeniable: somehow he's pregnant. With what, or how many, he doesn't know.

How does he manage the pregnancy, all alone in a stolen alien ship in the middle of wide empty space? Does it even progress the way a normal human pregnancy would, or does whatever's growing within him cause some weird (maybe horribly painful or otherwise difficult to deal with) side effects? Does he get back to other humans before he gives birth, or only after (or do others find his ship as he is in labor)?

He's terrified of what's growing inside him, not knowing what it is or how long or big its going to grow since he was unconscious for most of the experiments. He has no idea how he was implanted, so he's not even sure there's a way for whatever it is to come out. The aliens must have somehow put a synthetic womb inside him, but he doesn't know if it connects to anything, and he has no way of finding out on his tiny escape pod.

Months and months go by, and his belly swells like a balloon, quickly rounding out and bigger and tighter with each passing day. His skin is stretched taut by the halfway mark, and he's not sure how much more his tummy can take, hoping and praying it doesn't grow much bigger or he's scared he might burst. There's not much else on the ship, so all he can do to pass the time is rub his belly and feel his stretched womb undulate beneath his skin as it warps around the creatures. He's so big he can't find any comfortable position to sit or lay in, his heavy belly always pinning him down or squishing his organs in some way.

Somehow, his body manages to keep stretching as his belly continues to grow, almost in range of rescue after many painful months. He has no idea how the creatures haven't burst out and killed him by now, his belly is so huge, it looks like a grown man could fit inside his giant orb of flesh. The aliens must have done something to his body to allow it to stretch this far, because he's sure any other human body would have long since split apart under the pressure.

It's so huge he can't move anymore, not that there was much room to begin with, trapped beneath his writhing gut. It hurts so much now that he can't stop moaning and rubbing his swollen belly in pain, constantly feeling the unrelenting movements of the now massive creatures inside. They roll and kick within him, sending ripples through his tummy and making him scream and sob in agony. He begs them to stop, pleading for them to calm while he writhes beneath the monstrous swell, helpless against the unbearable pain. In pure desperation, he tries to push them out, screaming and clutching his tummy as he bares down with all his strength, but it only makes them thrash in anger. He tries and tries, delirious with pain, but nothing he does gets them to budge.

Finally, 9 months later when the pod reaches a human ship, they find him inside, sobbing weakly and begging to get them out of him. He wails and claws at his belly as they transport him to the med bay, barely able to breath under the weight. His belly his too big for him to fit into any healing pods, so he's forced to lay on a table, wheezing for breath as he's hooked up to life support. The doctors quickly set up an ultrasound to see what's inside him, smearing cold gel all over his bruised skin and pressing the wand into his flesh.

They see his womb isn't attached to anything, meaning the creatures had no way of coming out on their own, no matter how hard he tried to push. They also see that the creatures have actually become fully grown inside him. If he hadn't escaped, the aliens that implanted them would have most likely removed them in time, but without them, they had kept growing to maturity inside his womb, leaving him with a belly full of adult sized aliens inside him.

The doctors look concerned with their findings, and step out of the room to discuss, leaving him alone in the cold white room. As he lays there on the table, moaning and crying in pain and watching his undulating belly in fear, he hears the doctors outside the door say how dangerous these creatures are. They seem to be unsure of how to handle his case, figuring out what to do with him next, and his heart drops when he hears one say they may not be able to remove the creatures due to the danger they pose to the rest of the ship. With the alien modifications that allow his belly to contain the creatures, he may be forced to hold them until another solution can be found...