System-Y

Content Warning: muscle expansion/growth, excessive masturbation, giant dick and balls, breeding kink, oviposition, egg laying via dick, sounding, alien parasite, sex obsessed, voyeurism, mpreg

"Dax! There you are, dude, finally!"

Fresh off his security detail, Dax turned when his friend Fletch called out to him in the locker room. "Hey, man, long time no--" he began as he turned to look at the other man and stopped short, jaw all but dropping at the sight that met his eyes.

He and Fletch had been born and raised in the same colony on Mars so while they hadn't actually known each other as kids, their shared hometown had given them something to bond over when they'd both wound up assigned to the same platoon two years ago. They'd become fast friends since though hadn't seen each other in over a week since being assigned to opposite shifts after arriving on Watch Station-416. After months on the front lines of what the feeds had started calling 'the galactic civil war' the news they were being rotated to a low-risk region well within Alliance borders had been welcome.

Everyone in their platoon was more than ready for a little boredom.

Everyone except Fletch, apparently-- he looked like he'd somehow managed to squeeze six months of heavy lifting at the gym into a single week.

"Holy fuck, Fletch, the hell you been doing? Did you move into the gym full time or something?" Dax demanded incredulously and grabbed his friend's bicep. It was rock hard when he flexed it and way bigger than it'd been the last time they'd seen each other in the mess hall.

The other marine laughed as he opened his locker and stripped off his shirt to get dressed for his shift. Dax couldn't help but stare-- his friend was absolutely shredded. They had both been plenty muscular the week before-- the peak of health and fitness per standard marine regulations, but this was a whole other level of bulk. So much so he couldn't help but think the other man even looked taller, though he wrote that off as just his imagination.

"Not exactly," Fletch replied evasively. When Dax kept staring at him expectantly, though, he relented and waved his friend in closer to speak in a voice just above a whisper so the rest of the marines in the locker room wouldn't overhear. "I found this new bit of hardware at a shop down on deck thirteen-- been using it all week and its done wonders."

Dax let his eyes rove over Fletch's rippling pecs, thick forearms, and narrow waist. "No shit. What shop? I have got to get me some of that," Dax pleaded. Deck thirteen housed the docks for civilian merchant ships so a lot of shops had cropped up there to avoid the additional taxes that came from selling on the upper decks where they did actual quality control and import inspections. He hadn't been himself yet, but he'd heard you could find all sorts of fascinating, questionably legal stuff there if you knew where to look and who to ask.

Leave it to Fletch to figure that out within a few days of arriving on station.

For a moment Fletch hesitated, almost seemed like he wasn't going to answer Dax, then seemed to change his mind. "Little shop way back in the north-west corner of deck thirteen; wedged between an after-market wetware clinic and a junk shop-- you'll know it when you see it. Just ask for a 'System-X'." He straightened then, and in a normal voice, said, "Its your turn to take leave for the next week, right? Have fun!"

~~~

The shop, unlabeled like most of the places in this section of deck thirteen, was tucked away in a particularly quiet corner where no one made eye contact or pretended to notice anyone else they happened to pass in the narrow alley. Determined not to stand out Dax did the same and entered the cramped, tiny shop to address the nondescript woman stationed behind the counter.

"Hey, I'm looking for, uh...for a System-X?" Dax asked, voice low as he leaned against the counter.

"Oh," the woman said, plainly surprised, even perturbed by the request. She glanced up at what Dax realized was a security camera in one corner and said, "I wasn't told we were giv-- selling anymore of those. Where did you--"

Just as Dax was beginning to suspect Fletch had walked him into a heap of trouble the woman paused, head cocked slightly to one side as if listening to something he couldn't hear-- entirely possible considering how discreet earphones were these days.

"Actually," she said and smiled, "we're out of the System-X but we do have a System-Y available!" Seeing the doubt on his face, she pressed, "Oh don't worry, it's the same thing, just a newer model! If you don't like it, bring it back within seventy-two hours for a full refund-- no questions asked!"

That should have been the moment he knew the offer was too good to be true, but blinded by the low price she quoted him and the memory of Fletch's impossibly bulked out physique Dax caved and immediately bought it.

"So, how do I use it," he asked when she passed him an unlabeled box across the counter.

"Oh, directions are inside! Feel free to come back by if you have any questions, though," she said with a wink then proceeded to shoo him out of her shop and close up after him.

A little nonplussed by the whole affair, Dax went back to his quarters (the backwater space station was spacious enough that even rank-and-file like him got their own room for a change) and locked the door behind him before he tore into the box, eager to finally discover what all the fuss was about.

Inside was a canister about sixteen inches long, about the size of his forearm, and he didn't have to look at the instruction card in the box to figure out that 'System-Y' was a flesh-light.

"Fletch, you asshole," Dax complained aloud with a groan of frustration. If his friend hadn't wanted to share the secret to his sudden gains he could have just said so instead of sending him on a wild goose chase for a goddamn pocket pussy of all things.

Annoyed and already plotting revenge, Dax tossed the flesh-light onto his bed and went out get himself some dinner. By the time he returned an hour later his ire had faded enough to allow curiosity to take over so he took up the thing and inspected it. The design was exceedingly simple-- a basic cylinder with some grooves to make grasping it easier as well as a screw on cap to cover its mouth when not in use. Unlike standard offerings of the same type of device, this one had no labels on it at all-- not even a brand name.

More curious than ever at this strange state of affairs, Dax unscrewed the cap and watched as the material within expanded outward by several inches to simulate a particularly plush set of labia, though only the large outer lips-- beyond those was a wet, fleshy hole. Dax pushed two fingers inside and was shocked to find it didn't just feel slick and warm (standard offerings for such a device these days)-- it felt alive.

Startled by the thought, the marine dragged his fingers back out again and immediately picked up the instruction card that had come in the box. Said 'instructions' were simple enough and boiled down to 'insert dick, fuck to completion', as one would expect, though on the back of the card he did find more information about the materials involved.

"Syn-flesh," he murmured aloud as he read. He'd heard of it before-- mostly you saw it used in medical procedures where you needed to regrow a lot of muscle or other tissues after a traumatic injury. More than a few people in his unit had skin or muscle that had been custom printed for them in a med-lab to replace what had been lost.

Dax wasn't entirely sure how he felt about using living tissue as a fuck toy-- even if it wasn't attached to a larger organism or capable of feeling pain, but there was no denying that the toy itself felt amazing...

"Fuck it, why not?" Dax mused after a moment's consideration and dropped onto his bed. His new purchase wasn't about to get him as jacked as Fletch but having a new toy to jack off with over his week of leave wasn't bad either.

It was, in fact, amazing.

Dax barely managed to last more than a minute after pulling his dick out of his pants and slipping it into the mouth of the flesh-light before he was pumping a load into the thing.

"Ooooh fuuUUUuuck," he groaned loudly, hips jerking unsteadily as he stroked himself with his new favorite toy. He'd never felt anything quite like it-- it was more than just a pussy, it was pleasure incarnate wrapped flush around his cock, spasming and flexing along his length in a perfect counter-tempo to the speed of his thrusts.

It was the perfect temperature too, and slick enough that he could continue to thrust into it even when it had him gripped like a vice.

"The fuck is this thing?!" Dax moaned as he caught his breath and pulled it free of his cock with an audible slurp. He looked at the card again but the only thing he learned was that if the outer plastic casing broke the sleeve itself could still be used so long as you kept it in water between uses.

Eager for more and already hard with anticipation, Dax stripped out of his clothes and settled in for another go, determined to last longer now that he knew what to expect. The marine tried to keep a slow pace at first but it wasn't long before he was jerking himself off with the thing just as fast as his arm could pump, hyper-focused on the sweet, hypnotic slide of the synthetic pussy up and down the length of his cock.

"Yes! Oh god, yes," he whimpered, body coated in a fine sheen of sweat. "Gonna fuck you so good," he panted, mouth hanging open, tongue lolling as he lost himself to pleasure. This time, though, just as he reached the brink of orgasm, something inside the sleeve pressed into his urethra and slid down into his shaft, making his eyes fly wide open as he gasped and twitched his way through an orgasm even stronger than the last. Whatever it was inside of him was strong enough to forge a path halfway down the length of his dick, but supple enough that it bent with him to prevent injury. "Fuck! FUCK!" he screamed as the hole he was fucking fucked his hole in turn and siphoned off his seed while his body attempted to ejaculate.

The person in the next room over banged on the wall but Dax didn't pay it any mind as he lay on his bed covered in sweat, trembling, head spinning in the wake of his orgasm.

After laying there on his back with his dick still trapped in the flesh-light Dax pulled it free again, moaning pathetically at the twin sensation of pulling out while it pulled out of him.

"Seriously, what the fuck," he panted incredulously and took a closer look at the strange flesh-light. He stuck a finger inside again and jerked it back out again when he felt something coil around the digit. A thin, fleshy tendril of some sort came with it, prodding blindly at the tip of his finger as if in search of something, and Dax realized this was what had been sounding him. "What, you want more already?" he asked absently, squeezing it gently between his fingertips when it began to retract back inside the sleeve.

Pleased to find the toy came with a self-cleaning function Dax cleaned himself up and went to bed after that, resolving to wake up at a reasonable hour the next morning to get a few errands done.

The marine dozed for awhile, but tossed and turned well past midnight when he woke fully to stare at the ceiling for awhile until he broke down and reached for the flesh-light.

"One more won't hurt," he mumbled, cock already stirring in anticipation. He'd sleep better if he got off again-- he always did.

Wanting to save his arms, Dax bundled up his pillows and wedged the flesh-light into them so he could effectively fuck it doggy style with the pillows serving as leverage.

"Hnnngh, yeah," he moaned as he slid inside, eyes fluttering shut as a gentle, mind-numbing bliss settled over him like a weighted blanket when the sleeve enveloped him in a welcome embrace. "That's it..."

He set a slow pace at first, pulling his hips back until the tip of his cock just kissed the sleeve's plush, slippery outer lips, before pushing gradually back inside. He relished every inch, the way the syn-flesh molded itself perfectly to him every time so it was a tight fit without being too tight-- like a wet, cock-starved virgin lay splay-legged and desperate beneath him just begging for it.

The tentacle penetrated him again, drawing a low bestial groan from the marine and driving him to thrust faster in an attempt to force it deeper inside of him. It probed and writhed along the inside of his shaft with a mind of its own until Dax was panting and humping his pile of pillows like a dog-- all thoughts of getting off quickly so he could go to sleep forgotten.

It reached the base of his shaft and kept going-- the feeling one he couldn't quite put words to. The sensation of something penetrating all the way down into his balls was simply indescribable.

"Fuck-fuck-fuck-fuck-FUCK," he panted into the velvet dark of his quarters in time to his thrusts, bed rocking roughly under the force of his enthusiasm. He'd never had sex with a partner feel as good as what he was getting from the System-Y and when it sucked his cock and pushed deeper into his balls at the same time as he came a moment later he knew he'd probably never be able to go back.

His balls seized when the marine came and the sensation of them going taut around the tentacle that had forced its way into them to feast on his seed at the source made his orgasm feel like it lasted a lifetime. The grunts and groans of a desperate animal were all the noise he could make through it all until, finally, he flopped bonelessly sideways onto his bed, trembling from the exertion and the pleasure.

The tentacle pulled free after a minute and the sensation of it being dragged out of him made the marine swear and shake and nearly come again. When it finished, he pulled the sleeve away and rolled onto his back to examine himself after clicking on the bedside lamp. His cock was swollen and red, like he'd been using a pump, and while it was difficult to look at them, his balls felt...swollen-- as if they'd been filled with something rather than been emptied.

They felt good-- hot and heavy in his hand. So did his cock, which was still semi-hard and getting harder by the moment.

"One more won't hurt," he repeated himself groggily without even realizing it.

~~~

Sleep didn't claim for an hour or more after that and if he was being honest he didn't actually remember making the active decision to go to sleep. When he woke, he was sprawled naked on his bed, flesh-light on the side-table, and he grabbed it without a second thought the moment his bleary eyes landed on it. The insistent, pleasurable ache of severe morning wood was immediately soothed by the sleeve's warm, supple embrace and Dax was jerking himself off before he'd even woken up enough to register the time.

He came quick and hard with a low, shuddering groan, bare body threatening to break out in a fresh sweat as the System-Y drank deep of his seed. It didn't even have time to penetrate him in turn he finished so quickly.

The sleeve was blessedly self cleaning, but the same couldn't be said for Dax so the man rolled out of bed and went to take a shower, bringing his new toy along without even thinking about it. The heady rush of the hot water over his body while he fucked the flesh-light was a new kind of ecstasy that lead to him linger under it's spray unleashing load after load as his cries of pleasure echoed in the tiled room, filling his ears with a cacophony of his own gratification until the water ran cold.

Only then did he register just how hungry he was -- chill water granting him enough clarity of mind to feel a modicum of shame at how much time he'd wasted masturbating like the galaxy's horniest teenager.

Dax dried off and put the System-Y aside then turned his attention to his pressing hunger. The quarters he'd been granted were made up of a mid-sized room with a bed, small sofa, kitchenette, and on suite bathroom-- an extravagant luxury after months on the front-line sleeping in a bunkhouse. Happy to cook after so long on rations, Dax threw a few things together he'd bought the day before in preparation for his leave, then sat down to eat on the sofa while he watched some TV.

The programming didn't do much to hold his attention, though, and soon the marine found himself idly playing with the flesh-light in one hand while he ate with the other. Then, caving into his most hedonistic impulse yet, he dragged down his sweatpants and slid the sleeve home onto his still-restless cock-- just to keep it warm while he finished eating.

Once it was on, though, the sleeve's fleshy interior began to stroke him off of its own accord, as if just as impatient as he was. Dax moaned around a mouthful of food and swallowed hurriedly.

"Fuck, oh fuck," he muttered and forced himself to quickly demolish the rest of his meal before he rolled over, pushed the flesh-light down between the cushions of the couch back, and proceeded to fuck it with wild abandon. Anyone who had walked in unannounced then would have been treated to a view of the marine gripping tight at the couch's frame as he fucked the pillows like a dog, mouth hanging open and tongue lolling to complete the picture.

Completely eaten up by lust, Dax couldn't even hear the TV anymore as he panted and fucked the System-Y, let alone remember the plan's he'd made to leave his quarters to run errands. He found his way back out of his clothes and soon all the work of his shower was undone as the marine soon became soaked in sweat once more as he pounded the sofa, its cheap metal frame beginning to rattle and groan under the onslaught.

"Take it," Dax grunted, every muscle tensed and working as he chased his release. "Take it-- take my cock!"

He came again with a shout and inside it's hard plastic case, the System-Y squirmed and milked him for every ounce of semen it could wring from his increasingly swollen balls.

~~~

Dax lost all sense of time after that, as well as the number of times he'd orgasmed, but on day three he came back to himself enough to register his own reflection in the mirror when he passed it on the way to masturbate in the shower again. Ironically he'd been showering a lot more than usual, once every few hours, but not because he took any notice of how sweaty he'd gotten-- it just felt that good.

The man that caught his eye in the mirror made even Dax's lust addled mind pause and delay its next round of sexual gratification long enough to take a good look at himself.

He looked like Fletch.

Not literally, of course, but his body had gone through the same extreme changes. Dax was more muscular than he'd ever been in his life and he was pretty sure he was at least a couple of inches taller. His dick, too, he realized as he ran his hands down his chiseled abdomen to its base, was significantly bigger in both length and girth. He'd been pretty big in that department to start with but now he looked like one of those holo-porn star studs with augmented dicks that pushed the limits of what a standard human hole could reasonably take.

"Holy fuck," he groaned, half-hard cock swelling further, stiffening to stand straight out before him with a vigor and strength you could have hung a weight from.

Fletch, it seemed, hadn't been yanking his chain after all.

Dax grabbed his massive pecs and squeezed, marveling at their size and the heightened sensitivity of his big, pert nipples. Those had grown significantly in size from how they'd been a few days before-- more than his pecs or even his dick. The dark areolas were puffy and the tips thick and stiff; just begging to be sucked.