Chapter Text
Sebastian swam through the water filled rooms of the Blacksight, his gills working overtime as he quickly made his way through the winding rooms, he was following a scent, a scent he needed, craved. Even in the water you simply weren’t safe from him, his colours were different, his body changing, frills softer than they were sharp, gills much more bioluminescent, glowing a soft blue. He found the end of the water filled tunnel he was tracking you down along, thinking he was having to give up swimming for a while, he quickly realizes it’s an air pocket that leads straight back down, a smug grin painting on his face after the realization. The floor was still wet, you were close.
You huffed, you’d been swimming for what felt like hours, you made it into a very large open area once again filled with water. Sighing you begin swimming, it was all open, but as you swam you realized that it felt light here, almost as if you could see the sun, it was almost all glass. You just hoped Eyefestation didn’t ruin this for you. Taking it all in, it let up and out anyway, it couldn’t hurt to take this in could it?
Sebastian however had caught up to you, and stared at you with a predatory gaze, but he wasn’t hungry, no he was curious, eagerly sending soft clicks through the water's current towards you. It made you jump, you could feel the vibrations, turning to see a large humanoid like sea creature, long tail- the more you examined the more you realized you could only assume this was Z-13, with absolutely nothing on except a scrambler in hand. You’d been told he was dangerous so your skin turns pale seeing him in front of you, watching him gently place his scrambler down. You prepare for the worst, this was his environment, you’d have no chance of out swimming him.
Sebastian's gills opened and closed softly in the flow of the water, enabling himself to calm down and calm his breathing, after all he’d worked hard to find you. He trilled, beginning to circle you. It confuses you “What…do you want?” You ask, clearly nervous. You’d been told to kill this creature on sight, but underwater you’re fully vulnerable and at his mercy. He smiles and his colours slowly change, becoming lighter, and darker again. Like a rippling wave, what was he doing, was he trying to impress you or something?
That was indeed what he was doing, slowly circling before his fins extended, making himself seem larger, like an appropriate mate. He showed off his teeth and his tail, wanting to court you. Not realizing that you didn’t have any idea what he was really doing.
He didn’t know which of the humans knew all these behavioural traits about him, and which didn’t. Not knowing Expendables were just poor subjects like him being used to benefit the hadal Blacksite. But he found a connection in watching them doing all their silly human things, due to the damage in which he sustained mentally down here, Sebastian forgot he was once human too.
He became somewhat mindless, and managed to slip by pretty easily despite his size, and swims freely, he’s incredibly powerful but doesn’t use it, because he simply forgot all the pain he was put through. He had his moments where flashes of memories would come to him in his
dreams or during the day, only worse at night. But he simply labelled them as nightmares, or better yet night terrors.
You watch him in a daze, slowly backing away, regretting it as his head turns quite quickly to face you again, tail making it easy for him to cut through the water straight to you, reminding you how powerful and dangerous he could be, if he actually wanted to. But what confused you more than anything, it’s why he didn’t want to. Or doesn’t feel he needs to.
“Please just…tell me what you want, are you going to kill me, you’re freaking me out!” You finally spit out how you felt, seeing his head tilt, eyes narrowing on one side of his face for just a moment as he taps on your gear, seeming to see his own reflection in your mask, it made him smile a little. But his eyes widened soon after, blood. Everything was covered in blood, his face was wrapped in bandages, hurt, it all hurt. You watch as his face contorts from one of pure happiness and curiosity to horror and fear.
Your heart hurts a little seeing him, this…You were told he was a monster but he isn’t, he may look like one but he doesn’t seem true, not by any means.
Sebastian blinks, he’s pulled from his thoughts from your hand on his cheek, at first his lip curls into a snarl, but he relaxes not long after, taking a breath he gently holds your hand within his own and takes in your scent further, his eyes bright blue and cold. Yet they seemed so full of warmth as he trailed a hand behind you. Slowly he starts to coil and flutter his fins at you, he’s courting you, wanting desperately for you to return something. Anything,
You sigh and swallow your embarrassment, wanting to give the guy some answer, you respond with touch, stroking over the fins either side of his head, which earns a very eager response. His head softly moving into your palms as your fingertips hook behind them and scratch back towards you, he starts purring. You could tell from how his throat jumped, like that of a crocodile, you found it endearing.
Sebastian’s soft grip at your wrist startles you from your thoughts, now concentrating back on his eyes, feeling the end of his tail begin to wrap itself around your calf, you look down to have eyes on the sensation, your eyes widening as you stare down at two uniquely shaped tips protruding from his tail “Whoa whoa I-I didn’t know I was giving you that kind of answer!” You blare out worriedly, panicking a little as you wave your hands.
Your over the top actions seemed to only make him more eager, confusing it for excitement. His mouth turns into that of a grin as he starts to trail his hands over your suit, finding a zipper and all the clasps keeping it together, easily undoing it all. He seemed to understand the tank and mask had to stay, risk you being unable to breathe, double checking by scanning your entire naked frame for gills, he knew the scientists did human experiments. Even when he forgot he himself was one too.
Your breath hitching feeling those soft surprisingly warm hands touching over your skin, he was gentle. It almost felt as if every touch he gave you was one he’d planned ahead, every touch feeling as if it had purpose. Because they did. Sebastian had his full attention on you, he wanted you to return the same, so you did, even if at first you didn’t realize it. Once your eyes locked once more, his face came closer, your heart fluttering but instead of a feeling on your lips, his head gently settled itself against yours, your foreheads touching in one of the closest, and warmest acts of love you’d ever felt. Slowly his eyelids lowered, but not fully. His eyes wanting to shut at the same time as you, you watch one another as both of your eyes close in sync, sharing every emotion in real time, slowly your mask is taken off, and his maw meets your lips. This should have been scary but it simply wasn’t, you trusted him, if he truly wanted you to drown he wouldn’t have waited this long.
Within just a few moments, the water flooded in, but it didn’t burn, or hurt like you’d expect water to feel going up your nose or mouth. Your eyes are capable of seeing in water, you could breathe. Sebastian was fast to pick up your signs of shock, his hands moving up to your neck, stroking over the slits along it. You had gills.
“They did this, to all of the expendables, without them even realizing.” Sebastian smiled “You can hear me now?” he hummed, seemingly very happy he could finally communicate with you. Watching you nod, he holds you close to him, you’re both completely nude and swimming along one another, he seems to be courting you once again.
You smile, enjoying how soft his touch felt on your skin, simply allowing him to swim with you held so close, he seems pleasantly surprised you’re so willing to do this with him. He chuckles and moves in once more “You’ve impressed me enough Sebastian~” you smile wider and hold onto his face as you slowly spin around in the water, lips catching each other in a soft kiss.
Sebastian chuckles and brings you over to the hard bullet proof glass of the wall, you were in a tube of sorts after all, he eagerly licks and nibbles at your skin, his hands spreading your legs as he gets a good look at you, his smile widening makes you blush and squeak, his eyes darting to meet yours as you see his cloaca spread. Whatever it was that pushed out was huge and it startled you, a second appendage appearing just below, “why do they look so…Different?” You ask tentatively, now getting a full look.
“Because one fills you with eggs…the other fertilizes them~” he whispers into your ear with a big smirk “And you’re going to be my incubator…I chose you.” he smiled and held your hands, spreading your arms out ever so gently as he got behind you, his ovipositor eagerly twitching between your legs, he rubbed the tip against you and huffed, unsure at first but it was exciting to have been chosen as he said, it was invigorating.
Sebastian smiled, seeing your body relax, he lined himself up, his third hand gently cupping your pussy he was soft with how he pushed through your inner walls, gentle and patient “Fuck!” you moan, clinging onto his arms, his hands encasing your smaller ones with ease as his mouth kisses your neck lovingly, purring by your ear, and along the back of your neck as he finally hilts, his tip kissing against your cervix.
You smile, feeling those big hands let yours go slack against your body, his touch returning but on your breasts this time, cupping both in one single hand, he really was huge in comparison to you. It was a pretty big turn on actually. Soon enough a new feeling arose, your head darting to watch your bulge as eggs slowly started to be deposited straight into your womb “Oh...f-fuck...holy shit.” your legs want to writhe but you quickly realize Sebastian’s tail is tightened around your legs, making it impossible to move or squirm, all you could do is allow him to rub slow circles around your clit, as his other hands held your breasts, his third guiding his eggs to sit snugly within your womb, his claws gently dragging over your belly “Sebastian!” you desperately call out his name.
“Yes?” he grins, eager to fill you full, till you popped “That’s my name, speak” he cooed, but saw you were struggling “you poor...poor thing” he moaned, biting his lip, soon moving to your shoulder and neck “Mhnf~” His teeth latching on as he gently ruts himself deeper, nudging against your cervix making you whine in pain “I have to fill you..” he spoke desperately.
“You already are..” you gasp back, holding onto him wherever and however you possibly could “Fuck..” your eyes unable to stop rolling back as more eggs slowly push their way inside, differing in size, the ones with more to them made your legs shake. Just feeling so full, for it to almost vanish, only to then build further inside you, it was driving you wild.
Sebastian seemed excited over this, holding you tight, his eggs getting slightly smaller, filling in the gaps now. “Mhn...You’re going to a perfect little incubator for me.” he growled softly “Fuck..” he purred, trilling softly towards your face as his tongue licked at your cheek, not that it did much underwater, using the long of the end of his tail to keep the two of you in a steady and soft rocking motion. “Mhn how about we get to fertilizing these eggs?~” His voice cuts through the sound of the water in your ears, and you nod eagerly.
“Please..” You smile widely and move in, begging for a kiss. He obliges, kissing you with intent as he slowly removes his Ovipositor, replacing it with his much smaller, it writhed and spiraled but it was just as long. You stare down, almost drooling, not that either of you could tell “Fuck...breed me please” the words fall naturally from your mouth as you watch in awe, moaning as he gently thrusts up into you “Fuck..feels good..” his hand still hadn’t stopped his motion on your cunt, not for a moment, you were so close.
“Such a cute pussy, mhn..your wombs holding my clutch perfectly baby..so perfect..” he moaned, it wouldn’t take much to make this big boy burst. “I hope you hold them until you birth~” he grinned, thrusting faster, hips faltering and losing pattern as he desperately chased his orgasm, and instead focused on his hand on your clit, wanting no, needing you to cum on his cock.
“Fuck! Yes please...don’t stop, so fucking close...fuck..shit...yes!” You squeal, holding onto his hand, needing him to stop rubbing as he feels your cunt clench down on him, it’s all it took to make him spill, narrowed cockhead pushing it’s way into your cervix, ensuring his cum spurted fully over his clutch. Your clutch.
Sebastian panted, keeping himself pushed as deep as he could into you, he lapped at your face, before pulling you into a deep kiss “Mhnn…hff...fhn..” He groaned as he pulled back, swimming up to an air pocket leading into what seemed to be a shop, he pulled himself away with a soft whine, his appendages retreating back into his slit “You alright?” He asks, allowing you to breathe actual air again, your gills seemingly disappearing, you’d have to get onto somebody about what the logic was there and when such a change was made, but right now your focus was on Sebastian.
“Yeah I’m good..” You smile, stroking your distended belly “Fuck..” you huff and relax “I’ll keep your clutch safe..” you smile and yawn tiredly, watching him pull himself from the water/ He truly was massive, he picked you up in his arms, shaking himself dry and helping you get comfy and warm, he kept you safe within his tail, stroking your hair, his lower hand on your belly. After all, it was his job now, he must keep his clutch warm and safe.