Chapter Text
Tsukishima hated the beach. He hated his weakness when it came to Yachi, the kindest one in their group, looking at him with sad, kicked puppy eyes. He hated the sun, and the salty breeze that ruined his books. He hated how loud Hinata and Kageyama were, and how Yamaguchi, the traitor, joined them in their frolicking while he was burning and bored.
His therapist’s suggestions at finding a silver lining, one thing he liked, was thrown into the sea that was currently antagonizing him. He was angry, and his hate fueled anger was the only thing keeping him moving.
He expected to be hit by a stray volleyball every once in a while, when he was in the gym . Not when he was underneath an umbrella, headache already forming from the heat. Now on top of his body being hot and sticky, every part of him hot to the touch, his face was on fire with the imprint of a volleyball.
Hinata had laughed until he caught the look on Tsukishima’s face. Yamaguchi had tried to calm him down, but he was well past that stage. He had grabbed his book, his stupid umbrella, and his towel, and stormed off.
He had half a mind to trek his way back to the public transport, and find his own way home. His anger was slowly bleeding out though and he knows that once he’s on a train in beachwear, with the cheap book he had purchased to not ruin any of his good ones as his only source of entertainment, he would regret the decision.
The beach they were at was crowded in their section, but as the clear blue water and white sand faded to rocks and jagged waves, the beach turning to more stones and shells than anything else, the crowds dropped drastically. Tsukishima trudged along, hoping the screams of the excited children at the beach(and he didn’t just mean Hinata) would fade away soon.
Sure, he would only have the trashy romance novel over here, but he would be able to sit in his silence, no bodies blocking his breeze. There’s an inlet in the distance that looks empty. He’ll move there and just keep an eye on the tide. Worst case scenario, he gets sucked underwater and never has to explain what the difference in SPF is to Kageyama again.
Slapping his towel on the sand, propping his umbrella up, he lays down. His anger drains as heat exhaustion takes over. The inlet is curved in such a way the breeze smashes the waves into the rocks, the spray misting over him and cooling him down. Book abandoned on his chest, he closes his eyes. Just for a few minutes.
Minutes turns to what has to be over an hour. The sun has shifted enough that his umbrella doesn’t completely shade him, the water somehow already creeping up to right below him on the worst of the waves. He groans, stretching. If the sun has shifted, he’s going to be burnt. His skin doesn’t feel hot, though, so he opens his eyes fully to inspect the damage.
Despite the sun clearly visible in front of him, his body is in the shade. He blinks again, all at once aware of the body beside him. He can’t say person, because blocking the sun is a massive tail, striped black and red, attached to a human torso, attached to an almost human head. The…creature, for a lack of a better word, has razor sharp teeth, claws for hands, and fins. Tsukishima feels faint as he watches the creature grin at him.
Oh. Is he hallucinating? Has the heat gotten to him? Maybe the volleyball gave him a concussion.
The creature moves and terror takes over. Except despite his usual aloofness, he is useless in such a situation. He’s frozen, every muscle in his body screaming at him to run, to get as far away from this mermaid(merman? Merperson?) as possible. Instead he lets out an embarrassing squeak, unable to move at all.
The claws of the merperson glint in the sun as he raises his hand up and—waves? What? Tsukishima’s confusion must shine through the fear because it points to itself, jabbing the claw into his bare, tanned, very nicely built chest.
‘Ku-roo,’ it says, emphasizing the Japanese slowly.
‘You talk?’ He says, his voice faint.
It points to himself, repeating what must be his name, before pointing at Tsukishima and pausing.
‘Me?’ He points to himself, more bewildered than frightened. ‘My name is Tsukishima.’
‘Tsukki!’
God, curse him. He would never be free of that nickname. ‘No. Tsukishima. -Ishima.’
Kuroo tilts his head. He points to Tsukishima. ‘Tsukki. Come.’ He points to the side, the way Tsukishima hadn’t walked over from.
He doesn’t know what possesses him to listen. Politeness ingrained in him from childhood? A weird fascination with the tail, the scales shimmering in the light? Either way, he stands, looking away as Kuroo awkwardly shuffles back into the water. He disappears underneath the waves, and Tsukishima starts, but he pops back up, waving. His jet black hair is soaked, the interesting choice of a hairstyle swept away by the water. He beckons, and Tsukishima lays his book down and follows.
Halfway there he has to abandon his shoes, waddling knee deep to follow Kuroo to what looks to be a cave, a steady stream trickling through a small passage. Tsukishima looks at the looming water, and back at the cave.
‘In here? I think we’ll be drowned out by the tide soon, I can’t breathe underwater you know?’
Kuroo says something in what must be his mother tongue, a series of clicks and shrill shrieks. He switches back mid sentence, saying only Tsukki’s name, and then back to the chattering. He swims in, leaving Tsukishima to refuse or follow.
He follows.
It’s a tight fit for how tall he is. The damp walls brush against his hair and clothes, and he thinks he scrapes his elbow but it’s too dark to really see. He follows Kuroo’s clicks, listening for his name, until finally he’s out of the passage, clamoring up onto a damp but elevated floor, watching as Kuroo swims laps around the small pool of water. He sits down slowly, dipping his feet into the water.
It’s beautiful in the cave. There are jagged cracks along the top, letting the light shine down in rays. The stone is dark gray, the small pockets of water reflecting the light back along the walls. Best of all, it’s quiet. There’s no overlap from the crowded beach that was not even a fifteen minute walk to the south of them.
He watches with mild fascination as Kuroo swims, his muscular tail beating effortlessly through the water. When he stops, it’s in front of Tsukishima, and he soaks the human as he shakes out his hair. Tsukishima shrieks, laughing at the sly look on Kuroo’s face.
‘That wasn’t very nice, you know.’
Kuroo backs up, beckoning once more. ‘Come! Swim!’
His Japanese is accented in a strange way but Tsukishima shakes his head. There was a reason he hadn’t sought relief from the heat in the water back on the beach.
‘I can’t swim,’ he admits, awkwardly, not sure if Kuroo understands him. Kuroo looks at him for a second, recognition dawning in his eyes. He opens his arms, holding them out. Tsukishima’s eyes widen. ‘No, you can’t carry me. I’m too heavy.’
Kuroo shakes his head in disagreement. ‘No. Tsukki.’
They argue for a few minutes before Tsukishima caves, lowering himself into Kuroo’s arms. He holds him tight to his torso, perfectly balancing them even with Tsukishima’s limbs flailing. He finally settles to clinging to him, koala-like. His body is solid and warm beneath him, a contrast to the chilled water. If Tsukishima wasn’t already breathing hard at the fear of absolutely nothing beneath his feet, the once inviting pool looking much scarier when he looks down into the dark black depth, Kuroo’s muscles would have him panting for another reason
He was not attracted to a merperson. No way.
Still, when Kuroo starts to move, he shrieks, holding on tighter. After a few slow laps, he begins to relax. Kuroo’s grip on him doesn’t falter for even a second. Tsukishima still holds on tight, but he nods when Kuroo starts to speed up, looking at him as he does it. The next few laps are much faster, and Tsukishima laughs as Kuroo finally slows down, swimming them back towards the edge of the pool. His back is pressed against the wall, and he goes to shift to scoot back up, but he’s stopped by Kuroo’s gaze.
There’s a trickle of the same terror as before. He’s in an unknown place, with an unknown creature, with not a single person aware of his location. All Kuroo would have to do would be to drop him, and he would sink to the bottom of the pool, drowning. He could lean in with his sharp teeth and rip his throat out. He thinks that’s what Kuroo is going to do, his gaze hungry and intense, leaning closer and closer.
He squeezes his eyes shut like a coward, not wanting to see his death, even if it’s at the teeth of a very attractive merperson. Kuroo’s breath washes over his face, warm and far too close, and then to Tsukishima’s surprise, he kisses him. His eyes fly back open, watching as Kuroo presses his lips insistently against Tsukishima’s own. He opens his mouth to protest, but with the way he’s clinging to Kuroo’s body, he isn’t surprised when Kuroo takes advantage of his open mouth to deepen the kiss.
Kuroo’s tongue licks inside of his mouth, turning whatever argument Tsukishima had into strangled moans. He tastes of fish and salt, and for a second, there’s a disconnect in Tsukishima’s mind, unable to fathom what is going on right now, and then he presses him harder into the wall, and it fades away. The front of his tail applies delicious pressure to the slowly growing hardness in Tsukishima’s swim trunks, and he feels his resistance once again fading. When Kuroo finally breaks the kiss, nuzzling along Tsukishima’s neck and shoulder, Tsukishima struggles to find words.
‘Wait,’ he pants, laying his head back on the wall behind him. ‘I can’t—I want to lay down.’
Kuroo lifts him, not flinching as he moves Tsukishima’s entire body weight up and out of the water and back to the stone floor. He hauls himself up and hovers over him, diving his face right back into Tsukishima’s neck.
‘Tsukki,’ he croons, sliding his hands up Tsukishima’s soaked shirt. They work together to pull it up and over his head, bundling it up for a very wet pillow. He licks up Tsukishima’s chest, lapping saltwater from his skin, before latching on one of Tsukishima’s pebbled nipples. He suckles and Tsukishima moans, arching his back. Tugging on Kuroo’s hair, he pulls him off of his chest and back to his mouth for a violent kiss. Their teeth clack, and Tsukishima thinks that one of Kuroo’s many fangs slices a small cut into Tsukishima’s lip. He rocks his hips at the sting of pain, moaning.
‘Kuroo,’ he gasps, feeling along the rippling muscles on Kuroo’s shoulder blades. His eyes flutter closed once more, letting himself sink into the sensation as Kuroo kisses down his jaw, licking around his collarbone until the pleasure is replaced with a sharp, intense pain. He cries out, his fingers digging for purchase into Kuroo’s back as he looks for the source of the pain. Kuroo looks at him, teeth still embedded into his shoulder, before biting down harder.
Tsukishima shouts again. He’s torn in two: one side screaming out in pain, scared that Kuroo truly means to eat him to death, and the other side in ecstasy, his cock kicking in his shorts as he cums, the wet spot indistinguishable from the water. Once the high from the orgasm begins to subside, the reality of the situation begins to sink in. Kuroo hasn’t bitten any harder, but he hasn’t retreated. The pain begins to radiate from his shoulder, the salty sting of ocean water dripping into the wound off of Kuroo’s face.
He realizes belatedly that he’s crying, vision blurring from where he was trying to hold Kuroo’s gaze. Kuroo croons at him again, reaching up to pat him on the head. He can’t tell if it’s condescending or comforting. He wants to make a joke about not playing with his food, but a choked sob comes out instead.
‘Don’t kill me. Please, Kuroo.’
He holds him still for a few more minutes, the pain slowly being replaced with a warm, fuzzy feeling. Are merfolk venomous? Will he have to watch as Kuroo devours him, piece by piece until the blood loss or shock finally does him in?
Kuroo finally unlocks his jaw, pulling back with Tsukishima’s blood dripping out of his mouth. He looks to the side at the marred flesh of his shoulder, another choked sob coming out. He already feels lightheaded, but Kuroo slides his clawed hand carefully under his head to lift it up. He bites at the air a few times, miming what he supposedly wants Tsukishima to do. It’s hard to tell when all he can focus on is the pieces of what looks like his skin in Kuroo’s teeth. Kuroo presses Tsukishima’s head against his own shoulder, waiting.
Deliriously, panicking on if this was about to turn him into a mermaid like in the old vampire tales, he bites down. Hard. His teeth are blunt, and Kuroo’s skin doesn’t give at first. He summons up what remaining strength he has to clamp his mouth down harder, flesh giving way to a gush of blood, a pleased hum coming from Kuroo. When Kuroo lets him stop biting, he has to lay Tsukishima’s head down. There are black spots floating in Tsukishima’s eyes, and the last thing he sees before passing out is Kuroo picking his flesh out of his teeth with his claw.
His dreams are vivid. Kuroo takes his time, taking chunk after chunk of Tsukishima’s body into his own, swallowing him down piece by piece, while he watches with no desire to stop him. He does the same, the two of them slowly morphing to one being. His blood races, his heart bursting with fear, joy, love, complete devotion.
When he comes to, his dreams fading into the forgotten, his body burns. If Kuroo hasn’t finished him off, he would bet that his shoulder was infected. He reaches up to touch it, unable to bear looking at it, but his hand is slapped away.
Don’t touch.
He starts, Kuroo’s voice clear in his head. In his head. Not out loud. He forces his eyes open to see Kuroo wrapping his shoulder in seaweed, Tsukishima’s bite mark disappearing. One look at his own shoulder reveals a similar wrapping. He whines, wanting the unfamiliar bandages off of him, but his hand is once again stopped, the fin of Kuroo’s tail smacking it down.
He shifts, wanting to sit up, but his body gives out, the cave spinning. Why is he so hot? His skin is sensitive to the touch, burning trails left where Kuroo brushes against him. He opens his mouth, whimpers coming out in place of words.
‘What…what did you do to me?’
I bit you. You bit me. We’re bonded now. Mates.
‘Why are you in my head? Why am I so hot? Kuroo,’ he cries.
Kuroo chatters at him again, scooting closer to him. Tsukishima wants to roll away in fright. He wants to roll closer. He settles for not moving.
It’s easier. Your language is hard, but you can understand me this way. You’re going into heat.
‘I’m what?’ He says, panting. His body feels weird. There’s a steady thrum of arousal lacing itself around the warmth.
Heat. It will prepare you to take my pearls. I need a good mate to hold them for me. You’re beautiful, Tsukki. You’ll make them beautiful.
He whines. At Kuroo’s words, he noticed how empty he felt. He could carry a few pearls, that was probably fine. Anything to fill what felt like a gaping hole inside of him. He nods, agreeing just to agree. He realizes belatedly that his swim trunks had been removed, hanging from the rock furthest away from the pool of water they had been in. He would be disgruntled if he wasn’t aching for Kuroo’s touch.
‘How ah—‘ he whines as Kuroo moves back between his legs, his tail rubbing against the inside of Tsukishima’s thighs. ‘How does this even work? Do you even have a dick?’
Kuroo clicks his teeth together. He grabs Tsukishima’s hand, pulling and pressing it against his tail. The scales are warm, firm and solid, until Tsukishima’s fingers dip between two scales, slipping into Kuroo’s body with ease. He gasps, his stomach curling at the heat surrounding his fingers.
Coax it out, I’ll open you up for it.
Even heat drunk, his mind addled from the venom in Kuroo’s bite, he thinks of Kuroo’s claws tearing apart his insides. He groans, shaking his head. He’ll do both.
‘I don’t suppose you have any lube?’
My bite will help you. You don’t need it.
Tsukishima lifts his legs up, allowing Kuroo to hold them up towards his head, and finds that his words ring true. He circles a finger around his shockingly wet rim, pressing it inside with no resistance. He moans at the feeling, shivering as it only ignites his desperate desire to be full even faster.
It’s surreal again. His body feels like he’s floating, he’s got three fingers in his ass with no external lube at all, and he’s got three fingers on his other hand inside Kuroo’s slit, prodding around like a virgin. Kuroo’s trilling at his ministrations, mouthing along Tsukishima’s neck until finally, Tsukishima’s fingers get pushed out of him by Kuroo’s dick.
He watches as his cock springs free, full and dripping with whatever slick was inside of Kuroo. It’s not human-like, which shouldn’t surprise him. It’s red like the stripes on his tail, a mix between a tentacle and a tongue, and almost absurdly long. Tsukishima wants to choke on it; he can feel his mouth water at the idea.
Next time, Kuroo tells him mentally, confirming that the mind speaking goes both ways. My pretty human, you will get your fill next time. Now, let me complete the mating. Then you will truly be mine.
‘Oh god yes,’ he chants, sliding his fingers out so he can hold up his own legs. ‘Fuck me. Fuck me.’
The tip of Kuroo’s cock(appendage?) presses against him, easing its way inside of his body. He shudders, his eyes rolling back as the primal urge that had been filling him was sated, however momentarily, by the stretch. The pleasant ache crests, quickly turning to mind numbing overstimulation as it just doesn’t stop. It’s wet all over, like he had coated himself with lube, and sticky inside of Tsukishima, reaching areas no one had reached before.
Tsukishima’s mouth is open, harsh pants and moans being the only thing he’s able to get out. He thinks briefly about how deep Kuroo was inside of him, still pushing in further with each roll of his hips. If he had been born with a cervix, he could already picture Kuroo’s cock pushing into it, depositing his pearls, his eggs, whatever he would give Tsukishima directly into his womb.
Unannounced, his orgasm crashes into him once again at the thought, his cock spurting up his stomach, untouched. Kuroo groans, licking the uninjured side of Tsukishima’s shoulder and finally bottoming out. He holds Tsukishima’s hips flush against him, panting against Tsukishima’s skin. He isn’t moving, but the tentacle-like cock writhes inside of Tsukishima.
I could give you a womb, Kuroo says to him, pulling back with his fangs bared. A few more bites and I can give you anything you desire. You can carry my pearls like this though.
Tsukishima’s mind races with the thought. He would never have imagined even 6 hours ago wanting it, wanting to be a broodmare for a merfolk, but part of him does. The urge to be filled now without waiting overtakes that desire.
‘Don’t wanna wait, give me them now. Please.’
Kuroo chatters appreciatively, rocking his hips once more. Every thrust is accompanied by his cock twisting and turning inside of Tsukishima, driving him absolutely mad. He’s never been fucked so good in his life. He’ll never be fucked like this by anyone else, even if he let them try.
The stone floor of the cave is cold and rough on his back, and his wet t-shirt does little to cushion his head as Kuroo fucks him savagely, pistoning himself in and out of Tsukishima’s body. He has no grip on the wet stones so he simply throws his arms around Kuroo and holds on, grabbing his hair and his back and anything he can to ground himself while Kuroo uses his body.
He can feel it inside of him. There are tiny lumps of pressure starting at the base of Kuroo’s tentacle, traveling towards the tip. Almost reflexively, he starts to chant yes, each pearl giving him bursts of pleasure as they’re laid inside of him. Kuroo’s mouth smothers his own as he growls, his hands trembling, claws pricking Tsukishima’s waist.
Tsukishima doesn’t know if it’s his imagination, but when Kuroo licks the inside of his mouth, he leaves trails of spit tinged with Tsukishima’s blood from earlier. He moans, chasing the taste when Kuroo pulls back.
Good, perfect Tsukki, so good. One more bite, yes?
‘Yes,’ he agrees, not sure what he’s agreeing to until Kuroo’s teeth are back inside of his flesh, sinking into the other shoulder. Pain and pleasure and ecstasy wash over him, his entire body twitching.
Mine , Kuroo chants, smearing his face with blood as he licks around the new wound. You’ll come with me now.
The pain provides some clarity. Yamaguchi and Yachi are definitely looking for him by now. They would never find him in the cave, and if he goes with Kuroo, they’ll never know what happened to him. He has a life outside of this, he can’t just abandon it.
‘Kuroo,’ he cries, his body shaking as they both come down. ‘My friends. They’ll look for me. I can’t—‘
Shh, sweet Kei. They can’t take you from me. You’ll keep my pearls safe, make them glow like the moon, then we’ll see.
Tsukishima’s gasps for air after his climaxes haven't calmed down. In fact, he realizes with growing horror that they’re getting worse. He can’t catch a breath. His neck burns, and the world around him begins to flicker in and out. He can’t breathe.
He tries to shout, but with no air, the noise he lets out is pathetic. Kuroo’s eyes gleam as he hears it. He slides backwards, holding Tsukishima to him. Tsukishima’s scrambling, trying to reach his neck to determine what’s going on, but Kuroo holds him fast. The water splashes as Kuroo’s tail hits it first, and Tsukishima thinks this is finally it.
The third time's the charm. Kuroo really means to kill him now, to drown him under the sea, use his body to keep the pearls safe. He clamps his mouth shut as his head is pulled under, his eyes squeezed tightly closed. He’ll never see Yamaguchi again. He’ll never conspire with Yachi to trick Hinata into quitting practice, or hit one of Kageyama’s tosses again.
Breathe. Open your eyes, my Tsukki.
The saltwater stings, and his glasses are abandoned above, but slowly the blurs around him begin to take shape. He breathes in, feeling his neck flutter around the water. Kuroo’s body supports him still as they continue to sink down.
Gills. He has gills on his neck. He opens his mouth to talk, only for nothing to come out under the water.
Like this, Kuroo reminds him. One week. Then maybe I’ll let you go ashore again.
The headlines in the paper range from accusations to dismissals. A quarter of Japan thinks that Tsukishima Kei went on a drunken bender and was lost in a drug fueled haze for a week. A quarter believes he was abducted by someone. Or something. Aliens, creeps, monsters of all shapes and sizes. The rest of the country didn’t care who he was or where he was.
No one knows the truth, Tsukishima thinks, staring outside of Yamaguchi’s window in the direction of the beach. He hadn’t told his friends what had happened. He didn’t tell the authorities or his family either. He couldn’t remember, he lied. He had walked away for peace and quiet, and the next thing he knew it was a week later and he was found sitting on the beach, wearing the same clothes.
No one knew of his week underwater, letting Kuroo claim his body again and again. He could feel the phantom weights of the pearls inside of him, and if he closed his eyes, he could remember how Kuroo had coaxed them out of him while he cried in pleasure.
He traces the bite mark unconsciously under his shirt, wondering what Kuroo was doing now. Hinata barges into the room, talking a mile a minute and pulling his attention away from the window. Pulling his attention away from his plan on how to get back to Kuroo.