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It started a couple of weeks ago, and, as with most of Knives’s self discovery, comes from observing the differences between himself and those humans. It had been a slow day on the ship and they’d just eaten dinner, the group gathering in what they called the dining room to “unwind.” There was nothing to unwind from on this lazy day, and Knives saw it for what it was; an excuse to fuck around and drink the night away.
The room was filled with casual comradery Knives had no interest in joining but was content to listen in if only for the cheerful sound of Vash’s voice. Steve was unsurprisingly sailing through a bottle of whiskey, already 3 glasses in, while Rem, Joey, and Rowan still nursed their first beers. Mary was trying to keep up with Steve in her own way, 3 beers down and working on the fourth, when their strange mating ritual began.
The conversation had steered towards fruit, Joey commenting that he’d kill for a real peach instead of the imitation dried peach cobbler bar they’d had for dessert.
“I think I miss grapes the most,” Rem chimed in. “They take too much water for them to be a viable crop for a while yet after we finally reach our new home, but the wait will be so worth it.” She had a wistful dreaminess to her tone that Vash couldn’t help imitating.
“What do they taste like?” he asked.
“They’re–”
She was immediately cut off by Steve, loudly standing from the barstool he was perched on, “I can do without grapes.” He made his way over to Mary, wrapping an arm around her shoulder.
Knives saw how precariously close to her right breast it was, knew where this was going. “‘Sides, why whine about the fruits we’re without when we got plenty of ripe peaches right on this ship with us?” He emphasized his statement by fully cupping her breast, giving it a tight squeeze that left the soft fat bulging between the empty spaces of his fingers through her loose tank top.
She bats at him without missing a beat, calling him childish and gross, but Knives doesn’t miss the small smile playing on her lips, the way her eyes intently linger on his as he pulls away. The pink flush from alcohol that was only spread across her cheeks now extends down her neck for a different reason.
Humans are so easy.
“Steve, please have some decorum,” Rowan admonishes, gaze flickering to the twins and back as if to say ‘Can’t you even control yourself in front of children, you pig?’ Knives finds himself agreeing with him, but he knows Steve is slowly starting to not see them as children anymore. Not since they’ve grown so quickly in such a short amount of time by human standards.
Another hypocritical human fault. Should a doe walk in here at this very moment and give birth, no one would bat an eye at the fawn nearly immediately standing on its own legs. But since Vash and himself so closely resemble them on the exterior, they can’t help but pass judgment on how their development should progress, even knowing that they aren’t human.
Knives looks to Vash, who seems a bit slow on the uptake with this one. He looks uncomfortable like he does when Steve is being a dick, but doesn’t look nearly as scandalized as Knives knows he would if he knew what Steve meant by ‘peaches.’
Rem tries to lead the subject back on track, clearing her throat. “Well, grapes are usually a sweet berry, with lots of juice on the inside, hence the need for all the water. Juicy like when you bite into an apple, but not crunchy like one at all. They’re soft, and can be green, red, or purple.”
Vash looks at her with rapt attention, cataloging the information like he’d be tested on it at the end of his life.
Mary leans back in her chair, “Well, I could really go for a banana. A big one.”
Eugh. Knives is easily able to school his face into one of neutral curiosity, not wanting to stir anything. The last thing he needs is the crew speaking to Steve and Mary about how the twins are catching up on these innuendos; he’s not sure how much more of Steve’s foul attitude he can endure before he snaps.
Nearly everyone else in the room, save Vash and Steve, grimaces. That actually almost makes Knives laugh.
Vash, his sweet, innocent brother, asks, “What’s a banana taste like?”
The question shouldn’t hang heavy in the air, but it does when Steve gives a loud guffaw and Mary tries to muffle a giggle behind her hand.
A beat, the other adults glaring at them, and right when Rem opens her mouth to deescalate again, Steve beats her to it.
“Check your pants, you got a little one growing in them right now I bet.”
The table erupts into an uproar, sentences mixing together, but Knives makes them all out individually. ‘Okay, that’s enough wind down time for one day,’ ‘Seriously, Steve, what is your problem?’ ‘Vash, Knives, let’s go get ready for bed, yeah?’ and laughter so high pitched it may as well be a pig squealing.
Simultaneously, Vash reached into his pockets, expecting… what, exactly? Surely he isn’t so naive that he expects Steve to have somehow extended an olive branch, secretly planting a treat in his pockets, waiting for this exact moment to come? Vash’s optimism will be his own downfall one day, he swears.
Of course they’re empty, but Knives is already leading Vash towards the door, the two spurred on by everyone else getting up to leave the room. Vash gives a disappointed look down to his empty hands, and something in Knives rages.
An image of Steve flashes into his mind, the man cowering and bloody, trapped and tied down. He’ll delight in the torture, carving into his skin for each time he made the smile on Vash’s face so much as twitch.
The image dissipates nearly as soon as it arrives, and Knives feels shocked at his own cold fire for once. These humans were making it harder and harder for Knives to justify their existence, all the ruin and depravity and deception they so easily participate in.
Knives spares a glance back into the room, and sees Mary on Steve’s lap, the two of them blushing heavily from the mix of alcohol and arousal. They aren’t fucking, not even kissing yet, but there’s something animalistic in the way the two look at each other, like they’re going to devour one another. In their eyes, Knives sees something of himself reflected back; sees the emotion he thought was reserved for his own feelings towards his brother. Something hot shoots down his spine for the first time ever, thinking of how it would be to have Vash stare back at him like that. Then, Joey’s torso steps in front of him, blocking his view as he follows up the group on their way out, and Knives turns away.
That night, as Rem sits with them for their own intimate daily unwind time, Vash asks, “What did Steve mean by me growing a banana? Is it because I’m a PLANT? Can I really do that?”
Rem sighs, ever patient with her own kind—if Knives had to choose a human to save, she’d be the only running contender. “No, sweetheart, he’s just being silly. Remember how I said humans used to make up wives' tales to pass the time?”
She looks between the both of them as they nod. “He was… well, here’s another one. There’s a fruit called watermelon, and it has big black seeds that you can’t chew. But people used to say, if you swallowed one, you’d grow a watermelon in your stomach, and you’d get big and round with it. They’re like oblong spheres, and they can grow to be this big!” She held her arms aloft, as if holding a huge ball. “Imagine if your stomach got that big!”
Vash laughed, “You wouldn’t even be able to walk!”
Rem laughed with him, and Knives gave an indulgent smile. He only allowed them with Vash, and sometimes Rem, if he were feeling generous. And then, a thought.
“Isn’t that like being pregnant?”
Rem looked at him, mild surprise quickly melting into fondness. “Always clever, Knives. It’s pretty similar, though you two already know that happens through a different means. And fortunately for us, babies don’t grow that big in your stomach. Unless you’re expecting sextuplets!” She laughed at her own joke, having to explain that humans themselves, while normally only carrying one baby, could have twins like them, or triplets, or even six at a time.
“That sounds painful.” Knives supplies.
“Oh, I’m sure it is. It’s such a rare sight though, no one really worries about that happening.” She gets up from her chair, perched in the middle of their room, and moves it back to Vash’s desk. She goes in to kiss Vash goodnight, and he wraps his arms around her neck, a hug she reciprocates. She goes to Knives next, and he doesn’t share the same enthusiasm, but she’s never seemed to mind that. She gently cards a hand through his hair, moving it from his forehead, and presses a kiss there. He simply closes his eyes and lets her.
She’s probably the only human that could ever get that close, and he’s sure she knows that, cherishes it. The sentimentalism should make him recoil, but aside from Vash, she’s the only one that shows him such open affection. He’s sure she really, truly loves him, in the flawed way humans can love anything, and so he allows it.
After she leaves, Vash ponders aloud, “I wonder what being pregnant is like. If it feels like a hug from the inside.” He turns to Knives, seems as if he wants to say something, and if Knives himself weren’t ready to drift off into sleep, he’d swear he saw that gaze, the one of the animal that lies in himself.
Surely it must also lie in Vash.
And with all the conversations of mating and pregnancy, Vash must be wondering the same thing Knives suddenly is; can Knives get pregnant?
The twins are physically identical in nearly every way, save for the opposite placement of moles on their faces and the parts between their legs. They were made in compliments to each other—Vash always giving, Knives always receiving—and it only made sense to Knives that their bodies would reflect these traits.
But then Vash smiles his sweet, sleep dopey smile, and the moment is gone, but the heat is just starting. Knives stares into Vash’s face as his brother closes his eyes, reciprocates his sleepy, “G’night, Nai,” but he’s hot, and left wanting for something. Something he’s never felt curls itself in his core, radiates heat between his legs. He’s not completely sure what to do with it, and so he drifts off to sleep, thoughts of animals and pregnancy and Vash swirling in his mind.
The next night, after Rem tucks them in, Vash falls asleep quickly in his usual fashion. Across from him, Knives finds his mind drifting again, settling a thought he’d been pushing away since the night before; himself, full and round and pregnant. Something zings down his spine and rests in his core again, and this time that warmth of his sex licks down his thighs and up to his chest. Suddenly he’s full of this energy, and he knows it won’t let him sleep it away that easily this time.
He turns to Vash, out for the count, and the heat gets worse. Knives shifts his gaze to the ceiling, creeping a hand down his legs to cup at his own sex. He jumps, the electric response shocking him, the heat somehow getting worse. He presses down at it, and his body betrays him, a quiet whine escaping his lips. He whips his head back over to Vash, but his twin is still soundly asleep, not much as a twitch coming from him. Knives’s hand seems to move on its own accord (traitor, he thinks), fingers rubbing up and down the seam of his pants as he continues to watch his brother.
It seems like vanity, to enjoy seeing his own face reflected back at him and feel so hot about it, but that still doesn’t make him look away. Vash’s face is always light, but it’s especially sweet when he’s asleep. Mouth slightly agape on breaths that could hardly count as snores, blonde hair fanned out on the pillow, body completely relaxed. He was perfect.
Whatever was at Knives’s core was coiling itself up, and he moved his hand faster. His body was drawing tight, legs starting to shake as he got closer to something. Then Vash took a deep breath, letting it go in an audible sigh, and all the tension in Knives released at once, a cry he barely managed to choke back becoming a whimper behind closed lips.
He looks back to the ceiling, all the energy gone, and he’s left drunk on the aftermath. An orgasm, he realizes. That’s what an orgasm feels like. He’d read about them in their human anatomy sex book, one that wasn’t meant for them to cover until later in their development. Knives had long read past the current unit they’re covering, Rem’s teaching too slow for his taste but seemingly fine for his brother’s (he doubts Vash needs the snail pace either, but he suspects he keeps at it simply to appease Rem). At the time it seemed purposeless for them to cover, seeing as they’re PLANTS and not humans, but it surprisingly came in handy for this situation, and Knives suspects may again in the future.
Orgasms are what humans chase when they copulate without the goal of offspring. Maybe that’s one thing they got right; Knives can see the point in it.
Throughout the next few weeks, Knives further explored himself. Not every night, but just on the nights that the heat is unbearable. Those nights typically follow Vash doing something extra sweet for him; trying to give him his portion of desert, trying to defend him against Steve’s harsh remarks, trying to drag him to the rec room when he thought Knives was too deep in his thoughts for his own good.
On those nights, Knives learned what else his body could do. It began by touching his sex directly after an over the pants orgasm. He could feel how it had started to soak through the fabric and the wetness shocked him. Self lubricating, he noted, not surprised at the fluid of his pleasure but at how much there was, how slick it was. He rubbed his hand clean on his pants and felt just a bit dirty for it. Maybe he’s a bit closer to humanity than he thought.
The next time was spent with his hand in his pants, body shivering at the contact and warmth of his own skin. That night, he found his clit; rubbed at it until he was done. The next session he drew out longer, played with it to find what made him feel the best. Tapped at it, rubbed it, circled it and oh, that one, that’s the one.
This method continued for a few nights until the ache in his core was too strong, and all he could feel was empty. It throbbed in him, begged for something to fill it, and so he found his entrance, experimentally pushing a finger inside. The feeling short circuited his brain. His finger felt how hot it was inside, how wet and tight, and his body felt how filling it was, electricity making him clench down on the digit. His palm pressed down on his clit, and he bucked into it, his orgasm coming quickly. He looked over to Vash, afraid the shifting of the bedding might have woken him, but his brother was turned away, back to him, unmoving.
From there he experimented with the combination of fingers in him and on his clit, sometimes using one finger, sometimes two, and on especially hot nights, three. He would stare at Vash, simultaneously afraid he would wake up and excitedly hoping he would.
On this particular day, as Knifes was playing piano, Vash sat on the stool, nudging him over to play with him. The slow, soft song had become fast paced and vibrant, Vash smiling at him as they created something new, together. He was the only one able to bring that out of Knives; his playfulness, his creativity, his softness. Vash’s fingers flew effortlessly across the keys, and suddenly Knives imagined if they’d be as skillful inside of him, if Vash would know the right keys to press for Knives.
The shock of heat was so strong he almost flinched with it.
He fumbled his own part of the song, fingers slipping, and Vash giggled. “You don’t lose focus a lot, Nai. Watch out, or I’ll get better than you at piano!” He grinned at him, hands never slowing even without looking down.
“Yeah, yeah,” Knives turned back to the keys, resuming their song, that face too bright to be this close.
Vash stopped playing, leaning in to stare at him. “Hey! You’re blushing! You really that embarrassed at the thought of me surpassing you at something? That means I might actually have a chance,” he laughed. Knives stayed silent, fingers slowing back to his original melody without the accompaniment, and Vash somehow got even closer. “Whoa, Nai, you okay? You’re getting even redder.”
Knives just kept playing, his face feeling like it was on fire. Vash leaned back, voice loud, “Are you getting sick!?” He made to stand, “I’ll go get Rem, she–”
“No,” Knives grabbed him, pulling him back down. “No, I’m fine. Don’t get Rem. I’m… just keep playing with me.”
Vash seemed skeptical but turned back to the piano. “Okay, but if you aren’t better by dinner, I’m definitely telling Rem.”
Their song picked back up, Knives’s face returning to his normal color with time, but the heat only turned down to a simmer. When they left, he checked the seat after him to make sure it wasn’t wet.
It was.
That night, Knives has a growing suspicion that nothing he does will cut through the throbbing pang at his core. He’s up to three fingers and thinking about adding a fourth, when Vash shifts in his own bed. Knives stills his hands, stares at the back of his head, barely breathing, heart thumping in his chest.
“Nai?”
“Y-” His voice is raspy, cracking, and he has to clear his throat, “yes?”
Vash turns around, “I can’t sleep. Can I get in the bed with you?”
A tortuous question. With Vash even closer, he’s sure he won’t be able to finish tonight, and the heat is unbearable. Being closer will definitely make it worse, too, and the energy will have nowhere to go, and he thinks he might explode with it. But Vash is his only weakness; anything in this world he asks, Knives is duty bound to fulfill. He pulls his hands from his pants, trying to quickly and discreetly wipe them on the fabric as he turns onto his side to face Vash.
“Yes. Of course.”
Vash gets up from his bed, walking the short distance to Knives’s. Knives peels back the blankets, opening his arms to his brother. Vash gets in, but only lies next to him, doesn’t wrap his whole body around Knives like he usually does when they sleep together. Knives still lies on his side, staring at the profile of Vash’s face, soft blue glow from the nightlight by the door highlighting the edges. Knives has one arm draped across his torso, and takes the initiative to snuggle closer, pulling himself flush against Vash.
“Nai, you…” he turns his head to look Knives in the eyes. “I know what you do at night.”
Oh, fuck.
“And?” Knives isn’t ashamed, he tells himself, but he can still feel the blush igniting his face.
Vash finally turns his body to him, pulls himself closer, and Knives freezes. There’s an unmistakable hardness pressing against his leg.
“And you smell really, really good when you do it.”
For a moment they stay suspended like that, staring into each other’s blue eyes, his own anxieties and eagerness and lust reflected right back at him.
He doesn’t know who moved first, but they bump their lips in a clumsy kiss, chaste and innocent as ones they’ve shared before. Vash presses even closer, bringing their bodies flush from lips to toes, mouthing at his lips like they’d seen humans do in those terrible ‘rom-com’ movies he and Rem loved so much. Knives licks back at his lips, makes him gasp and giggle, and tries lapping into his mouth. Vash breaks away on a small, breathless laugh, “It feels funny. It’s so wet.”
Knives gives him a moment to recoup, has to force himself to not simply straddle Vash and rub against him until he comes—the prize that awaits his patience will be far more rewarding than that.
Vash comes back to him, experimentally licking into Knives’s mouth, when their tongues slide against each other, slick and hot. They both whine at it, Vash instinctually slotting their legs together, hips twitching for some friction. The more they kiss, the more Knives’s pussy throbs, and he’s unable to help the canting of his pelvis, trying for more pressure from his brother’s thigh.
“Have you ever touched yourself, Vash?” Knives wants to know, needs to know if his brother had undergone a metamorphosis without him, suddenly jealous at the image of his brother touching his own cock before he could get his hands on it. Hardly fair, considering his own situation, but that’s besides the point.
“It’s gotten hard before, and I rubbed at it, but I got scared something would happen. Our biology book covered procreation, but not what happens if you do it by yourself.”
Knives is, for some reason, relieved. They’d explore his body the same way they did everything else: together.
“That’s okay, I read about it. Nothing bad will happen.” Knives kisses him again, and soon they’re both breathing heavily, hips twitching against each other’s legs.
“Nai you’re- it’s wet, on my leg.” He has the gall to blush about it, as if he hadn’t just gotten into Knives’s bed and poked him with his boner.
“Yes. Would you like to touch it?”
Vash hesitates before a meek, “Yes.”
In tandem, they pull their pants off before lying to face each other again.
“Okay. I’ll touch yours, and you’ll touch mine.”
Vash gulps, a hand tentatively rubbing at Knives’s flank, lowering to his hips. “Is this okay?”
“You haven’t even touched me yet,” Knives smiles at him.
“Right.” He looks down to his left hand, watches it reach Knives's mons and rub through the thin blonde hairs just starting to accumulate there. “Here?”
“Getting closer.” He makes it easier for his brother, bends a leg at the knee and plants his foot on the bed, spreading himself. “Lower.”
It must be quite the sight, because Vash pauses, speechless, eyes wide with wonder.
“Well. Don’t just leave me out to dry.”
Vash takes a deep breath, looks like he steels himself, and cups at Knives’s pussy. Knives jerks hard, Vash’s soft, warm hand on him new and exciting. Vash starts to pull away, already apologizing, but Knives grabs his wrist, holds him in place. “Don’t you dare stop.”
Vash massages at him, breath choked when he whispers, “It’s so wet.” Knives feels his cock twitch against him, reaches down to take it into his hand.
“You’re wet, too.” It’s already leaking pre at the tip, the length of it hard and hot in his hand. Vash lets out a sharp hiss at the sudden contact, drawing it out into a wobbly moan when Knives starts stroking him. The precum makes the glide easier, and soon the room is filled with the wet noises of eager bodies and clumsy mouths.
“Mmmph,” Vash pulls away from a sloppy kiss, hips starting to thrust, “Nai, s-somethings hap—somethings coming!”
Knives strokes him faster, kisses the worry off his lips, “Shh, let it come. Let it out for me, Vash.”
Vash’s hand on him stills, his body going rigid and still save for the small, aborted thrusts he gives, and then high pitched cry comes from him as he releases between them, cum coating Knives’s hand and thighs. Knives keeps going, until Vash’s hips slow and then jerk away, overstimulation coming fast to his inexperienced body.
Knives allows him a reprieve, eager to continue but not wanting Vash to become too overwhelmed. Vash kisses him again, tongue slow and lazy but deliberate, bereft of nervous jitters with the post orgasm haze. It feeds the fire in Knives, makes him hum softly. Vash pulls away to give him one of his signature dopey smiles.
“Nai, that was so good. I get why you do it, like, every night.”
Knives feels himself blush, “It is not every night.”
Vash giggles, “Might as well be.” He looks down to where his hand rests against Knives’s sex, brows furrowing. “Does it come out like that when you do it? It’s already so wet, I can’t imagine even more.”
“No, it’s pretty steady. Are you ready to help me finish now?”
Vash, eager as ever, nods frantically, nearly concussing them both with a hit to the forehead.
“Ouch! Yes! Yes, what do I do?”
Knives chuckles, overcome with fondness. “I want you to put your fingers in.”
“O-oh!” If Vash were eager before, he’s nearly jumping with excitement now. He sits up as Knives turns fully onto his back, spreads his legs for his brother to fully see him. Vash sits on his knees between his legs, stares at his pussy.
“This is my clit,” he circles the nub slowly. “It feels good when you rub it. But I want you to focus on this.” He spreads the lips and dips a finger into his entrance. “Start with one finger.”
Vash is on it within a second, finger circling his vagina, gathering slick, before timidly pushing in. Knives sighs, “Yeah, now gently thrust it in and out.” Vash follows his instructions, taking criticisms like don’t take it all the way out and try some different angles well. Before long, Knives doesn’t need to guide him, doesn’t even need to tell him to add another finger. Vash looks enraptured, sharp focus Knives usually only sees during unit exams and combat training.
When Vash adds a third finger, Knives lets out a soft ‘oh,’ thighs snapping closed around his arm. Vash startles, tries to pull away again, but Knives holds his hand hostage again, surprised by his own voice nearly growling, “Don’t you dare stop.”
He releases Vash to let him continue, hands gripping the sheets. Three fingers make him feel so full, he can only writhe and take what Vash gives him. He’s moaning on each exhale, and Vash shifts up, pressing his chest against Knives’s and kissing him. He can barely reciprocate, open mouth and lolling tongue being overtaken by his brother intensely probing the insides of both sets of lips.
“Vash, aah, V-Vash, Vash!” In response Vash presses his fingers up, rubs hard against his g-spot, palm rubbing up and down on his clit, and Knives cums so hard he whites out.
When he comes to, his back is arched at an angle so sharp he’s surprised it doesn’t hurt, and Vash is staring at his face with amazement.
Vash leans back on his haunches, gives Knives some room to relax. Knives sighs when he pulls his fingers out, staring at the ceiling, letting them sit in the quiet for a moment as he comes down.
The moment stretches on a bit too long, Vash normally one with a million things to say. Knives looks down to see him staring at his fingers, pulling them apart to watch a string of slick stretch between them before snapping apart, doing it again and again. He brings his hand up to his face, smells it; his eyes close, brow furrowing. He gives one a tentative lick, then quickly shoves it in his mouth, moaning around the digit. He takes the time to thoroughly clean each finger, and his face is pinched so tight Knives thinks he might cry.
“Nai, you taste so good.” Vash opens his eyes, looking at Knives like he wants to devour him. Suddenly Knives is pinned by his gaze, paralyzed.
Vash’s eyes are nearly black, pupils dilated so wide there’s only a thin ring of blue separating them from the sclera. The only thing Knives can see in his eyes is the animal.
Living on board with humans, even though he’s physically smaller, Knives has never been afraid of them. He knows he could easily overpower one if he really needed to, be it by force or psychology. But at this moment, with his twin of the same size staring at him like that, he thinks he understands what prey animals feel when they’re being hunted. He feels his heart in his throat.
“V-vash, I–ah!” His sentence is cut off by a yelp when Vash grabs his legs and pushes them up and back, spreading Knives open and nearly bending him in half. Vash wastes no time shoving his face in his pussy, tongue sloppily licking everywhere, as if he were a starved man tasting ambrosia for the first time.
Knives moves a hand down making to push Vash away—it’s too much, too soon, too intense for him to continue on—but then Vash slips his tongue inside of him, and Knives’s fingers just tangle in his soft hair, pulling him closer as his hips buck into his face. It’s hot, his body is on fire with it, with the sensation of Vash licking against his walls and the obscene, wet noises it makes.
“Vaaaaash,” he can only moan as his brother practically makes out with his cunt. He can feel the bed moving, Vash’s own hips grinding into the sheets as he breathes heavily through his nose. Vash is hard again so quickly after cumming, and it’s because of Knives; Knives’s body, Knives’s taste. The thought has the tension building in him again, and after a white out, he’s almost afraid of what will happen after this orgasm.
Vash pulls away, lifts his head to look at him.
“Nai, let me—I want to—c-can I put it in?”
Vash looks as lust drunk as Knives feels right now, and he can’t deny his brother anything, couldn’t dream of denying him this.
“Yes,” he nods.
When Vash sits up, Knives can’t help but stare at the pretty pink cock glistening with cum, straining hard against his stomach. That’s going to be in me, he thinks, and can barely contain a triumphant grin at the thought. Vash comes in close again, chest to chest, eye to eye. He drops his hips, letting his cock slide between Knives’s lips, coating himself in slick. They both moan at it; it’s hot, hard velvet against Knives, drags nicely along his clit.
Knives lets him indulge for as long as he can take; his insides are aching, and he takes the initiative to encourage him. “Vash, it’s so empty. I need you.”
“I–”
Vash barely gets out a syllable before Knives grabs his cock, aligning it with his entrance and tugging at it. The tip pressing against it makes him involuntarily clench down—he wants it too bad. Vash kisses him through it, laces their fingers together and brings their hands up to rest besides Knives’s head. He tells him to breathe and relax.
“Let me in, Nai.”
They both shudder when his cock finally pops in, and from there the glide is easy, the prep work of three fingers and an excess of slick making it smooth. Knives feels Vash inside him and it’s better than any fingers, stretches him out so well from every direction. Vash takes his time, feeding him an inch, pulling out, adding some more. Finally, with one last slow and firm thrust, two, three, Vash is fully seated.
They stare at each other, out of breath and shaking from the simple act of penetration. Vash is staring at him like an animal, and Knives knows one is shining back in his own eyes now, too.
There's no one else for him. There never was, and there never will be.
“Move.”
Knives’s simple command spurs Vash on instantly, inexperienced hips sloppy and uncoordinated, but fucking perfect. Each drag of his cock against his walls feels like lightning, and Knives is twitching with each thrust, punched out whimpers of yes and more and Vash the only coherent words to leave his lips. Vash’s mouth is open and gasping against his, still trying to lick into him, but Knives can’t even attempt to reciprocate.
“Nai, I—it’s not gonna be long this time,” he manages to grit out. Knives is close to the edge himself, can only nod, give more cries of yes in hopes that it gets the point across.
Vash speeds up, the loud slap, slap, slap of their thighs and squelching of his cunt driving him close to insanity. He must look a mess; he can feel the wet of his slick on his thighs spreading each time Vash bottoms out, making a complete mess of the both of them.
“N-nai, it’s so—you’re so tight,” he gasps. Knives isn’t sure if it’s a compliment or not, but his body still clenches down around Vash, making him whine, “Fuck!”
Knives could count on one hand the number of times Vash has ever cursed, and he’s struck with a rush of intoxication over the fact that he has the power to make him do it now. He untangles a hand to reach down to Vash’s ass, squeezing it and guiding him into an even faster pace.
With his newly freed hand, Vash puts two fingers in Knives’s mouth, pressing down on his tongue. Knives plays with them the best he can, laving them in spit before Vash pulls them out, bringing his hand down to Knive’s cunt.
Where the hell did he learn that is all Knives manages to think before Vash starts circling at his clit and all rational thought leaves him again. It feels so good, there are tears prickling in his eyes, and small sobs and hiccups accompany every other breath out.
“Nai! Nai, Nai, it’s happening, it’s coming again, Na-i.” Knives can feel him get ready to pull out, but wraps his legs around his back, locking them together to keep him in place.
“Inside, I’m ready Vash, it’s—i-inside, haaah, Vash!” Knives starts his orgasm first, but Vash is right on his heels, slamming home and grinding deep. Knives cries at the hot cum shooting inside of him, filling him even more.
Knives feels damn close to it but doesn’t white out this time, gets to watch Vash fall apart between the dark spots in his eyes as he himself does. They both shake through it, Vash’s hips jerking in halted thrusts, moans lowering to whines and whimpers as they ride it out. When they’re done, Vash’s soft cock slips out, and he sits back, blearily watching the cum leak out of Knives. He touches his entrance softly, but Knives still twitches.
“Sorry.” Vash’s voice is raspy and fucked out. “It looks good,” he smiles that dopey smile. He flops onto the bed next to Knives, giving him a full body cuddle Knives had expected at the beginning of the night, arms and legs wrapped around him, face in the crook of his neck.
They definitely need to clean up before he lets Vash fall asleep, but a few minutes won’t kill them.
Suddenly, Vash starts, raising up to lean on an arm. “Nai… do you think you’re pregnant now? What are we going to do!?”
Knives stares at him for a second, startled, before bursting into laughter. It’s a full belly laugh that leaves him shaking and gasping for breath. When he looks back to Vash, his twin has tears in his eyes.
“Oh Vash, I’m sorry.” He feels his face quickly fall from mirth to worry. “I didn’t mean to make you cry,” he wipes at the corners of his eyes. “It was a fair question, I wasn’t trying to tease you.”
Vash sniffs, “It’s not that.” He buries his face back into the juncture of Knives’s neck, hand threading in his hair. “It’s just been so long since you’ve laughed. Laughed and meant it. I think I missed it.”
A pang of… guilt? Regret? Longing? Something strikes at his heart, and he holds Vash closer.
“But if what we just did is the only thing I need to do to get you to laugh, I’ll do it every night.” Knives can hear the smile in his voice, and lets himself chuckle.
“Promise?”
“Promise. I love you, Nai.”
“I love you, Vash.”
(Knives makes them clean up before going to sleep in Vash’s clean bed. He tells Vash that they’re too young for him to get pregnant now, but they promise each other that as soon as they’re able, they’ll make their own big family, together.)