Izuku’s hand is small in his, but the grip is firm as he leads Kacchan down the short hall. The bathroom air is cool before the water hits, smelling of clean tile and the faint, mineral scent from the deep cedar tub. His heart hammers a frantic rhythm against his ribs. This is just like last night, he thinks, a hysterical little voice chirping in his head. When he was leading a shivering Pomeranian to the bath. Not a six-foot-tall wall of muscle and primal intent. Kacchan follows without resistance, his broad palm swallowing Izuku’s, his tail giving a single, slow wag that brushes against Izuku’s thigh.
“Okay,” Izuku mumbles, more to himself than to the man behind him. “Just… just getting clean. That’s all.” He reaches in and turns the shower on, flinching as the first cold spray hits his arm before it quickly warms. Steam begins to curl, hazing the mirror. He avoids looking at either of their reflections. “Step in here, Kacchan.”
Kacchan does, the powerful lines of his back and shoulders immediately glistening under the spray. Water sluices down the carved valleys of his spine, over the swell of his buttocks, down the thick, furred length of his tail. Izuku’s breath catches. He’s seen him, touched him in the dark, but this… this is different. The light is low but clear, honey-gold and unforgiving. This is anatomy. This is study.
“Your turn,” Kacchan says, his voice a low rumble under the water’s patter. He doesn’t turn around.
Izuku swallows and steps in behind him, the warm water a shock against his marked skin. He grabs the bar of soap, lathering it between his hands until the scent of oatmeal fills the cubicle. “I’m going to… scrub you down. Okay?”
“Yeah.”
Izuku’s soapy hands make contact with the wet, sculpted plane of Kacchan’s back, and his breath hitches. The muscle is solid, ridged under his palms, warm from the water. He works in slow, broad circles, lathering the oatmeal soap into a slick foam that reveals more than it hides—every defined trapezius, the powerful sweep of his latissimus, the deep groove of his spine. Izuku’s mind, always running, tries to categorize: supraspinatus, infraspinatus, teres major. But the clinical terms dissolve under the simple, overwhelming truth of the body under his hands. This is strength. This is the form that held him down and made him come.
“Turn around,” Izuku murmurs, his voice barely audible over the shower spray.
Kacchan obeys, a slow pivot that brings the full, daunting breadth of his chest into view. Water beads on the sharp cut of his pectorals, trails through the defined lines of his abdomen, drips from the faint, blond trail of hair leading down. Izuku’s mouth goes dry. He swallows, his own small, soft body feeling impossibly fragile in the steam. He lifts his hands again, soap-slick, and begins to wash Kacchan’s chest, his touch tentative at first, then more deliberate as he maps the territory. The firm pecs, the hard nipples, the unbelievable dip of his waist. It’s like washing a statue carved for worship.
“You’re… all muscle,” Izuku whispers, more to himself.
Kacchan’s crimson eyes watch him, half-lidded. “I’m yours.”
Izuku’s hands drift lower, over the tense, flat plane of his stomach. His gaze follows. And then he freezes. His hands stop. His breath stops.
There, at the juncture of Kacchan’s powerful thighs, is a thick, furred sheath of tawny blond, darker than the hair on his head. It’s unmistakably canine, a soft-looking pouch of skin nestled in the hard V of his hips. It’s the one part of him that doesn’t look human at all, and Izuku stares, his veterinarian’s brain clicking off, leaving only a blank, hot awe.
Kacchan makes a low sound in his chest, not quite a growl, more a hum of pleasure. “You see it.”
Izuku can only nod, his eyes fixed. As he watches, the sheath begins to shift, to subtly distend. A slick, deep red tip emerges, a blunt, swollen crown peeking from the furry hood. It pulses. Izuku’s own pussy clenches, empty and aching. He watches, mesmerized, as more of the cock emerges in a slow, inexorable slide from its hiding place. It’s thick, obscenely so, a vibrant, flushed red, and it’s slick with a clear, glistening fluid that beads at the slit. It keeps coming, revealing a pronounced, bulbous swell at the base—the knot. It’s fully out now, standing rigid and heavy against Kacchan’s stomach, throbbing with every heartbeat Izuku can see in the vein along its length.
“It… it came out,” Izuku breathes, his scientific curiosity crashing back in a wave of pure, visceral shock. “Because I was looking.”
“Mate looks,” Kacchan says, his voice rough. “Mate wants. It knows.”
Izuku’s hand, still soapy, lifts of its own volition. He doesn’t decide to do it. His fingers simply reach out, hovering an inch from the heated, alien flesh. He can feel the radiant warmth coming off it. His eyes are wide, taking in every detail: the smooth texture, the subtle curve, the way it weeps a single, clear pearl of pre-cum. He’s never seen anything so primal, so terrifyingly honest in its purpose.
“Can I…” he starts, then swallows. “Can I touch it?”
Kacchan’s tail gives a single, hard thump against the shower tile. His answer is a ragged exhale. “Yes.”
Izuku’s hand, still soapy, hovers for a second longer before he pulls it back and quickly rinses it under the spray, watching the white suds swirl down the drain. Clean. His fingers are clean and trembling as they return, making first contact with the heated, velvet-over-steel reality of Kacchan’s cock.
“Oh,” he breathes, the sound lost in the shower’s patter. His fingertips trace the thick, prominent vein along the underside, feeling the powerful throb of a pulse that matches the frantic one in his own throat. The skin is impossibly smooth, hot, and slick with more than water. Clear fluid beads steadily at the tapered tip. “It’s so… warm.”
“Mate,” Kacchan grunts, his hips giving a minute, involuntary jerk forward into the tentative touch. His tail swishes, sending droplets flying.
Izuku wraps his hand around the shaft, his fingers not meeting, and a shocked little gasp escapes him. The girth is staggering. He pumps his fist slowly, watching, mesmerized, as his movement coaxes another thick, glistening pearl of pre-cum from the slit. It swells, hangs, and then drips down the flushed red length. His mouth waters. A veterinarian’s detached analysis—canine pre-ejaculatory fluid, slightly alkaline, purpose of lubrication—dissolves into a single, primal thought: I need to taste that.
“I want…” Izuku starts, his voice husky. He doesn’t finish. He just sinks, his knees meeting the wet tile of the shower floor, the water now hitting his back and plastering his green curls to his forehead. From here, the view is even more daunting. The cock stands rigid against Kacchan’s stomach, the swollen, bulbous knot at its base a promise of impossible fullness. Izuku leans in, his nose almost touching the heated flesh. The scent is pure Kacchan—ozone, musk, clean skin, and something deeply, inherently male. It makes his pussy clench around nothing, a fresh trickle of his own arousal joining the water between his thighs.
He looks up. Kacchan is staring down at him, crimson eyes blazing, his chest rising and falling with sharp breaths. Steam wreaths his head, his dog ears twitching forward, every line of his body taut with restraint. “Do it,” he rasps.
Izuku obeys. He leans forward and licks a slow, experimental stripe from the base of the shaft all the way to the tip, collecting the salty-bitter pre-cum. The taste explodes on his tongue—musky, slightly sweet, profoundly intimate. A moan vibrates in his throat. “Kacchan…”
“More.”
Izuku opens his mouth and takes the slick, red tip inside. The texture is smooth, the heat intense. He swirls his tongue around the taper, lapping at the slit, drinking down the constant, subtle seep of fluid. His own need is a screaming, empty ache between his legs, but this… this feels like a different kind of filling. A claiming in reverse. He goes deeper, his lips stretching, a soft gag reflex hitting as the thick head nudges the back of his throat. He pulls back, panting, a string of saliva and pre-cum connecting his lips to the glistening cock.
“Good,” Kacchan growls, one broad hand coming down to cradle the back of Izuku’s head. His fingers tangle in the wet curls, not forcing, just holding. “So good.”
Encouraged, Izuku sinks down again, taking more this time. He finds a rhythm, bobbing his head, using his tongue to press along the veined underside he’d mapped with his fingers. The sounds are obscene—wet suction, choked breaths, the low, continuous rumble of approval from Kacchan’s chest. Izuku’s world narrows to heat and taste and the heavy weight on his tongue, to the fingers in his hair and the broken praises falling from above.
“My mate. Taking me so well.” Kacchan’s hips begin to move in tiny, shallow thrusts, fucking gently into the willing wet heat of Izuku’s mouth.
Izuku’s eyes water as the thick head bumps the back of his throat again, the gag reflex sharp and immediate. But a new, desperate determination surges through him, cutting through the haze of submission. More. I want all of it. He forces his muscles to relax, tilts his head back, and drives himself down, taking the shaft deeper than before, the slick, hot flesh sliding over his tongue until his nose is buried in the coarse, tawny fur at the base. The swollen knot presses against his lips, stretching them obscenely wide. He chokes, a wet, strangled sound, and tears spring to his eyes.
“Fuck,” Kacchan snarls, the word ripped from him. The hand in Izuku’s hair tightens, fingers clenching. The gentle, shallow thrusts stop. For a heartbeat, there is only the sound of the shower and Izuku’s ragged, nasal breaths around the intrusion. Then Kacchan breaks. “Mine.”
He holds Izuku’s head in place and drives his hips forward, a short, brutal thrust that shoves his cock deeper into Izuku’s throat. Izuku gags violently, his body convulsing, but he doesn’t pull away. He clutches at Kacchan’s muscular thighs, his nails digging in, anchoring himself.
“Take it,” Kacchan growls, his voice raw and ragged. He sets a punishing rhythm, fucking into the tight, wet heat of Izuku’s mouth with rough, possessive strokes. Each thrust punches a choked gag from Izuku’s throat, tears and saliva mixing on his cheeks. The musky, animal taste floods his senses, thick and primal. It’s overwhelming. It’s perfect.
Yes, Izuku thinks, the word a bright, clear point in the storm of sensation. This is what I wanted. This is him. All of him. He forces his jaw wider, tries to swallow around the invading thickness, and the broken, wet sounds he makes are pure encouragement. His own arousal is a throbbing, neglected ache between his legs, a distant counterpoint to the brutal claiming of his mouth.
“Good mate,” Kacchan rasps, his thrusts growing frantic, losing their rhythm. His other hand joins the first, cradling Izuku’s head, holding him steady for the deep, penetrating drives. “Gonna come. Gonna fill you up.”
Izuku moans around the cock, the vibration earning a sharp, animal groan from above. The knot at the base is a constant, heavy pressure against his lips, a promise of what’s to come. He can feel the tension coiling in Kacchan’s thighs, the way his whole body is tightening like a spring. The taste changes, growing sharper, more potent.
Kacchan’s hips stutter. He slams in one last time, hilting himself to the knot, and holds there. A hot, bitter flood hits the back of Izuku’s throat. He swallows convulsively, once, twice, the thick pulses endless, painting his throat with Kacchan’s claim. He drinks it down, every drop, the act itself a deeper submission than kneeling.
Finally, Kacchan stills, his body trembling with the aftershocks. He slowly pulls his spent, softening cock from Izuku’s abused mouth with a wet pop. Izuku coughing, drool and come dripping from his lips. He’s wrecked, breathless, his jaw aching.
Kacchan sinks to his knees in front of him, the steam swirling around them. His crimson eyes are dark, sated, but fiercely focused. He grips Izuku’s chin, tilting his face up. He swipes a thumb over Izuku’s swollen, wet lips, collecting the mess. “All of it?”
Izuku nods, his voice a ruined scrape. “All of it.”
“Good.” Kacchan brings his thumb to his own mouth, licking it clean, his eyes never leaving Izuku’s. Then he leans in, kissing Izuku deeply, sharing the lingering, musky taste of himself. It’s possessive, final. “My mate.”
Kacchan breaks the kiss, his breath hot against Izuku's swollen lips. "Bath now."
He rises, pulling Izuku up with him, their bodies slick and dripping. The shower spray rinses the last of the come and saliva from Izuku's chin, the water running clear between them. Kacchan turns off the tap, and sudden silence crashes in, broken only by their breathing and the drip of water from the faucet. Steam hangs thick in the small room.
Izuku’s legs feel like water. He lets Kacchan lead him by the hand to the deep cedar tub, the mineral heat rising in visible waves. The scent of hinoki wood is sharp and clean, cutting through the musk that still coats Izuku’s tongue. I swallowed him, the thought hits him, clinical and filthy all at once. His pussy gives a fresh, aching throb. I’m a pervert. A veterinarian who just deep-throated a dog cock and loved it.
Kacchan steps into the bath first, the water sloshing high against his muscular thighs. He sits, leaning back against the sloped end, and extends a hand. "Come."
Izuku takes it, his smaller hand disappearing in Kacchan's grip. He steps in, the near-scalding water a shock that makes him gasp. He sinks down, the heat seeping into his sore muscles, and lets Kacchan guide him back until he’s settled in the V of his legs, his back against that solid, wet chest. The water rises to his collarbones. Kacchan’s arms come around him, resting on the tub’s edge on either side, caging him in.
"You're shaking," Kacchan rumbles into his ear, his chin resting on Izuku's damp green curls.
"I'm not cold," Izuku whispers. It's true. He's burning up. The heat is inside and out. He can feel every inch of Kacchan against him: the hard planes of his pectorals against his shoulder blades, the ripple of his abdomen against the small of his back. And lower, beneath the opaque water, the heavy, soft weight of his spent cock resting against Izuku's tailbone. It looks human now, Izuku thinks, the veterinarian cataloguing automatically. But the sheath is still there. The mechanism is different. The knot… His inner monologue dissolves into a flush of sheer want.
Kacchan’s nose nuzzles the junction of his neck and shoulder, inhaling deeply. "Still taste me on you."
"I can taste it too," Izuku admits, his voice hushed. "In my mouth. In my throat. It's… musky. Animal." He shudders, and it's not revulsion. It's craving. "It making me wet.”
A low growl vibrates through Kacchan's chest and into Izuku's spine. One hand leaves the tub’s edge, drifting down through the water to splay possessively over Izuku’s lower belly. "Show me."
Izuku’s breath hitches. He spreads his thighs under the water, a slow, deliberate movement. He guides Kacchan’s hand lower, past the trail of freckles, until his broad fingers are cupping his pussy. It’s slick, swollen, and desperately empty. The touch is electric. "Feel," Izuku breathes, pushing his hips up into the contact. "It’s all for you. Because of you."
"Mine," Kacchan rasps, his fingers sliding through the wet folds, not entering, just petting, claiming. "All this wet. For my cock."
"Yes," Izuku gasps, his head falling back against Kacchan's shoulder. He turns his face, seeking his mouth. "Kacchan… kiss me again. Please."
Kacchan meets him halfway. This kiss is different from the one in the shower—slower, deeper, a simmering coals instead of an open flame. Izuku opens for him, and the taste is there, underneath the clean mineral water: that primal, musky signature. Izuku moans into it, chasing the flavor with his tongue. He is a pervert. He loves it. He wants to be marinated in it.
Kacchan’s hand leaves his pussy to grip his jaw, tilting his head for a better angle. The kiss deepens, turns hungry again. Izuku squirms in his lap, his ass rubbing against the softness between Kacchan’s legs, feeling it begin to stir, to thicken against him once more. The promise makes his head spin. He breaks the kiss, panting. "I can feel you… growing again."
"Mate is in heat," Kacchan says simply, his voice thick. He nips at Izuku's bottom lip. "Body knows."
Izuku twists in the water, turning to face him, sending waves sloshing over the side. The movement brings them chest to chest, the water lapping at their nipples. Izuku’s small buds are tight, pebbled peaks brushing against Kacchan’s harder ones. He looks down between their bodies, through the clear, steaming water. He watches, mesmerized, as the furry sheath at the base of Kacchan’s cock begins to distend once more, the deep red tip starting its slow, slick emergence.
"It's incredible," Izuku murmurs, all scientific awe and raw lust. His hand slips below the surface, fingers tracing the hot, firm shape as it emerges into his waiting palm. "The anatomy… the hydraulic mechanism… it's because you want me."
Kacchan’s hands find his hips under the water, gripping hard. "Fuck yes."
Izuku’s fingers tighten around the hot, slick length emerging from its sheath. He doesn’t guide it inside. Instead, he rocks his own hips forward, rubbing his swollen, dripping pussy against the firm underside of Kacchan’s cock. The friction is electric, a bright, desperate shock that makes him gasp into their kiss. He grinds down, coating the red shaft with his own wetness, the water sloshing violently around them.
“Just like this,” Izuku breathes against his mouth, his voice ragged with need. “Rub it… rub it on me. Please.”
Kacchan growls, his hips bucking up to meet the frantic slide. His hands leave Izuku’s hips to grip the edge of the tub, knuckles white, as he lets Izuku set the pace. The blunt, broad head of his cock catches on Izuku’s clit with every pass, a torturous, perfect pressure. Izuku’s thighs tremble with the effort, his small buds scraping against Kacchan’s chest.
“I want it,” Izuku pants, the words tumbling out in a rush of confession. “What you did before. On the bed. I want you to… to mark me again. All over.” He stills his hips, pressing his forehead to Kacchan’s, his eyes wide and dark with shameless want. “Piss on me, Kacchan. Cover me. I want to taste it this time.”
Kacchan’s crimson eyes blaze. A sharp, animal sound tears from his throat. “Fuck. Mine.”
That’s all the warning Izuku gets. Kacchan’s body locks, a tremor running through him from his clenched jaw to his thighs. His cock pulses violently in Izuku’s hand, and then hot come is erupting in thick, white ropes that cloud the water between them, striping Izuku’s stomach and chest. Izuku watches, mesmerized, as Kacchan’s release mixes with the bath, some clinging to his skin in viscous strands. The possessive groan that follows is pure satisfaction.
Kacchan’s hands are on him instantly, hauling him up out of the water. “Out. Now.”
Water cascades from their bodies as Kacchan steps from the tub, pulling Izuku after him onto the wet tile floor. The air is cool, raising goosebumps on Izuku’s heated skin. Kacchan doesn’t pause. He turns Izuku, pushing him down until his knees hit the hard floor, his back to the still-steaming bath.
“Open,” Kacchan commands, standing over him, his spent cock already beginning to soften but his gaze ferocious.
Izuku tilts his head back, mouth falling open obediently, his heart hammering against his ribs. He watches Kacchan’s face, the intense focus there, the flared nostrils. Kacchan’s hand wraps around the base of his cock, giving it a rough, purposeful stroke. A different stream, clear and hot, arcs through the steam-filled air.
The first splash hits Izuku’s cheek, startlingly warm. Then his collarbone. His chest. It smells musky, organic, profoundly animal. Izuku closes his eyes, letting it rain over his face, his lips, his tongue. The taste is salty, earthy, unmistakably Kacchan. He drinks it, swallowing what lands in his mouth, letting the rest run in rivulets down his neck and over his small, pebbled nipples.
“Good mate,” Kacchan rasps, his stream shifting to paint Izuku’s belly, his hips, finally aiming directly for the thatch of green curls and the slick, exposed flesh beneath. The warmth floods Izuku’s pussy, a shocking, intimate claim that makes his whole body jolt. A ragged moan escapes him, his own release cresting without a single touch, just the filthy, perfect heat of the marking. He soaks the tile beneath his knees, squirting in a helpless, silent gush, his vision whiting out at the edges.
When it ends, Izuku sags forward, catching himself on his hands, panting. He is drenched, reeking of him, utterly claimed. Kacchan sinks to his knees, frames Izuku’s face with his hands, and licks a stripe from his chin to his temple, cleaning his own scent from Izuku’s skin with a rough, possessive tongue.
“All mine,” Kacchan murmurs, the words a vibration against Izuku’s forehead. “Every part.”