The water in the jacuzzi tub is a deep, steady heat, the jets a low thrum against their skin. Izuku floats back against his father’s chest, the snow outside the bathroom window falling in silent, fat flakes through the darkness. Tiny, warm white lights are strung along the wooden beams above, their reflection shimmering on the water’s surface. Katsuki’s arms are loose around him, one hand idly stroking his damp stomach.

Izuku’s own fingers drift lower, pressing gently into the soft swell of his lower belly. It’s still there, a slight, tender fullness that hasn’t subsided since yesterday. Since the bed, the table, the window, the floor. He can feel the ghost of every thrust, the phantom ache of being stretched and filled, over and over. His skin flushes hotter than the water.

“Daddy?” His voice is quiet, almost lost in the hum of the jets.

“Hm?” Katsuki’s chin rests on top of his head.

Izuku traces the faint curve. “It’s still… you know. Bloated.”

“I know.” Katsuki’s hand slides down to cover Izuku’s, their fingers lacing together over his stomach. “Sore?”

“A little.” Izuku tilts his head back to look up, finding Katsuki’s crimson gaze already on him. The twinkling lights catch in his father’s eyes. A slow, private smile spreads across Izuku’s face, born from a dizzying, impossible hope. “It feels… different, though. Not just sore. Like something’s… settled.”

Katsuki smiles back and his eyes soften, his thumb rubbing a slow circle over Izuku’s knuckles. He says nothing, just watches him.

“What if I am?” Izuku whispers the question into the steam-filled air. “For real. What do we do?”

Katsuki is silent for a long moment. The jets cycle off, leaving a sudden, heavy quiet broken only by the patter of snow against the glass. “We keep you safe,” he says finally, his voice a low rumble against Izuku’s back. “That’s what we do. No matter what.”

“But how?” Izuku turns in the water, sloshing it over the rim. He braces his hands on Katsuki’s wet shoulders, searching his face. “People will see. Mr. Aizawa already… What happens when I can’t hide it?”

“Let them see.” Katsuki’s hands come up to frame his face, thumbs brushing his cheekbones. His grip is firm, anchoring. “You think I give a single fuck what anyone thinks? You’re mine. Anything that comes from you is mine. That’s the only thing that matters.”

Izuku’s breath hitches. The words should terrify him. They don’t. They feel like a lock clicking shut, a final, irrevocable truth. “You’d really keep us? Both of us?”

“I didn’t take you from her to lose you to anything else.” Katsuki’s gaze drops to Izuku’s mouth, then back to his eyes. “Not even this. Especially not this.”

He leans in then, closing the last inch of steam between them, and kisses him. It’s not like the desperate, claiming kisses from before. This one is slow, deep, a sealing of a promise. Izuku melts into it, the water and his father’s body holding him up, the imagined life inside him feeling suddenly, wonderfully real.

Izuku breaks the kiss with a soft, wet sound, his lips brushing his father’s as he pulls back just an inch. His hips shift in the water, a deliberate, slow roll that drags the soft heat of his pussy along the thick length of Katsuki’s cock, which is already hardening against his thigh.

“Think you can get it up again yet, old man?” Izuku whispers, his green eyes glinting with a challenge that’s all new, born from the safety of the last two days.

Katsuki’s hands, which had been resting on his hips, tighten. A low, playful growl vibrates through his chest and into Izuku’s. “You’re gonna regret that joke, brat.”

He doesn’t give Izuku time to reply. In one fluid, powerful motion, Katsuki hauls him up and turns him, pressing his chest against the cool, slick edge of the tub. The water sloshes violently over the side, a wave hitting the cedar floorboards. Katsuki’s body covers his, a solid wall of heat, and Izuku feels the broad head of his cock nudge against his entrance, already slick from the water and his own arousal.

“Daddy—”

Katsuki drives into him with a single, deep thrust that steals the air from Izuku’s lungs. It’s not slow, not careful. It’s a claiming, a answer to the tease. The water churns around them as Katsuki sets a punishing, relentless rhythm, his hips slapping against Izuku’s ass with a wet crack that echoes in the small room.

Izuku’s fingers scramble for purchase on the porcelain rim, his knuckles white. Every thrust jolts through him, a direct line to his core. “Fuck—!”

“That’s the idea,” Katsuki grunts, one hand fisting in Izuku’s damp green hair, not pulling, just holding. Anchoring. His other hand slides around his hip, fingers finding his clit with unerring accuracy. “Gonna make you come so hard you forget how to talk.”

The dual assault is overwhelming. The deep, stretching fullness of his father’s cock and the rough, circling pressure on his clit coil the tension in Izuku’s belly impossibly tight. His moans are broken, punched out with every thrust. The water jets kick back on, the thrumming bubbles adding a chaotic vibration to the chaos of sensation.

“I can’t— I’m gonna—”

“Do it.” Katsuki’s breath is hot against his ear. “Let me feel it.”

Izuku shatters. His orgasm rips through him with a silent scream, his body seizing, clenching rhythmically around the cock buried inside him. A hot gush of fluid, not just internal but a true, squirting release, mixes with the churning water. He goes boneless, held up only by Katsuki’s grip and the tub’s edge.

Katsuki doesn’t stop. He slows, his thrusts becoming longer, deeper, grinding into the oversensitive, fluttering heat. “One more,” he commands, his voice ragged. “Give me one more.”

“Too much,” Izuku sobs, but his hips are pushing back, seeking the friction again already, his body betraying his words. Katsuki’s fingers resume their work, relentless, and the coil begins winding all over again, faster this time, sharper.

When the second peak hits, it’s a raw, blinding shock. Izuku screams, his vision whiting out, another flood of release pouring out of him. This time, Katsuki follows him, a harsh groan tearing from his throat as he pumps his own release deep into Izuku’s clutching heat, his hips stuttering through the pulses.

For a long minute, there is only the sound of their ragged breathing and the hum of the jets. Katsuki sags over him, his forehead pressed between Izuku’s shoulder blades. The water is still. Izuku feels impossibly full, thoroughly used, and utterly, perfectly safe.

Katsuki’s grip on his hips loosens, his breathing still heavy against Izuku’s damp back. He pulls out slowly, a slick, intimate sound lost in the hum of the jets, and gently turns Izuku around in the water to face him. The movement is careful, almost reverent. He cups Izuku’s jaw, his thumb stroking over a freckled cheekbone, and tilts his face up until their eyes meet. The fierce possession from moments before is still there, but it’s banked now, smoldering in the soft crimson of his gaze. He leans in and kisses him, a slow, tender press of lips that tastes of sweat and shared breath.

“Look at me,” Katsuki murmurs against his mouth, his voice rough but quiet.

Izuku’s eyes flutter open. He’s boneless, floating, held up by the water and his father’s hands. He feels raw, split open, completely known. “I am.”

“Good.” Katsuki studies his face, his own expression unreadable for a long moment. Then he asks, simple and direct, “You okay?”

Izuku nods, his cheek rubbing against Katsuki’s palm. “More than okay.” He swallows, his throat dry. “I feel… empty now. In a good way. Like you took everything that was too much.”

A faint smirk touches Katsuki’s lips. “I put plenty back in, too.” His hand slides from Izuku’s jaw down to his neck, his thumb pressing gently against the frantic pulse there. “Your heart’s still goin’ wild.”

“Whose fault is that?” Izuku’s retort is weak, but a real smile breaks through his exhaustion. He lets his forehead drop to Katsuki’s shoulder.

Katsuki reaches over the edge of the tub, his arm dripping, and twists the hot water tap. A fresh surge of heat swirls around them, steam rising to bead on the cedar ceiling. He settles back against the sloping porcelain, pulling Izuku with him until the boy is sprawled across his chest, ear pressed over his heartbeat. His big, scarred hand rubs slow, firm circles over the knobs of Izuku’s spine.

“I meant it,” Izuku says into the quiet. The words are muffled against Katsuki’s skin. “What I said before. I really want it. To be pregnant.”

Katsuki’s hand doesn’t stop its motion. “I know you did.”

“Is it even possible?” Izuku lifts his head, his green eyes searching. “I mean, with my body… the way it is?”

Katsuki looks at him, his crimson gaze thoughtful, analytical. He’s silent for a long moment, weighing facts, not fantasies. “Chances are low,” he says finally, his voice a low rumble in his chest. “Your system’s not exactly regular. But low isn’t zero. It’s possible.”

Izuku’s breath catches. “So there’s a chance.”

“Yeah.” A slow, predatory smirk spreads across Katsuki’s face. “Means we’ll just have to keep fucking. Round the clock. No days off. Gotta maximize the odds.”

A startled laugh bursts from Izuku, bright and real in the humid air. He shakes his head, his damp green hair sticking to his forehead. “You’re ridiculous.”

“I’m practical.” Katsuki’s hand slides down to cup the swell of Izuku’s ass, possessive even in repose. “You got a problem with the methodology?”

“No,” Izuku whispers, his laughter softening into something warm and sure. He pushes himself up, water sluicing off his shoulders, and leans in to kiss his father. It’s a sweet, lingering press, tasting of heat and shared breath. “No problem at all.”

The water cools around them, turning their skin to gooseflesh. Katsuki reaches over and shuts off the jets, the sudden silence ringing in their ears. He stands first, water cascading off the hard planes of his body, and steps out onto the bathmat. He doesn’t ask. He just leans down, hooks his hands under Izuku’s arms, and lifts him from the tub like he weighs nothing, setting him gently on the mat beside him.

“Stay.” Katsuki grabs a thick, clean towel from the heated rack. He starts with Izuku’s hair, rubbing the curls into a damp, chaotic mess before moving down his neck, his shoulders, over the curve of his back. His movements are methodical, thorough. He kneels to dry Izuku’s legs, the towel rough against his thighs, then stands to pat the soft swell of his stomach. He doesn’t rush. It’s a ritual.

Izuku stands still, letting himself be tended to, watching the water drip from his father’s hair onto his own feet. When Katsuki is satisfied, he quickly towels himself off, a few efficient swipes, then wraps the damp towel around his own hips. He scoops Izuku up again, one arm under his knees, the other behind his back, and carries him out of the steamy bathroom.

The cabin is a wreck. The living room rug is still rumpled from where they’d fucked on it. A cushion lies on the floor by the couch. The kitchen counter glints under the moonlight, still smeared and sticky. Katsuki walks through it all without a glance, his bare feet silent on the pine floor. He carries Izuku up the narrow loft stairs and lays him in the center of the big bed, the sheets still tangled from their marathon sleep.

He climbs in after him, pulling the duvet over them both. The cold linen makes Izuku shiver, but Katsuki pulls him close, tucking Izuku’s back against his chest, his arm a heavy, warm band across his waist. His hand settles low on Izuku’s belly, palm flat. They lie there in the dark, listening to the wind outside, their breathing slowly syncing.

“If you are,” Katsuki says, his voice a quiet rumble against the back of Izuku’s neck. “We don’t tell anyone who I am.”

Izuku stills. “What?”

“To the world, I’m the grandfather. You’re the young father who needs support. We keep the kid safe. We keep us safe. No one needs to know the truth but us.”

Izuku turns in his arms, twisting to look at him. In the faint moonlight from the window, Katsuki’s face is all sharp angles and shadow, but his eyes are steady. “You’d do that? You’d let people think… that?”

“I’d do anything.” Katsuki’s thumb strokes over Izuku’s hip bone. “The truth is ours. What we have in this house, in this bed. That’s the real thing. The outside story is just armor. It keeps them out.”

“But you’d be the father,” Izuku whispers, his throat tight. “You are the father. You should get to be called that.”

Katsuki’s hand slides up to cup his jaw. “I’ll be called ‘Daddy’ by the only person whose opinion matters. The kid will know who I am. They’ll feel it. The rest is just noise.” He leans in, his forehead touching Izuku’s. “We can have our family. Quiet. Ours. No one gets to take it from us. Not your mother. Not some fucking teacher. No one.”

Izuku’s eyes burn. He nods, a small, shaky movement. The idea settles in him, not as a lie, but as a shield. A secret garden only they can enter. He presses closer, burying his face in Katsuki’s neck, inhaling the scent of clean skin and something inherently, uniquely him. “Okay,” he breathes. “Our family.”

Katsuki holds him tighter, his lips pressing a kiss to his temple. “Our family,” he confirms, the words a vow in the dark.