Katsuki’s bladder was a furious, pressing ache. The night’s activities, the gallons of water he’d chugged, it all demanded release. He untangled himself from Izuku’s sleeping form with a grunt, the floorboards creaking under his weight as he stood.

He was halfway to the cabin door when he heard the soft rustle of sheets. A glance back showed Izuku, awake and sliding from the bed, completely nude, his green eyes fixed and wide.

“The hell?” Katsuki rasped, his voice thick with sleep and need. “Go back to sleep, nerd.”

Izuku didn’t answer. He just padded silently across the room to stand close behind him, his body a line of heat against Katsuki’s back. His breath hitched.

“Izuku,” Katsuki warned, hand on the doorknob.

“I want to come with you.”

“To take a piss? You’re not a puppy.” Katsuki tried to shove the door open, but the boy was clinging to his shadow.

“Please, Daddy.”

The title, always a loaded gun, felt different now. Softer, but somehow more desperate. Katsuki sighed, irritation warring with the screaming pressure in his gut. “Fine. Fucking freeze your ass off then.”

He stepped out into the chill pre-dawn air, the forest a wall of black around the clearing. He moved a few paces from the porch, the cold dirt under his feet. Izuku followed, stopping just beside him, his gaze burning a hole in Katsuki’s side.

Katsuki fumbled with his girthy soft cock, his fingers clumsy. “Turn around.”

“No.”

“Izuku.”

“I want to watch,” Izuku whispered, the words pouring out in a rush. “I want to see it. Your cock. When you’re pissing. I want to see it.”

Katsuki froze, his hand stilled. The confession hung in the cold air, absurd and electrifying. He turned his head, staring down at his son. Izuku’s face was flushed, his lip caught between his teeth, his eyes dark and utterly serious. Not teasing. Wanting.

“You’re fucking with me.”

“I’m not.” Izuku’s hand came up, not to touch, but to hover near Katsuki’s wrist. “Please. Let me see.”

The ache in Katsuki’s bladder synced with a sudden, hot pull in his groin.

Izuku didn't wait for permission. He sank to his knees in the dirt, the cold ground biting into his skin, his eyes level with Katsuki’s groin. His fingers trembled as they reached for the thick, soft weight in Katsuki’s grip.

Katsuki’s jaw clenched, a muscle ticking. He didn’t start. He held himself back, the need in his bladder a furious drumbeat. “What are you doing, nerd?”

“I need to see it,” Izuku breathed, his green eyes huge and dark. He leaned in, his hot breath ghosting over Katsuki’s knuckles. “Please, Daddy. Let me look.”

Katsuki’s throat worked. He forced his fingers to uncurl, just enough to let the heavy, uncut length of his cock rest in his palm, exposed to the cold air and his son’s rapt stare. The foreskin was drawn back slightly from the tip, already glistening. Izuku’s lips parted on a silent gasp.

“Look at you,” Katsuki rasped, his voice raw. He watched Izuku’s face, the flicker of shame and the blazing hunger beneath it. “My son. On his fucking knees in the dirt. You a little piss slut, Izuku?”

The word hit Izuku like a physical blow. A full-body shudder wracked him, his cheeks flushing a deep, mortified red. But his gaze didn’t waver. It dropped to the thick vein pulsing along the underside of Katsuki’s cock. “Yes.”

“Say it.”

“I’m your…” Izuku’s breath hitched. He rocked forward, bracing his hands on his own thighs. “I’m your little piss slut, Daddy.”

Katsuki made a low, punched-out sound. The confession, filthy and earnest, sent a bolt of pure heat straight to his own aching cock, which twitched heavily in his hand. “Fuck.”

Izuku moved then, shifting from his knees into a low, wide squat right in front of him. The position splayed his thighs obscenely open, the pale, freckled skin of his inner legs glowing in the weak light. He hooked his fingers into the slick folds of his own cunt, holding himself open, pink and swollen and glistening. He tipped his head back, mouth falling open, his tongue resting on his bottom lip.

“Do it,” Izuku begged, his voice cracking. “Piss on me. Please, Daddy. I want it. I want to taste it. I want you to mark me with it. Piss all over your little slut.”

His tiny chest heaved with each plea, his small, pert tits bouncing with the movement, the dark pink nipples drawn tight into hard peaks. The sight of him—debauched, shameless, and utterly exposed—unraveled the last of Katsuki’s resistance.

“You’re fucking depraved,” Katsuki growled, but it was thick with awe. His free hand came up to cradle the base of his cock, aiming it. He locked eyes with Izuku, who stared back, desperate and worshipful, his tongue outstretched like an offering. “Open wider.”

The first hard, hot stream hit Izuku’s spread cunt directly, a forceful jet that struck his swollen clit and made his whole body jolt. A choked, guttural moan tore from his throat, his hips bucking up into the spray. Katsuki watched, his own breath caught, as the golden arc painted Izuku’s pink folds, dripped down his thighs, and pooled in the dirt between his splayed feet.

“Daddy,” Izuku sobbed, his head falling back, eyes squeezed shut in ecstasy. “Yes.”

Katsuki adjusted his aim, the stream rising up Izuku’s trembling belly, over the soft curve of his tiny tits. It soaked the dark, puffy nipples, making them glisten under the dawn light. Izuku’s hands flew to his own chest, fingers pinching and twisting the sensitive nubs as the hot liquid cascaded over them.

“You like that?” Katsuki gritted out, the relief in his bladder merging with a dark, swelling pride. “My piss on your pretty little tits?”

“I love it,” Izuku gasped, his voice wrecked. He swiped his tongue over his own nipple, tasting it, his eyes rolling back. “More. Please, Daddy, my face. I want it in my mouth.”

Katsuki’s cock jumped in his hand, still pulsing out a steady flow. He tilted his hips, aiming higher. The stream caught Izuku on the chin, then his parted lips, splashing across his flushed cheeks and closed eyelids. Izuku’s mouth opened wider, tongue thrust out, drinking greedily as Katsuki directed the flow straight into it.

Izuku gulped, choked, swallowed. His throat worked desperately, a continuous, low moan vibrating through him. He reached up, his wet fingers tangling in Katsuki’s pubic hair, holding him there, anchoring himself to the source.

“That’s it,” Katsuki murmured, awe softening his gruff tone. “Take it all. My good boy. My filthy little slut.”

The strong stream began to taper, becoming a weaker trickle, then just a soft, continuous drip from his loosened foreskin. Izuku whimpered at the loss, leaning forward before Katsuki could move. He sealed his hot mouth over the dripping tip, his tongue pushing past the foreskin to lap up the last bitter drops directly from the slit.

Katsuki hissed, a full-body shudder rocking him. His spent cock, heavy and sensitive, began to stir again, thickening under the relentless, sucking pressure of Izuku’s mouth.

“Izuku,” he warned, his hand coming down to cradle the back of his son’s head, fingers threading into the damp green curls.

Izuku pulled off with a wet pop, his face gleaming, eyes dazed and satisfied. He nuzzled into Katsuki’s groin, his cheek resting against the now-throbbing length. “Thank you, Daddy.”

Katsuki looked down at him—kneeling in the piss-soaked dirt, marked, owned, and utterly content. His own cock, fully hard again now, ached against Izuku’s cheek. “You’re fucking unreal.”

Katsuki didn’t wait. The sight of Izuku, marked and worshipful, with his own cock throbbing against that filthy cheek, shattered his last shred of restraint. He bent, hooked his hands under Izuku’s armpits, and hauled him upright. “Up.”

“Daddy—?”

He didn’t answer. He spun Izuku around, marched him the few stumbling steps to the nearest thick pine, and shoved him back-first against the rough bark. Izuku gasped, the cold and the scrape a shock against his wet skin.

Katsuki pressed against him, his hard cock sliding through the wet mess on Izuku’s cunt. He gripped Izuku’s hip, his other hand fisting in green curls to yank his head back against the tree. “You liked that, didn’t you?” he growled into his ear. “Getting pissed on like a stray dog in the dirt.”

“Yes,” Izuku choked out, his hands scrambling against the bark, finding no purchase.

“You drank it.” Katsuki’s voice was awe and accusation. He notched his cockhead at Izuku’s entrance, both of them slick with it. “My fucking piss. You swallowed it. You’re sick.”

“I’m yours,” Izuku sobbed, pushing back against him, trying to impale himself. “Please, Daddy, fuck me. I need it.”

Katsuki drove into him in one brutal, unforgiving thrust. The stretch was immediate, searing, familiar now. Izuku screamed, his head cracking back against the tree.

“That’s what you are,” Katsuki snarled, setting a punishing rhythm, the wet slap of their skin echoing in the quiet woods. “My piss slut. My dirty boy. You knelt in the fucking dirt and opened your mouth for it.”

“It was hot,” Izuku babbled, his words jolted out with each thrust. “You—the way it felt—so hot on my cunt—I came just from it, Daddy, I did—”

Katsuki bit his shoulder, a sharp, claiming pain. “I saw. You shook. You gushed. All from my piss.” He pulled his hips back almost all the way, then slammed home again, making Izuku shriek. “You’re fucking depraved.”

“I’m your depraved slut,” Izuku cried, his nails digging into Katsuki’s forearms. “Only yours. Do it again. Piss in me.”

Katsuki stilled, buried deep. A harsh, ragged laugh punched out of him. “What?”

“You have to go again,” Izuku panted, twisting to look back at him, his eyes wild. “I felt it. When you finished. Your bladder’s still full. Do it. Please. Fill me up with it. Piss in my boy pussy, Daddy. Breed me with it.”

The words, so filthy and specific, sent a violent tremor through Katsuki. A low, deep ache in his gut agreed. He was still full. The idea of it—the heat of his release flooding Izuku’s tight, clutching channel—made his vision haze.

“You want that?” he whispered, his voice dangerously soft. He began to move again, slow, deep grinds that made Izuku whimper. “You want me to piss inside this pretty cunt? While I’m fucking it?”

“Yes. God, yes. I want to feel you fill me. I want to be your toilet.”

“Beg.”

“Please, Daddy,” Izuku wept, his body going pliant and desperate against the tree. “Please piss in your slut. I need it. Need you to ruin me with it. Claim me inside. Make me carry it.”

Katsuki’s control snapped. He drove in deep, seated to the hilt, and let go.

The sensation was unreal. A hot, impossible flood erupting from his core, jetting out through his cock into the clenching, wet heat of his son. Izuku felt it instantly—a scalding, internal wave that stretched him even further. He wailed, a raw, broken sound of utter ecstasy.

Katsuki groaned, his forehead dropping to Izuku’s shoulder as he emptied himself, pulse after pulse of hot liquid joining the mess already there. It overflowed, a golden stream mixed with slick dripping down Izuku’s thighs and Katsuki’s own.

Izuku’s body clamped down, then erupted. His orgasm wasn’t a squirt—it was a torrent. A fountain of clear fluid burst from him, mingling with the piss, soaking them both, spraying against the tree and the forest floor. He shook apart, screaming Katsuki’s name, his cunt milking the cock still spurting inside him.

They collapsed together against the tree, a wet, shuddering heap. Katsuki, spent and soft, slipped out of him. A gush of warm fluid followed, pooling at their feet. Izuku trembled violently, his breath coming in ragged, sobbing hiccups.

Katsuki turned him, cradled his filthy face. He kissed him, deep and searching, tasting salt and bitterness and them. “My god,” he breathed against Izuku’s mouth.

Izuku nuzzled into his neck, utterly wrecked. “Yours.”

Katsuki scooped him up, one arm under his knees, the other cradling his soaked back. Izuku’s head lolled against his chest, boneless and spent. He carried him back toward the cabin, their wet bodies leaving a faint, dark trail on the dew-slick grass.

“Daddy,” Izuku mumbled into his skin, his voice shredded.

“Shut up.” The words held no heat. Katsuki shouldered the cabin door open, kicked it closed, and carried him straight into the small bathroom. He set Izuku on his feet beside the shower stall, but Izuku swayed, his legs trembling. Katsuki held him upright with a firm hand on his hip.

He reached in, turned the shower on. The water hit the fiberglass with a hollow drumming, then began to steam. “In.”

Izuku clung to his arm. “You too.”

Katsuki didn’t argue. He guided Izuku under the spray first, then stepped in after him, closing the foggy glass door.

The hot water was a shock, a blissful burn. Izuku hissed, then groaned, tipping his head back. It sluiced over them, washing away the dirt, the sweat, the bitter gold. The water at their feet swirled brown, then cleared.

Katsuki reached for the soap. He worked it into a lather in his hands, then began on Izuku’s shoulders, his touch firm, methodical. He scrubbed down his arms, over his chest, avoiding the sensitive nipples for now. The scent of pine tar soap filled the steamy space.

“You’re a fucking mess,” Katsuki muttered, his thumbs digging into the knots along Izuku’s spine.

Izuku leaned into the touch, his eyes closed. “Your mess.”

Katsuki’s hands stilled for a second. Then he moved lower, soaping the curve of Izuku’s ass, the backs of his thighs. “Yeah. You are.”

He turned Izuku gently to face him. Water cascaded over green curls, plastering them to his forehead. Katsuki soaped his chest again, this time letting his palms brush over the small, soft mounds, the puffy peaks. Izuku shivered.

“Cold?”

“No.” Izuku’s eyes opened, hazy and green through the steam. “Just you.”

Katsuki rinsed him, his hands sliding over the clean skin. He cupped water, washed the remnants of their encounter from Izuku’s face. “Open.”

Izuku opened his mouth obediently. Katsuki let the clean, warm water run over his lips, his tongue. “Swish.” Izuku did, then turned to spit into the drain. The last taste of them, gone.

“Better?” Katsuki asked, his voice lower now.

“Clean,” Izuku whispered. “But I still feel it. Inside. Warm.”

A slow, dark smile touched Katsuki’s mouth. He pulled Izuku against him, skin to slick skin under the spray. “Good. You should.”

He leaned down and kissed him. It was lazy, deep, a slow exploration with no urgency left. Izuku melted into it, his hands coming up to rest on Katsuki’s pecs, fingers splaying over the hard muscle.

They kissed and held each over until the water began to cool.