The gym air smelled of stale sweat and industrial cleaner. Katsuki guided Izuku toward the free weights, his large hand a brand at the small of his son’s back. Izuku’s thin athletic shorts—the ones Katsuki had chosen—left little to the imagination, the dark green fabric clinging to the curve of his ass.

“Leg extensions first,” Katsuki said, his voice a low rumble meant only for Izuku. “Get that pretty little cunt nice and warm for me.”

Izuku’s breath hitched. He could feel the eyes already—the bored housewife on the elliptical, the bulky guy straining at the squat rack. He settled into the machine, his thighs trembling as much from the attention as the impending burn.

Katsuki knelt to adjust the weight. His fingers trailed up the inside of Izuku’s calf, past his knee, digging into the tender muscle of his inner thigh. His thumb pressed, hard, against the seam of the shorts. Izuku jolted.

“Daddy—”

“Focus on the burn, Izu. Don’t think about how wet you are.” He said it just loud enough. The man on the adjacent leg press glanced over, then quickly away.

Izuku pushed the weight, his face flushed. The movement made the thin fabric rub. He could feel the dampness, a slick heat gathering that had nothing to do with exercise. Katsuki’s eyes never left him, a predatory gleam in the fluorescent light.

“Good boy. Now hold it at the top.” Katsuki’s hand came to rest, flat and heavy, on Izuku’s lower stomach, pressing down. “Feel that? That’s your body begging. It knows what it’s for.”

“It’s… it’s for you,” Izuku whispered, the confession torn from him amidst the clank of iron plates.

“Louder.”

“It’s for you, Daddy.”

Katsuki’s smile was all teeth. He helped Izuku off the machine, his arm snaking around his waist, pulling him flush. The thick, hard line of his erection pressed unmistakably against Izuku’s hip through his gym shorts. “Fuck,” Katsuki growled into his hair. “You’re leaking through the fabric. Everyone can see what a slut you are.”

They moved to the bench press. Katsuki lay back, the barbell loaded. “Spot me.”

Izuku stood behind the bench, his position putting him right over his father’s head. As Katsuki pressed the weight up, the muscles in his chest and arms corded, veins standing out. Izuku’s gaze dropped to the prominent bulge straining against Katsuki’s shorts.

“Eyes on the bar, cunny boy.”

Izuku flinched, his eyes darting up. But on the next rep, as Katsuki lowered the weight, his hips arched off the bench. The head of his cock, damp at the tip, peeked over the waistband of his shorts for a full second. A woman across the gym froze, her water bottle halfway to her mouth.

Katsuki racked the weight and sat up, breathing hard. He didn’t adjust himself. He reached back, his hand finding Izuku’s thigh, sliding up under the leg of his shorts. His calloused fingers met bare, wet skin.

Izuku gasped, his hands gripping the bench for support. “They’re… they’re looking.”

“Let them look.” Katsuki’s finger traced a slow, filthy circle. “Let them see what a good boy you are. How you open up for your father.” He pushed a single finger inside, just to the first knuckle. The heat was obscene. Izuku’s knees buckled.

“I can’t—”

“You can. You will.” Katsuki withdrew his hand, bringing his glistening finger to his own mouth. He sucked it clean, his crimson eyes locked on Izuku’s horrified, aroused face. “Tastes like home.”

“Now,” Katsuki growled. In one swift motion, he pulled Izuku down into his lap, the hard line of the weight bench pressing into Izuku’s thighs. Katsuki’s thick erection settled directly against the damp, thin fabric covering Izuku’s pussy. He rocked his hips up, a slow, brutal grind that made Izuku cry out.

“Shh, baby boy. Let them see.” Katsuki’s arms banded around Izuku’s waist, locking him in place as he rolled his hips again, the deliberate friction sparking heat through Izuku’s core. Katsuki’s smirk was a dark, open challenge as he made eye contact with the woman still staring, then the man by the dumbbells. “Look at how my son rides me.”

“Daddy, please,” Izuku whimpered, his hands flying to Katsuki’s shoulders, fingers digging into the damp fabric of his tank top. Every grind dragged his clit against the hard ridge underneath, the soaked shorts offering no protection. “Everyone is—”

“Everyone is getting a free show.” Katsuki punctuated the sentence with a sharp upward thrust. “Feel that? That’s my cock. It’s where you belong. And every single person in this room knows it now.”

He didn’t stop. The rhythm was relentless, a blatant, obscene simulation of fucking right there on the gym floor. Izuku’s head fell back, a choked moan escaping him as the pleasure built, sharp and shameful. He could hear the clanking of weights slow, could feel the weight of numerous gazes.

“You’re dripping all over my shorts, Izu,” Katsuki murmured into his ear, his voice thick with arousal. “Making a mess for an audience. My perfect little slut.”

After a final, grinding roll of his hips that made Izuku shake, Katsuki stood, lifting Izuku with him as if he weighed nothing. He set him on unsteady feet. “Locker room. Now.”

He didn’t let go of Izuku’s wrist, pulling him past the racks and machines. Izuku kept his head down, but he saw the looks—curiosity, disgust, blatant hunger. Five or so men, their own workouts abandoned, fell into step behind them, following toward the men’s locker room door.

The locker room was humid, echoing with the sound of showers. It was empty except for an older man drying off, who quickly gathered his things and left with a frown. Katsuki guided Izuku to a bench in the center of the room. The five other men lingered near the entrance, leaning against lockers, their eyes fixed.

“Strip,” Katsuki commanded, his voice echoing off the tiles. He crossed his arms, his own arousal still tenting his shorts. “Everything. Show them what’s mine.”

Izuku’s fingers trembled as he grabbed the hem of his damp tank top. He pulled it over his head, exposing his small, freckled chest, his puffy nipples already tight. He heard a low murmur from the watching men. He hooked his thumbs in the waistband of his shorts and pushed them down his thighs, stepping out of them. He stood naked, exposed, the air cool on his wet skin.

Katsuki’s crimson eyes swept over him, then over their audience. “You see that?” he said, not to Izuku, but to the room. “That’s a cunny boy. Hairless. Always ready.” He closed the distance, his calloused hand cupping Izuku between his legs, his fingers sliding easily through the slickness there. “See how he opens up for his father?”

“We’re gonna give these strangers a proper show, Izu,” Katsuki whispered, his lips against Izuku’s temple. His other hand circled Izuku’s throat, not squeezing, just claiming. “You’re gonna be a good boy and take everything I give you, right where they can watch.”

“Look,” Katsuki growled, his voice carrying across the locker room tiles. He shoved Izuku’s head down, bending him over the cool, vinyl bench. His other hand spread Izuku’s cheeks apart, exposing the flushed, slick pink of his pussy to the humid air and the hungry eyes of the men. “Look at what I made. This is my son’s cunt.”

Izuku whimpered, his cheek pressed to the bench, his vision filled with the scuffed floor. He could feel the air on his most intimate parts, could hear a low, collective intake of breath from the spectators.

“Soaked,” Katsuki announced, dragging a thumb through the wetness, gathering it. He held his glistening fingers up for the audience. “Dripping for his father. It’s only for me to touch. Only for me to fuck.” He leaned down, his mouth close to Izuku’s ear. “But these perverts get to watch. They get to see how a real man breeds his boy.”

“Please, Daddy,” Izuku moaned, the shame a live wire in his stomach, his hips pushing back unconsciously into Katsuki’s grip.

“Please what, cunny boy? Use your words.” Katsuki’s thumb circled his entrance, not pushing in, just teasing the sensitive rim.

“Fuck me,” Izuku gasped, the words tearing from him. “In front of them. Please.”

Katsuki straightened up, his crimson eyes sweeping over the five, now six, men watching from by the lockers and showers. Their stares were fixed, unblinking. One adjusted himself openly. “You hear that? My baby boy is begging for it. Begging for his daddy’s cock in his incestuous little hole.” He undid the drawstring of his shorts, shoving them down just enough to free his thick, uncut erection. It sprang out, heavy and already leaking, the head dark and flushed.

The sound Izuku made was half-sob, half-sigh. He knew that smell—whiskey and spice and pure Katsuki. He arched his back, presenting himself further, his small chest pressing into the bench.

“Watch close,” Katsuki commanded the room. He spat into his palm, slicking his length, then aligned the broad head against Izuku’s dripping opening. He didn’t push. He just held it there, a promise of stretch, a threat of fullness. “This is where he belongs.”

“Daddy, now,” Izuku pleaded, his fingers scrabbling against the vinyl. The anticipation was agony. The eyes on him were fire on his skin.

Katsuki drove forward in one brutal, claiming thrust, sheathing himself to the hilt inside the tight, clenching heat. Izuku screamed, a raw, unfiltered sound that echoed off the tiles. The bench rattled.

“Fuck,” Katsuki grunted, his hands locking on Izuku’s hips, holding him impaled. “That’s it. Take it. Let them see how deep a son takes his father.”

He set a punishing rhythm, each withdrawal a near-complete escape before he slammed back in, the wet slap of skin echoing in the tiled room. The bench shuddered with every thrust. Izuku’s screams dissolved into choked, rhythmic sobs.

“Louder,” Katsuki grunted, his fingers biting into the soft flesh of Izuku’s hips. “Let them hear what a used cunt sounds like.”

“Daddy, more—call me names,” Izuku begged, his voice shattered, his cheek sliding on the vinyl. “Please, while they watch.”

“My little boy whore,” Katsuki snarled, his pace never faltering. He looked over his shoulder at their audience. The men had shifted closer. One, with a thick beard, had his shorts down, his fist pumping his own cock in time with Katsuki’s thrusts. Another, leaner, had his hand down his pants, his eyes glazed. A third, his back against a locker, had pushed his sweatpants low; his fingers were buried in his own cunt, stroking frantically as he watched Katsuki’s length disappear into Izuku. “Look at them, Izu. They’re jerking off to the sight of you getting ruined.”

“I’m your fucktoy,” Izuku chanted, the words a desperate prayer, his body jolting forward with each drive. “Your cocksleeve—just your fleshlight, Daddy, just yours—”

Katsuki’s growl was pure satisfaction. In one fluid, brutal motion, he pulled out and hauled Izuku up from the bench. He manhandled him, turning him, gripping him under the thighs. He lifted him as if he were weightless, hooking his own arms under Izuku’s knees, locking his hands behind Izuku's neck. The full nelson. Izuku dangled, completely exposed, his back to Katsuki’s chest, his slick, stretched pussy on full display for the room.

“There,” Katsuki rasped, his breath hot on Izuku’s neck. He guided his cock back to Izuku’s entrance, the head nudging against the swollen, sensitive flesh. “Now they can see exactly how I split you open.” He dropped him down, sheathing himself in one deep stroke that punched the air from Izuku’s lungs.

Izuku’s head fell back against Katsuki’s shoulder, a broken wail tearing from his throat. His small breasts bounced with each upward drive, his nipples tight peaks. He could see everything: the six men, all touching themselves, their eyes locked on the place where his father’s thick cock pistoned in and out of his body.

“Watch him cream, you perverts,” Katsuki commanded, his voice ragged with effort. He fucked up into him, hard and deep. “Watch how his little hole milks my cock. See how he was made for this.”

The man with the beard groaned, his pace quickening. The one fingering his cunt moaned openly, his head thrown back. Izuku felt a dizzying rush of power beneath the humiliation. They were all here for this. For him.

“Gonna cum, Daddy,” Izuku sobbed, his body tightening, his inner muscles fluttering wildly around the invading thickness. “I’m gonna squirt all over you in front of them.”

“Do it,” Katsuki hissed, his arms tightening, his thrusts becoming erratic, brutal. “Soak my dick. Let them see you scream.”

Izuku’s body seized, a white-hot wire of pleasure snapping taut from his clit to his spine. He screamed, a raw, unraveling sound, as his cunt clenched and then gushed. A powerful jet of clear fluid shot from him, arcing through the humid air to splatter across the scuffed tile floor. It didn’t stop. A second pulse, then a third, each one making his entire body jerk in Katsuki’s hold, the squirt hitting the legs of the bearded man and the shins of the one fingering himself.

“Fuck, he’s a fountain,” the bearded man grunted, his own stroking hand speeding up, eyes wide.

“That’s it, baby boy, soak everything,” Katsuki snarled into his ear, his own rhythm breaking into short, brutal thrusts. He buried himself to the root and held, his hips stuttering as his cock pulsed deep inside the fluttering, drenched heat. Izuku could feel the hot flood of his father’s release filling him, wave after wave, marking his insides in front of everyone. Katsuki’s groan was a low, possessive rumble against his back. “Taking my cum right where they can see it pool inside you.”

Slowly, Katsuki’s arms loosened. He lowered Izuku until his bare feet touched the cold, wet tile. Izuku’s legs buckled, but Katsuki’s hand clamped on his hip, holding him upright, keeping his father’s softening cock lodged inside him. Katsuki looked over Izuku’s shoulder at the panting, flushed audience. “You see that? He’s full of me. But the show’s not over.” He gave a rough, commanding nod. “You’ve been good spectators. Finish it. Cum all over my son.”

Izuku’s breath hitched. His hands, trembling, came up to his small breasts. He pinched his own puffy brown nipples, rolling them between his fingers, a fresh trickle of arousal mixing with the cooling mess on his thighs. “Please,” he whispered, then louder, his voice hoarse from screaming. “Please, cover me. I’m just a canvas. Paint me.”

The bearded man was the first. He staggered forward with a choked groan, his fist a blur on his thick cock. He aimed at Izuku’s chest. The first hot stripe landed across Izuku’s collarbone. The second splashed over one peaked nipple. Izuku moaned, arching into it.

“Atta boy,” Katsuki murmured, his hand sliding around to cradle Izuku’s stomach, pressing him back against his own spent body. “Look how pretty he looks begging for your filth.”

The lean man came next, adding his release to Izuku’s freckled shoulder. The one who’d been fingering his cunt approached, squirting over Izuku’s trembling thigh. One by one, the others stepped up, until Izuku was streaked and dripping with them, the mixed scents of sweat and sex and strangers thick in the air. He kept his eyes locked on Katsuki’s reflection in the foggy mirror across the room, seeing the dark satisfaction there.

When the last man finished, zipping up and stepping back with a shaky breath, the locker room fell into a heavy, post-coital silence, broken only by the drip of a showerhead. The spectators began to disperse, avoiding each other’s eyes, slipping out the door without a word.

Katsuki finally pulled out of him. The sound was obscenely wet. Izuku felt the loss, the sudden empty ache, and the trickle of combined fluids down his inner thigh. Katsuki turned him around. His crimson eyes were hooded, intense, as he surveyed the mess painting Izuku’s skin. He swiped two fingers through the streaks on Izuku’s chest and brought them to Izuku’s lips.

“Taste it,” he commanded, his voice a gravelly whisper. “Taste what you asked for.”

Izuku opened his mouth without hesitation, his tongue swirling around the offered fingers, sucking them clean. The salt-bitter taste made his spent cunt give a feeble, aching throb. “Thank you, Daddy,” he whispered against the skin.

Katsuki didn’t smile. He just watched him, his thumb tracing Izuku’s swollen bottom lip. “My good boy,” he said, the words leaving his mouth like a confession. “My filthy, perfect fuck toy.”