The water in the bathroom sink ran clear. Izuku scrubbed his hands until they were red, the soap smell sterile and wrong. He straightened his old queen size childhood bed, pulling the comforter tight over the stains he couldn’t see but could feel in the ache between his legs. Every movement was careful, deliberate, a performance of normalcy for an audience of one: himself. He smoothed his holiday sweater, took a breath that didn’t settle, and opened the door.

Katsuki was right there. Leaning against the wall opposite, arms crossed, a statue of contained tension. He’d been waiting.

They stared. The hallway was too quiet, the distant hum of the party downstairs a world away. Izuku’s throat worked. No words came. Katsuki’s eyes—crimson and unreadable—tracked over Izuku’s face, down his throat, to the collar of his sweater. His jaw was a hard line.

“You clean up?” Katsuki’s voice was gravel, low.

Izuku nodded. His own voice was a whisper. “Yeah.”

“Good.”

Another silence, thick and choking. Izuku’s fingers twisted in the fabric of his sweater. Katsuki shifted his weight, the floorboard creaking under his foot. His gaze dropped to Izuku’s mouth, then flicked away, a muscle ticking in his cheek.

“We can’t just—” Izuku started.

“We aren’t doing anything,” Katsuki cut him off, but it lacked its usual force. It sounded like a question.

Footsteps sounded on the stairs—confident, familiar. They both froze, a deer-in-headlights unison that was more intimate than anything that had happened in the bedroom. Mitsuki’s spiky blonde head appeared, then the rest of her, taking the steps two at a time.

“There you two are,” she said, her voice carving through the tension like a knife. She stopped on the landing, hands on her hips, sharp red eyes scanning them. “The hell’d you disappear to? Your mother’s looking for you, Izuku. Shoto’s being polite but he looks like a lost puppy.”

Katsuki straightened, his mask slamming into place. “Pipe was leaking under the sink in the guest bath. Nerd was helping me check it.”

Mitsuki snorted. “Since when do you know plumbing?”

“Since when do you?” he shot back, the familiar abrasiveness a relief. “Just needed a second set of hands to hold the flashlight. It’s fine.”

She looked between them, a flicker of something—suspicion, curiosity—in her gaze. Then she shrugged. “Whatever. Don’t hide all night. It’s rude.” She moved past them, heading for the guest bedroom opposite of the master down the hall. “I’m grabbing a sweater. This house is a damn icebox.”

The moment her door clicked shut, the air crackled back to life.

Izuku moved before he could think. His hand dove into the pocket of his jeans, fingers closing around damp, delicate lace. He stepped into Katsuki’s space, close enough to smell the cologne and sweat and him. Katsuki didn’t move, just watched him, eyes narrowed.

“Here,” Izuku breathed, the word barely audible. He shoved the bundled fabric into the open front pocket of Katsuki’s jeans, his knuckles brushing the hard plane of Katsuki’s thigh through the denim.

Katsuki looked down, then back up at Izuku’s face. “What the fu—”

But Izuku was already turning, already fleeing, his socked feet nearly silent on the polished wood as he hurried for the stairs. He didn’t look back.

Katsuki stood frozen. The echo of Izuku’s retreat faded. The party sounds swelled from below. He waited three heartbeats, then his hand slipped into his pocket.

His fingers met the lace. He pulled the garment out, held it in the dim hallway light.

Black. Lacy. A delicate, feminine cut. The pair Izuku had been wearing. They were damp, soaked through in the center, the fabric cool and clinging to his fingers. He brought them closer to his face, a brutal, involuntary motion.

The scent hit him first. Not just laundry soap or skin. This was musk, sharp and sweet, the unmistakable, intoxicating smell of Izuku’s arousal. Of his release. Of the squirt that had coated Katsuki’s cock and the sheets less than an hour before. It was fresh. It was him.

A low groan tore from Katsuki’s chest. Heat, immediate and savage, flooded his groin. His cock, which had softened to a heavy, spent ache, jerked back to life against his thigh, thickening, hardening with a pulse that was pure animal demand. The lace was a live wire in his hand. He could see it, the moment in the hallway, Izuku watching him, touching himself, making this mess. For him.

He crushed the fabric in his fist, bringing it to his nose again, inhaling deep. His other hand pressed against the front of his jeans, palming the rigid outline of his erection through the denim. It was back. Ten inches of aching, desperate want, all because of a scrap of lace and the scent of his nephew’s shame.

Downstairs, a laugh rang out. Shoto’s, maybe. Katsuki’s eyes slid shut. He stood there in the empty hallway, fist clenched around the panties, cock throbbing, utterly and completely fucked.

He didn’t go far. Just the hall bathroom, the one guests used. He locked the door behind him, the click echoing in the small, tiled space. The panties were still crushed in his fist.

“Fuck,” he whispered to the empty room. The word hung in the air, useless.

He leaned back against the door, the wood cool through his shirt. His other hand went back to his cock, still hard, straining the zipper of his jeans. He rubbed the heel of his palm against the head, a rough, punishing grind. It wasn’t enough.

With a sharp, frustrated motion, he popped the button of his jeans, dragged the zipper down. He freed himself, his cock springing out, thick and flushed and desperately erect. The cool air of the bathroom made him hiss. He looked down at it, at the evidence, then at the black lace in his other hand.

“You little shit,” he muttered, but there was no heat in it. Only a ragged kind of awe.

He didn’t unfold them. He brought the damp, bundled fabric to his nose again, inhaling deeply, letting Izuku’s scent—musk, salt, that sweet, private slickness—flood his senses. His eyes slid shut. His fist tightened around the lace. With his other hand, he wrapped his fingers around the base of his cock, giving himself one long, slow stroke from root to tip. The pre-cum beading at his slit smeared wet and slick.

He opened his eyes. Stared at the lace in his hand. Then, moving with a deliberate, brutal slowness, he began to wrap the damp fabric around the head of his cock. The lace was cool at first, then warmed instantly against his skin. He could feel the wet patch, right where Izuku had been soaked through, pressed against the most sensitive part of him.

“Christ,” he choked out. His hips jerked forward into the makeshift, intimate sheath.

He started to stroke. Slowly at first, the lace dragging against his skin with a faint, wet sound. Every upstroke pulled the scent up to his face. Every downstroke coated his length in Izuku’s essence. He could see it—the hallway, the cracked door, Izuku’s hand moving under his sweater, his face wrecked and wanting. For him.

“Were you watching me, Izuku?” he growled to the mirror, to his own reflection, eyes wild. “Did you like it? Seeing me lose my goddamn mind over you?”

He stroked faster. The lace was soaked now, from both of them. The friction was perfect, maddening. He leaned his head back against the door, his breathing coming in ragged pants. His thumb rubbed rough circles over the wet lace at his tip.

From downstairs, a burst of laughter. Cheerful. Normal. It sliced through the haze. His rhythm faltered.

His fist tightened on his cock, a spasm of shame. It didn’t stop the heat. It just made it hurt. He was here, in his sister's bathroom, fucking his fist with her son's dirty panties, while the nerd’s perfect fiancé laughed with his family downstairs.

“Fuck it,” he snarled, the anger white-hot and directionless.

He drove into his grip, fast and punishing, the image of Izuku’s scared, defiant face shoving the panties into his pocket flashing behind his eyelids. That was the trigger. The surrender. The gift. His back arched off the door, a low, guttural groan tearing from his throat as he came, hard, stripes of release painting the white tile floor between his feet. He kept stroking through it, milking himself, until he was soft and oversensitive in his soiled, lace-wrapped hand.

He stood there, panting, spent. The panties were a ruined, sticky mess in his palm. The smell of sex and shame filled the small room. He looked down at the mess on the floor, then at his own reflection—flushed, hollow-eyed, defeated.

He was so, so fucked.

Katsuki stood panting in the bathroom, surrounded by the smell of sex, utterly defeated. He looked down at the ruined lace in his hand, sticky and damp. A prize. A condemnation. He couldn’t leave it here. With a slow, deliberate motion, he wiped the worst of the mess from the fabric onto a wad of toilet paper, flushed it, then folded the panties into a damp, compact square. He shoved them deep into the front pocket of his jeans. They rested there against his thigh, a secret heat.

He zipped himself up, the denim tight over his sensitive, spent cock. His eyes caught on his left hand as he fastened the button. The wedding band, a simple platinum loop, gleamed dully under the harsh bathroom light. He stared at it. The metal felt suddenly heavy, a cold, perfect circle of betrayal. Eijiro’s laugh, warm and trusting, echoed in his memory. He closed his hand into a fist, hiding the ring against his palm.

“Fuck,” he whispered again, to no one.

He ran the sink, splashed cold water on his face. The reflection in the mirror was a stranger—flushed skin, hollow eyes, the ghost of his own depravity hanging in the air around him. He couldn’t meet its gaze for long. He dried his hands and unlocked the door.

The hallway was empty. The party sounds from below were a wave of normalcy that hit him like a physical barrier. Laughter. The clink of glasses. Toshinori’s deep, rumbling voice telling a story. He placed a hand on the wall, steadying himself. The other hand drifted to his pocket, fingertips pressing against the damp lace within. A spark of heat, faint and shameful, flickered in his gut.

He took the stairs slowly, each step a conscious effort. The wood creaked under his weight. The scent of the house—pine, baking cookies, his sister’s perfume—overwhelmed the intimate musk still clinging to his skin. It was a lie. He was a lie, walking back into the light.

The living room opened before him, a scene of holiday warmth. Inko was refilling a tray of appetizers. Toshinori and Shoto were by the fireplace, Shoto listening with his usual quiet focus. And there, on the couch, curled into Shoto’s abandoned spot, was Izuku. He had a throw blanket wrapped around his shoulders, pulled up to his chin. His eyes, wide and green, snapped to Katsuki the moment he appeared.

They stared at each other across the room. A current passed through the space, silent and electric. Izuku’s gaze dropped to Katsuki’s pocket, then flicked back to his face. A faint, unreadable tremor passed over his features.

“There you are!” Mitsuki’s voice cut through the tension. She emerged from the kitchen, a fresh drink in hand. She eyed her son. “Took you long enough. Plumbing issue my ass. You look like hell.”

Katsuki tore his eyes from Izuku. “House is dry. Just needed a minute.”

“Well, your minute’s up.” She shoved the drink at his chest. He took it automatically. “Go be social. You’re looming.”

She moved past him towards Inko, her daughter. Katsuki was left standing on the periphery, the cold glass in his hand, the warm, damp secret in his pocket, and Izuku’s eyes still on him, watching, always watching.