Chapter 10: The Knotting Serum
The collar sat heavy in his hands, a cold shackle of potential and promise. Kan turned it over, watching the lamplight catch the hammered silver ridges, the intricate engravings that seemed almost alive, shifting and writhing in the flickering glow. The weight was substantial—not just metal, but meaning.
Phra Chan watched him with those gold-flecked eyes, patient as a statue. "You may try it on here, if you wish. Or you may wait until you're somewhere more... private. The choice is yours."
Kan's jaw tightened. He wanted to try it. More than he'd wanted anything in a long time. But the thought of exposing that vulnerability in front of this stranger—this man who seemed to see through him like glass—made his stomach twist.
"Private," he said, his voice steadier than he felt. "I'll wear it tonight."
Phra Chan's smile was approving. "Wise. Some things are best experienced without an audience. At least the first time."
He rose, extending his hand. Kan took it automatically, surprised by the warmth and strength of his grip. Rei moved closer, a silent sentinel at his side.
"I look forward to seeing you again, Kan," Phra Chan said. "I suspect you will be very interesting indeed."
They left the Crimson Garden in a haze, the cool night air hitting Kan's face like a splash of water. The collar was tucked inside his jacket, pressing against his chest like a second heartbeat. He could feel it there, an insistent reminder of what lay ahead.
Rei drove them back in silence, his hands tight on the wheel. The city blurred past them—neon signs, crowded streets, the distant gleam of the river. By the time they reached their apartment, Kan's nerves were stretched thin as wire.
He placed the case on the bed and opened it, staring down at the collar and cuffs. They seemed to glow in the dim light, their engravings catching shadows.
"Kan." Rei's voice was careful. "You don't have to do this. Not tonight. Not if you're not sure."
"I am sure." Kan's voice was rough. "I've never been surer of anything."
"Then let me do it." Rei stepped closer, his hand reaching for the collar. "Let me put it on you."
Kan's breath caught. He nodded.
Rei picked up the collar, his fingers brushing the cool metal. Then he stepped behind Kan, and Kan felt the silver settle around his neck. The click of the clasp was deafening in the quiet room. Rei's hands lingered on the metal, tracing the edge where it met Kan's skin.
"How does it feel?" Rei asked, his voice low.
Kan swallowed, feeling the collar shift against his throat. "Heavy. Like... like something's changed."
"Let me see you."
Kan turned. Rei's gaze swept over him—the collar glinting at his throat, the way it caught the light. His expression was unreadable.
"You're beautiful," Rei said finally. "Like something out of a dream."
Kan's cheeks flushed. "It's just a piece of metal."
"No." Rei shook his head, his hand coming up to cup Kan's face. "It's not. It's a promise. A statement. You're telling the world that you belong to someone. That you chose to belong."
The words hit harder than they should have. Kan's eyes stung, and he blinked rapidly, looking away.
"I didn't think it would feel like this," he admitted. "I thought it would be... I don't know. Hot. Exciting. I didn't think it would feel like—"
"Like coming home?"
Kan's gaze snapped back to Rei's. The words hung between them, raw and honest.
"Yeah," Kan whispered. "Like coming home."
Rei kissed him then, slow and tender. His hands threaded through Kan's hair, careful of the collar, grounding him. When they broke apart, Rei's forehead rested against Kan's.
"I have something for you too," Rei said. "From Phra Chan. A different serum."
Kan's heart skipped. "What kind?"
Rei moved to the bedside table, pulling out a small vial. The liquid inside was milky white, swirling with opalescent threads. "It's a variation of what I took before. But instead of just making me larger... it gives me a knot."
"A knot?" Kan's mouth went dry.
Rei's eyes were dark with a hunger that made Kan's knees weak. "You'll feel it when it takes effect. It'll swell at the base of my cock, and then—" He paused. "Then it won't come out until I come."
Kan's breath came faster. The thought of it—of being locked together with Rei, unable to separate until the inevitable flood—sent a shiver down his spine.
"What are you waiting for?" Kan asked, his voice barely a whisper. "Take it."
Rei uncorked the vial, swallowing the contents in one quick motion. For a moment, nothing happened. Then his body went rigid, a low groan escaping his lips. His cock began to swell immediately, thickening and lengthening until it was even more grotesque and magnificent than before. But this time, the changes didn't stop there.
Kan watched, transfixed, as a ridge began to form at the base of Rei's shaft. It grew slowly, a ring of flesh that expanded outward, becoming a thick, bulbous knot the size of a fist. Rei's breath was ragged, his hands gripping the sheets as he endured the transformation.
"Fuck," Rei managed, his voice strangled. "That's... that's intense."
Kan's hands were shaking as he reached out, brushing his fingers against the swollen flesh. It was hot and pulsing beneath his touch, a living thing that seemed to have a heartbeat of its own.
"I want it inside me," Kan said, his voice thick with desire. "Now."
Rei pulled him onto the bed, positioning Kan on his hands and knees. Rei pressed the massive head against Kan's entrance, and Kan gasped at the pressure. The serum had made him even larger than before—impossibly, devastatingly so. The knot at the base was still swollen, waiting.
"Relax," Rei murmured, his hands rubbing circles into Kan's hips. "Let me in."
Kan breathed out, forcing his body to yield. The head pushed inside, stretching him wide, and he cried out at the familiar but still overwhelming sensation of being filled. Inch by inch, Rei slid deeper, until his pelvis was flush against Kan's ass.
There was a pause. Kan could feel the knot pressing against his stretched rim, pulsing, waiting.
"Take a breath," Rei said. "This is going to be... a lot."
Kan did. And then Rei pushed.
The knot forced its way inside, and Kan screamed. The stretch was blinding, white-hot, so overwhelming that his vision blurred. He felt impossibly full—more than he'd ever felt before—his body struggling to accommodate the massive swelling at his base.
"Fuck—" Rei's voice was ragged. "Fuck, Kan, you're so tight—"
"Move," Kan gasped. "Please, Rei, just move—"
Rei pulled back, and Kan felt the knot shift inside him, dragging against his walls. Then Rei thrust forward, and the impact sent shockwaves through Kan's entire body. The knot pressed against something deep inside him, and Kan saw stars.
"Yes," he sobbed. "Yes, there, right there—"
Rei picked up the pace, his hips snapping against Kan's with brutal precision. The room filled with the sounds of their bodies—wet, sticky, obscene. The ceiling mirror showed Kan's face, wrecked and tear-stained, the collar glinting at his throat, his body jerking with each thrust.
Rei leaned over, his chest pressing against Kan's back. His mouth found Kan's shoulder, biting down as he drove in deep. His hands snaked around Kan's front, find his chest, his fingers finding Kan's nipples.
Kan gasped as Rei's fingers found his nipples—hard, sensitive buds that had never been the focus of attention before. But now, under the influence of everything they'd done, they were hypersensitive, aching. Rei rolled them between his thumb and forefinger, and Kan's entire body seized.
"Fuck—" Kan's voice broke. "Oh god, Rei—"
"Do you like that?" Rei breathed against his ear. "Having your nipples played with while I fuck you?"
"Yes—" Kan was barely coherent. "Yes, please, more—"
Rei pinched harder, twisting the tender flesh. Kan screamed, his cock hardening still further, dribbling fluid. The sensation was electric, traveling straight to his prostate, amplifying every thrust. Rei worked him mercilessly, alternating between gentle strokes and harsh pinches, driving Kan to the brink of madness.
The knot was swelling, growing even larger inside him. Kan could feel it pulsing, expanding, locking them together. He was so full he couldn't breathe. Every movement, every shift of Rei's hips, sent fresh waves of agony and ecstasy crashing through him.
"I'm going to come," Rei warned, his voice tight with strain. "The knot—it's locked in. I can't pull out—"
"Don't," Kan begged. "Don't pull out. Fill me up. I need it—"
Rei slammed into him one final time. Kan felt the knot swell to its full size, locking them together, and then—a flood.
The first pulse of come was so hot, so thick, that Kan's entire body convulsed. More followed, endless, pumping into him like a fire hose. Kan's belly began to swell, distending obscenely. He looked down, saw the bulge in his stomach growing larger and larger, and his own cock erupted.
He came violently, his vision whiting out. His body seized, his hole clenching and unclenching around Rei's huge cock and knot. He could feel the come still pumping into him, filling him to the brim and beyond, overflowing and dripping down his thighs.
Belatedly, he became aware that he was crying. Great, heaving sobs shook his body as the waves of pleasure continued to roll through him. His hands clawed at the sheets, his knees giving out. Rei followed him down, still buried inside, his weight pressing Kan into the mattress.
The knot pulsed again, and another load flooded Kan's already-swollen belly. Kan screamed, his voice raw and spent. He felt so full, so impossibly, utterly full—a sensation that was equal parts sublime and unbearable.
"Please," Kan sobbed. "Please, Rei, I can't—it's too much—"
But he didn't want it to stop. He never wanted it to stop. The fullness was a revelation, a divine torture. He bucked against Rei, trying to take more, even as his body screamed for mercy.
Rei's hands came down, pressing against the bulge in Kan's stomach. Kan gasped as his fingers traced the outline of his own cock through Kan's skin, massaging the taut, stretched flesh.
"I can feel myself inside you," Rei murmured, wonder in his voice. "You're so full, Kan. So fucking full—"
"I'm going to burst," Kan whimpered. "You're going to break me—"
"I know." Rei's voice was dark, possessive. "And I want to see it happen."
The knot pulsed again, and Kan's eyes rolled back. His body was wracked with pleasure, each new flood of come sending him spiraling deeper into the abyss. His belly was distended now, an obscene bulge that made him look pregnant with Rei's seed.
He came again, though he had nothing left to give. His cock twitched, empty, a few pathetic drops of fluid leaking out. But his body continued to seize, trapped in an endless cycle of pleasure and pain.
They lay there, locked together, for what felt like hours. The knot slowly began to shrink, allowing Rei to pull out with a wet, obscene sound. A flood of come spilled out of Kan's gaping hole, pooling on the sheets beneath him.
Kan collapsed, boneless, his breath coming in ragged gasps. His belly was still swollen, his hole wrecked, but he was alive. More than alive.
"Stay," Kan murmured, reaching back for Rei's hand. "Don't go. Not yet."
"I'm not going anywhere," Rei said, pressing a kiss to his shoulder. "I'll stay as long as you need me."
Kan drifted into a haze, half-conscious. The collar was still around his neck, a comforting weight. He reached up, touching it, feeling the metal warm from his skin.
"Tonight showed you something, didn't it?" Rei asked, his voice soft and low. "What submission can really feel like."
Kan's throat tightened. "It showed me a lot of things. About myself. About us." He turned to meet Rei's gaze, his eyes hazy but searching. "About what I might need."
"And what do you need?" Rei asked, his thumb stroking Kan's cheek.
"To be held like I'm something precious," Kan whispered. "Even when I'm being used like a toy. Maybe especially then."
Rei let the words settle in the air between them. His hand came to rest on the collar, stroking the cool silver.
"I can do that. I can hold you through the hard parts." His voice dropped to a rough, sincere whisper. "But if we do this—if we explore Phra Chan's world together—we'll go until we can't anymore. No half-measures. No escape hatches. Are you ready for that?"
The dark of the room was quiet, the only sound the distant hum of the city beyond the windows. Kan shifted, feeling the slick heat between his thighs, the heavy weight of the collar against his throat.
"I've been ready my whole life," Kan said. "I just didn't know it until I met you."
The words hung in the air like smoke, curling around them in the dim light of the bedroom. Rei's hand was still on the collar, stroking the silver as if it were a part of Kan's skin now, an extension of his very being. The weight of it had settled into Kan's bones, a truth he'd been circling for years without ever having the language to name it.
"I've been ready my whole life," Kan said. "I just didn't know it until I met you."
Rei's breath hitched. His hand slid from the collar to the curve of Kan's jaw, tilting his face up. "Do you trust me, Kan?"
"With everything I have." The words came out without hesitation, raw and honest. "I trust you to break me. I trust you to put me back together. I trust you to know when I need to be taken apart."
Rei's eyes darkened. "I want to give you something. Something I've never given anyone."
Kan's heart hammered."What?"
"Everything." Rei's voice was barely a whisper. "I want to give you everything."
The kiss that followed was different from any they'd shared before. It was hungry, desperate, but also tender—a promise sealed in the press of lips and the slide of tongues. Kan melted into it, his body still aching from the night before, but the pain was a sweet reminder of what they'd done and what they'd do again.
When they broke apart, Rei's hands were already moving, finding the hem of Kan's shirt. "I want to watch you come undone again. But this time, I want you to look me in the eyes when you break."
Kan felt his skin flush. "I don't know if I can—"
"You can." Rei's voice was firm. "You'll look at me, and you'll let me see everything. All of it. The parts you hide. The parts you're ashamed of. I want to see them all."
The shirt came off. Then the pants. Kan stood naked before Rei, the collar at his throat the only thing he wore. The ceiling mirror reflected them back—Kan's body, still marked with bruises and bite marks from their earlier passion, and Rei, fully clothed, a dark silhouette against the amber light.
"Lie down," Rei said.
Kan obeyed, settling onto the bed, his body spread out like an offering. The sheets were still damp from their previous encounter, the smell of sweat and sex heavy in the air. Rei moved to the foot of the bed, his hands working at his own belt.
Watching Rei undress was its own kind of torture. Every movement was slow, deliberate, designed to make Kan ache with anticipation. The shirt peeled away, revealing the lean muscles of Rei's chest. The pants slid down, freeing his cock—already half-hard, already thick enough to make Kan's mouth water.
"What do you want tonight?" Rei asked. His voice was casual, but his eyes burned."Tell me. Tell me what you need."
Kan swallowed hard. Words seemed too small, too fragile for what he was feeling. But Rei was waiting, patient, and Kan knew he needed to find the words.
"I want you to use me," Kan said. "I want to feel owned. I want to feel like every inch of me belongs to you, and when you're done, when you've taken everything you need..." He paused, his voice dropping. "I want to feel your come inside me. I want to see my belly swelling from it. I want to pretend—" He stopped, his face flushing.
"Pretend?"Rei prompted.
"I want to pretend it's real. That I'm real. That I could actually—" Kan's voice broke. "That I could actually carry your child."
The confession hung in the air, heavy and raw. Rei's expression shifted, something dark and possessive flickering across his features.
"You want to be bred," Rei said. It wasn't a question.
"Yes." Kan's voice was barely audible. "I want to feel like I'm yours so completely that it changes me. That it leaves something behind."
Rei was on him in an instant, his body covering Kan's, his mouth claiming his in a kiss that was all teeth and hunger. His cock pressed against Kan's thigh, thick and leaking, and Kan arched into the contact.
"Get on your knees," Rei growled. "I want to fuck you until you can't remember your own name."
Kan scrambled to obey, turning onto his hands and knees. His body was still sore from the night before, his entrance still stretched and loosened, but the thought of Rei filling him again sent a fresh surge of heat through his veins.
"Look at you," Rei breathed. "Already open. Already wanting me."
"Please," Kan begged. "Please, Rei, I need you inside me—"
Rei positioned himself behind Kan, his cock pressing against Kan's entrance. But instead of pushing in, he paused, his hand coming up to grip Kan's hip.
"What do you want me to do?" Rei asked. "Tell me."
"I want you to fuck me until I can't think," Kan said, his voice trembling. "I want you to fill me until I'm overflowing. I want—" He broke off, a sob catching in his throat. "I want to feel you everywhere. Inside me.Around me. I want to be so full that I can't tell where I end and you begin."
Rei's breath was ragged. "That's what I wanted to hear."
He pushed in, and Kan screamed.
The angle was different this time, deeper somehow, even though Rei's cock was merely its natural size this time. Each inch was a revelation, filling a space Kan hadn't known he was empty. Kan's fingers clawed at the sheets as Rei bottomed out, his balls pressing against Kan's ass.
"Don't move," Rei commanded. "Don't move until I tell you."
Kan froze, trembling. Rei reached around, his hand finding Kan's nipple, pinching it hard enough to make Kan gasp. The pain shot through him, and his cock twitched, leaking against his belly.
"Such a needy little slut," Rei murmured. "Look at you. Taking me so well. Getting so wet for me."
"I'm not wet," Kan managed, his voice strained."No?" Rei withdrew almost entirely, then slammed back in. "Then why does it feel like you're dripping for me?"
Kan couldn't respond. Words were beyond him now, reduced to sounds—gasps, moans, half-formed pleas. Rei set a brutal rhythm, each thrust driving deep, hitting that spot inside Kan that made everything go white.
"Do you want to be bred?" Rei asked, his breath hot against Kan's ear. "Do you want me to fill you until you're bursting?"
"Yes—" Kan sobbed. "Yes, please, I need it—"
Rei pulled out suddenly, leaving Kan empty and aching. Before Kan could protest, Rei was flipping him over, pinning him to the mattress with his body. His hands came up to Kan's neck, not choking, but resting there, a possessive weight.
"Look at me," Rei said. "I want to watch your face when I fill you."
Kan's eyes locked onto Rei's. He watched as Rei positioned himself, watched as the head of his cock pressed against Kan's entrance. Then Rei pushed in, slow, relentless, filling him inch by inch until their bodies were flush.
"You're mine," Rei said, his voice low and certain. "Every inch of you. Do you understand?"
"Yours," Kan echoed. "I'm yours."
Rei began to move, a slow, grinding rhythm that had Kan arching off the bed. His hands found Kan's nipples again, twisting them, and Kan cried out, the sensation electric.
"Please—" Kan was barely coherent. "I need it deeper—"
Rei adjusted his angle, driving in harder, and Kan's eyes rolled back. The room was filled with the sounds of their bodies—wet, obscene, the slap of skin against skin. Kan could feel himself approaching the edge, his cock throbbing with each thrust.
"Not yet," Rei commanded. "Don't come until I tell you."
Kan's body was screaming, every nerve on fire. He couldn't hold back—couldn't do anything but grip Rei's shoulders and ride the waves of sensation. The collar was a tight band around his throat, reminding him that he was owned, that he belonged to this man in every way that mattered.
"Now," Rei gasped. "Come now, Kan. Let go."
Kan shattered.
His body convulsed, his cock erupting between them, painting both their chests with his release. Rei followed a second later, slamming into Kan's hole, a deep, guttural growl rising from his chest as he came, filling Kan with a flood of heat that seemed to go on forever.
But even as the waves receded, Rei didn't stop. He kept thrusting, each movement drawing out his orgasm, pumping more come into Kan's already-full belly. Kan was pinned beneath him, gasping, his body shaking with overloaded pleasure.
"Stay," Rei ordered. "Don't move."
Kan couldn't have moved if he'd wanted to. He lay there, his body limp, his belly slightly distended with Rei's seed. Rei pulled out slowly, deliberately, and Kan felt the emptiness immediately.But Rei wasn't done. He reached for something on the bedside table—a small, silver object Kan didn't recognize. Before Kan could ask, Rei was pushing it inside him, a smooth, rounded plug that settled against his inner walls.
"No leaking," Rei said, his voice dark with satisfaction. "I want you to keep every last drop inside you."
Kan's breath caught. The plug was cold, but it was warming to his body temperature, a constant pressure that reminded him of what had just been done to him.
"Turn over," Rei said. Kan obeyed, his body moving on its own, rolling onto his stomach. Rei's hands came up, stroking the bulge of the plug through Kan's skin. His touch was gentle now, almost reverent."How do you feel?" Rei asked.
"Full," Kan whispered. "So full."Good." Rei's hand pressed against Kan's belly, gentle but firm, making Kan wince at the pressure. "I want you to feel full all night. I want you to feel me inside you every time you move, every time you breathe."
Kan's vision blurred with tears. Not tears of pain or shame, but of overwhelming emotion. He felt like he was floating, suspended in a state of pure, naked need.
"Rei," he managed, his voice cracking. "I think... I think I love you."
The silence that followed was heavy with meaning. Rei's hand stilled on his belly, and for a moment, Kan was terrified he'd said the wrong thing.
But then Rei was moving, turning Kan onto his back, cupping his face in both hands. His eyes searched Kan's, looking for something—and whatever he found made his expression soften into something almost vulnerable.
"I think I love you too," Rei said. "Even though I don't know how to say it right."
"You just did," Kan whispered.
The kiss was gentle, almost chaste, a strange contrast to the raw sex that had come before. But it felt right. It felt like a beginning.
They lay there together, tangled in the sheets, the plug still settled inside Kan, a constant reminder of what they'd shared. The night was quiet around them, the city's hum a distant lullaby.
"Phra Chan's collar," Kan murmured. "It feels different now. When I wear it, I feel like I'm the person I was always meant to be."
Rei's lips pressed against Kan's forehead. "You're already that person, Kan. You always were. I just helped you see it."
Kan's eyes fell closed, exhaustion finally claiming him. But before sleep took him, he had one final thought—a fragile, secret hope that he tucked away in the deepest part of his heart.
Maybe someday. Maybe someday I really could.
He didn't know if Rei could sense it, but as he drifted off, he felt Rei's hand settle on his belly, a possessiveness that was both grounding and thrilling. And in that moment, everything felt possible.