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“What’d you get?” Serizawa peered into his and Reigen’s bedroom, seeing Reigen opening a delivery box on their bed.
Clearly, he hadn’t intended for Serizawa to catch him in the act, as Reigen’s eyes went wide and then darted away as a nervous smile spread across his face.
“Ah. Well. Something for us.”
“Oh,” Serizawa smiled, a delight warming his chest.
Usually when Reigen said that, he was talking about something for the bedroom. The last time he bought something, it was a pair of cute fuzzy handcuffs: bondage had been something Reigen wanted to try out. Even though they were cute on him, apparently he didn’t like how the fuzz felt and ended up casting them into the closet, never to be seen again.
He walked over, pushing Reigen’s gaze further away until he sat down next to him, peering down into the box. Shyly, Reigen gently nudged aside the black paper wrapping and lifted out…
“Oh, holy shit.” Serizawa couldn’t help the words from coming out.
The packaging was vibrant, a deep red background sparkled with flashy starburst advertisements that strangely felt very Reigen: “Satisfy ANY partner!” “TEN inches of pure trouble!” “NOT for the faint of heart!”
His chest fluttered, feeling particularly faint of heart. Not just from the advertising—in Reigen’s hand was a dildo that seemed ready to burst out of its own casing: the very plastic around it seemed tight and thin, only making the toy seem larger. Its girth was unlike anything he or Reigen had brought into their bedroom—could he even wrap his fingers all the way around it? Just where does he think that’s going?
“Taka, are, uh, are you sure?” Serizawa balked, his cheeks warming. “I mean- no offense, but I haven’t seen you take anything bigger than me.”
“Oh,” Reigen smirked. “This is for you.”
His heart sank, freezing him in place. The toy seemed to be making eye contact with him.
“Huh?”
“Well, you see-” Reigen’s finger pointed out the thin, flared base. “It’s made to be able to go in a strap. So I thought it’d be fun to try out. Right, Katsuya?”
For him? Of course, they’ve tried stuff out before, but… the biggest toy Reigen’s used was probably five or six inches? Just what was he thinking with ten? Couldn’t they have worked their way up? Just looking at that thing had him feeling particularly small, there was no way it was going to fit, it’s impossible-
“Katsuya?” Reigen snapped his fingers. “You there?”
“Uh- yeah, yeah, I-”
“You wanna try it out?”
He jolted, the bed creaking under him. “Wh- now!?”
“No,” Reigen snickered. “But, uh, tonight?”
“Uh- sure.”
Reigen stood up, leaving the… package on the bed and giving Serizawa’s shoulder a firm pat. “Alright, looking forward to it.”
Serizawa swallowed hard, trying to calm himself. “S-sure.”
Deep breaths. It’d be fine.
“Ah…”
Serizawa pressed his cheek against the pillow beneath him as Reigen’s fingers nestled inside him, prodding him, stretching him.
“Theeeere you go, good boy,” Reigen purred, gently rocking the base of his fingers against Serizawa’s ass and drawing out an embarrassed whine from the praise.
Reigen always was so good with his fingers when it came to prepping him: the way he’d gently slide in and out, the way he pushed against Serizawa’s walls, the way he knew when to curl just right…
“Mgh!”
Reigen chuckled. “Yeah, there it is.” He gave a quick peck to Serizawa’s pursed lips, leaning his fingers further against the man’s prostate.
Suddenly, Reigen’s other hand wrapped around Serizawa’s cock, holding it firmly and kneading the head to draw out a deep, guttural moan, forcing Serizawa to turn his head to bury his noises into the pillow beneath him.
“You’re so relaxed back here,” Reigen cooed. He always had something to say during sex, though it was distracting at times. “You think you’re ready?”
Serizawa's heart sank a little as he felt something gently nudge his inner thigh. He opened his eyes to look down instinctively, inadvertently making eye contact with a very eager Reigen. It wasn't like he'd never taken anything up his ass before— that harness definitely got some use —but Reigen seemed almost terrifyingly excited to shove some massive, world-shattering weapon inside him.
Apparently he'd hesitated too much. Reigen’s expression softened, his dominance fading. “You alright? Do you not want to?”
“I… I'm just- nervous.”
“I mean- it isn't every day you take a ten inch dick. Unless you want to, that is.” Reigen laughed before mellowing back down again. “Plus, you don't have to take all of it if you can't, y'know, I can just- stop midway, or something, if that's more comfortable.”
Those fingers were moving again, slow and soothing. “You tell me to stop, I'll stop.”
Serizawa slowly let go of a shuddering breath. “Alright.”
“Yeah?”
“Yeah, just- go slow.”
“Mhmmm,” Reigen purred, pressing a kiss to Serizawa’s neck as he slowly drew his fingers out. “Of course I will. Gotta be gentle here.”
He heard a cap pop and then soft, slick noises between his legs. He opened his eyes to watch as Reigen spread a copious amount of lube on his strap. It was almost menacing how it glistened in the dim light, so close to his body and ready to pierce him. He could feel his heart pound, despite his dick staying just as hard.
As Reigen lifted his thigh and slid his hips closer, Serizawa clenched his eyes shut, feeling that toy tease his entrance, rubbing in soft, slow circles that made his thighs quiver. The fingering had him so sensitive already, he couldn’t imagine what it’d feel like when Reigen finally pushed inside.
“You ready?”
He pursed his lips and gave a fast nod.
From there, Reigen pushed in: he was so slow, so gentle, it made Serizawa’s shoulders tremble as the head finally popped in past that ring-
“Aah…” Serizawa tipped his head back, panting and trying to control his whimpering.
“Attaboy, there you go,” Reigen cooed, giving Serizawa’s cock slow pumps, dragging his hand up and down like he had all the time in the world. “Nice and slow.”
He clenched his jaw and moaned softly as Reigen gently pushed inward. The girth was unlike anything he’d ever taken, making him feel more full than he had in his entire life. He could feel that toy forcing a pressure inside him with its mere presence, stretching his insides and rubbing against his prostate as each centimeter entered him.
Reigen had stopped once a decent size had made its way in. He could feel his cock throbbing, his hole clenching slightly around the toy to try and adjust to its size.
“How’s that? You feeling good?” Reigen’s hand slid down to cup his balls, those delicate fingers pressing into his perineum.
“Oh- oh god-”
He couldn’t help but fall apart at Reigen’s touch, the way he rolled his balls in his warm hand, the way he ran his fingers all the way from his ass to the base of his cock to squeeze it softly-
“You want more?”
“Yes,” Serizawa groaned with a gasp. “Yes, yes .”
That toy was moving again, sliding even deeper and re-establishing that feeling of pressure. It felt like it was getting bigger the deeper he went, even though he knew that wasn’t the case. It pushed on his prostate wonderfully, the stretch getting more and more tolerable the longer it was in. He could feel his body trembling, his breath coming quicker and hotter.
“You’re doing so good,” Reigen purred. “That’s almost all of it, you think you can take the rest?”
It felt hard to get enough breath to even make words; “Yes,” was all he could gasp out.
When Reigen pushed the last few inches in, it felt like any composure he had was forcibly shoved out of his body. The rest of the toy was manageable, comfortable even. Now, with Reigen’s hips pressed flush against his own, all he could do was pant and listen to the hammering of his heart in his own ears. Any more than this, and he felt he could explode.
“God, you’re so pretty,” Reigen murmured, leaning down to dot kisses along Serizawa’s neck, gnawing softly on his carotid to make him whimper. His free hand was sliding up Serizawa's stomach, combing through his chest hair to settle on one of his pecs, squeezing it. “Just let me know when I can move.”
Serizawa blearily opened his eyes, staring past the ceiling as Reigen's kisses and petting brought his heart rate down enough to get a full breath in. He felt so full, more full than he'd ever felt in his life. Part of his heart was scared to let Reigen start thrusting, that the pleasure would be too much.
Another kiss, long and gentle against his jaw. Reigen's lubed hand slowly wrapped around his dick, squeezing softly and running his thumb against Serizawa's tip.
Serizawa closed his eyes again and let his head fall to the side, whining. “You can move. Go slow…”
“Of course,” Reigen purred, dragging his hips back. Even at such a slow pace, having each inch of his insides rubbed again was nothing short of overwhelming.
“Nnngh…” he groaned, his jaw clenching.
“Too fast?”
He just shook his head, panting. Reigen chuckled at that, continuing to draw out— Jesus Christ, it was long —until only the tip remained inside his ass.
“Ready?”
A quick nod.
Slightly faster this time, Reigen pushed in. The combination of that massive cock entering him and the pressure it created inside his abdomen made him feel weak.
“Please, please,” he gasped.
“You're taking it so well,” Reigen cooed, lust dripping off his voice. “And you were so scared before. I knew you'd be good with it, you're so good at taking dick.”
He wrapped an arm around Serizawa's thigh, leaning forward and pressing it into his chest as he bottomed out. “Bet you could take more than this, I wanna see what that ass is capable of.”
At this point, more sounded like pure bliss.
“Please,” he breathed again.
Reigen simply shushed him, soft and gentle. “Calm down, honey, I got you. Don't be so greedy, you'll hurt yourself.”
Serizawa groaned as Reigen made a couple quicker, short thrusts, sending a deep warmth coursing through his body as each and every inch of that cock pushed on his prostate. The pressure was so much, but so good, like something was building deep underneath his dick. He could feel himself dripping, the warmth trickling onto his belly bit by bit.
He tipped his head back, moaning openly as Reigen's hand worked its way up and down on his dick, moving with a familiar muscle memory, twisting ever so slightly on the way down, squeezing gently on the way up. They'd barely started, but he already felt like he was about to cum; Reigen was starting to fold him in half as those thrusts became longer, harder, making that knot inside his stomach blossom. The first time they did this, it felt like he had to pee; apparently, that's a natural feeling, and one he came to be familiar with and enjoy deeply.
“Taka,” he groaned between whimpers. “Please, I- I'm close-”
Reigen didn't say anything that time, only sped up his movements. He wasn't hitting as deep, but wherever he was hitting kept making that pressure build and build, and-
He felt something warm touch his belly; he opened his eyes slightly in confusion, he didn't feel any bit of an orgasm, how-
“Oh, holy shit,” Reigen breathed out, his hand stilling on Serizawa's dick.
A pervasive shame suddenly spread up into his throat as the realization hit: he managed to piss himself. The worst part of all, it felt really good. Reigen hadn't stopped thrusting, and each thrust coaxed out more and more, sending it dripping down his sides, hitting the bedsheets.
He covered his face with his arms, trying to hide his embarrassment.
“Ah- ah- Taka-”
“God, you really like this, huh?” Reigen sounded out of breath, more worked up than Serizawa had seen him before. “You're such a pervert, Katsuya.”
A strangled whimper fled his throat. “I- I'm not- AH-”
Reigen's hand was suddenly pumping his dick again at a feverish pace, trying to milk out anything he could. “You're so fucking cute- fuck, Katsuya, you're such a good slut. You look like such a mess, I wish you could look like this all the time.”
That pressure hadn't left his belly, only intensifying as words kept falling from Reigen's mouth. “You're so cute when you're embarrassed- you're ashamed? Yeah? Ashamed you pissed yourself? Seems you really like it, Katsuya-kun.”
“Taka, please, please-”
“You gonna cum?” Reigen's nails were digging into his thigh as he pressed him further down, restricting his air with his own weight.
“I- I- AAH-”
Serizawa threw his head back, his legs shaking as cum shot across his belly, hitting his neck. Each pulse of his cock made him moan, nearly shouting in bliss; Reigen slowed his pace, gently kneading his prostate to draw out his orgasm.
“Please- please- I can't-”
Reigen slowed down further, dragging down to a stop as Serizawa's cock gave its final aftershock twitches. All he could do was lay there, trying to catch his breath and slow down his racing heart.
“God, you're such a mess right now,” Reigen murmured, dragging a finger up his belly to mingle the fluids collecting on him. “Didn't think you had it in you.”
Serizawa opened his eyes just enough to pitifully look at Reigen in a mixture of embarrassment and post-sex ecstasy.
Reigen leaned forward, gently pressing a kiss to Serizawa's nose. “Guess we'll just have to put a towel down next time.”