Thread by @murcielagoAO3

#miyacest, alpha!Atsumu, omega!Osamu

Osamu grows up big and broad, while Atsumu's leaner and softer and slightly shorter, like a coyote to Osamu's wolf, both of them strong and sexy and nearly identical but Osamu can put one big paw on Atsumu and hold him down like an annoyed

papa with a pup, scolding Atsumu when he's acting up. Osamu's got the nurturing traits though, ruling the home and managing the meals and the chores with a dripping masculinity that makes Atsumu crazy in the best ways. Atsumu's the breadwinner but he's kind of a pampered princess

whining for Osamu to wash his hair while he's having his bath. Osamu doesn't mind, doting on him in this and many other ways, especially since he knows a single shampoo will loosen all of Atsumu's tangled complexes until all that's left is a singular lust.

Atsumu's got a sharpness that Osamu craves, all bones and sinew and muscles with lean power that can knock Osamu right on his ass despite his bulk. All Atsumu has to do is grab hold of Osamu's jaw and lock their eyes, flashing his long tongue that licks along the rows of

pointed teeth within his feral smile, and Osamu's nostrils flare, body producing slick as he takes in his twin's unique, intoxicating scent.

"Gonna breed me?" Osamu taunts, lifting his chin.

"Ya want that 'Samu? Think I should?" Atsumu cocks his head.

And fuck fuck /fuck/

the thought of maybe /not/ getting that knot tears a growl right up Osamu's throat because he wants it, he /needs/ it, it's /his/ goddamn it, and he'll fucking take it for himself if he has to--!

He lunges at Atsumu, but his brother's wily and turns out of his grasp so quick Osamu's fingers can't grab hold of him, dodging all over until Osamu's huffing and growling like a grizzly bear, tearing his clothing off because his whole body's so fucking hot, he's burning up.

His scent is so strong it's verging on rabid, but his brother's scent is even stronger and Osamu's knees start shaking. Atsumu taunts him from their bedroom, rolling in the bedding and shaping it into a messy nest. Osamu staggers over to it and Atsumu snatches his hand and pulls

him right into it, toppling Osamu like a colossal and then covering every inch of him with his body and lips and hands and kissing him deep and strong, dipping fingers between Osamu's thighs and into his slicked hole. Osamu writhes and his body opens for Atsumu, so eager, ready

for his twin's dick to mess him up even more. Atsumu draws wet fingers up Osamu's taint to jerk him off, his talented hand squeezing Osamu's fat dick with every pull. Osamu pulls Atsumu onto him and bites the scent gland on his neck--Atsumu bucks and growls out a string of curses

as he hurries to line up his cock and then plunge it into Osamu's ass all the way in one big thrust.

Osamu nearly comes from just that--Atsumu fills him so full, so completely his heart hurts.

Atsumu pounds him until Osamu's pecs jiggle, but he doesn't care, just groans with

every slap of flesh and holds his brother tight between his legs and says, "Gimme, gimme, gimme..." over and over and Atsumu's hands shift to press so gently into his lower belly and Osamu cries out because they both want this so badly and it's time and fuck, fuck, there's

the knot he wants just knocking on his rim, teasing, and Osamu breathes "'Tsumu-Tsumu-Tsumu-Tsumu!"

Atsumu growls and pushes his shoulders under Osamu's knees and that angle is /perfect/ and Osamu keens, and Atsumu keeps pistoning into him until Osamu thrashes and comes so hard

he can't suck in any air--

Then Atsumu's knot pops inside him and Atsumu grinds his whole length so deep Osamu's dick spurts more come onto his belly, and then Atsumu grits his teeth and /snarls/ as his climax rushes through him, cock twitching with each spurt, all of him

shivering from the unbearable pleasure of his balls emptying into Osamu, filling him so incredibly full. Osamu pulls Atsumu into a kiss, relishing the feel of his brother's jerking hips that signal his orgasm is still going, and going, and going, giving Osamu everything he needs.

Three months later, Osamu's bump is just starting to show, and Atsumu can't stop touching it, hugging Osamu from behind and rubbing his protective hands under Osamu's shirt.

"I bred ya good, Samu," Atsumu hums into Osamu's shoulder, fingers interlocking across Osamu's stomach.

Osamu snorts. "Bout time," he teases. He turns his head and Atsumu gives him a lingering kiss.

"Looks damn good on ya." Atsumu nuzzles into the side of Osamu's neck. "Yer so big everywhere, like a mountain of a man, but this is our little pup, right here."

Osamu turns in Atsumu's arms, and smirks. "Yep. So he better take after me instead of yer puny ass."

Atsumu splutters in offense, but Osamu laughs and distracts him with a kiss. "Just kiddin'."

💖

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