Overse where it's expected and preferred for teen siblings or cousins to take care of each other's physical needs in puberty when their secondary genders present.
Heat/rut in adults can be managed by medication or one's mate,
but prescribing medication to growing youths is considered inhumane, as would attempting to take a mate before the right emotional maturity has been reached, which usually isn't until the early 20s where dating and finding a happy, healthy love bond with a mate is appropriate.
Teenagers just aren't equipped to handle what it means to be someone's life partner, and lack the skills to find and recognize their match. Puberty hormones are part of it, making teens irrational and needy when taken over by their heat/rut, which has no predictable schedule.
Who better to help out during that period than a sibling near the same age? There's a loving bond between siblings even in times when they don't /like/ each other that much, that makes them well suited to be there for each other in those vulnerable times, no matter what secondary
gender they are.
Alpha sisters can help their alpha siblings through their ruts, teach them how to knot and how to control their fangs, scruff them the first few times they fuck until the newly presented alpha learns how not to be such an animal that they irrevocably harm
whoever they get under them.
Omega brothers can help their omega siblings ride out their heats even without access to a knot, teach them how to manage the constant gush of slick by hydrating between orgasms from tribbing and double dildos and if they're really desperate, show
them how to take five fingers up to their knuckle ridge to simulate a knot enough to trigger their heat's end.
Siblings with opposite secondary genders have it a bit harder. Especially /twins/.
Neither knows what's going on or what to do that first time, and their scents are so potent they almost always trigger their sibling into their heat/rut at the same time. Once they start, there's no stopping them, both blindly chasing pleasure and relief on pure selfish instinct.
Without warning, Atsumu goes into heat after school in the gym during volleyball practice. When he collapses to his knees, everyone rushes to see what's wrong, only for Osamu to roar so loud it echoes off the gym walls and ceiling, startling everyone into submission except Kita.
Osamu lunges for his brother, pinning him to the hardwood floor under his hands and knees and snarling his warnings to the rest. Kita gestures them all to move back slowly and steadily, giving Osamu room to focus on Atsumu. Their combined stink starts filling the gym and Kita
gets everyone out before any other team members can react to the twins' pheromones and succumb. He locks the Miya twins inside.
Not that the twins notice or care about anything or anyone else once they're fully overcome with instinctive desires that /must/ be sated.
Atsumu's breath comes out in hot pants, back arching and hips in the air, shorts and thighs already soaked with slick. Osamu rips Atsumu's uniform shirt off with teeth and brute strength, nosing along Atsumu's neck, into his armpits, licking up his sweat and growling with lust.
He yanks Atsumu's shorts down and then off, spreading his cheeks and burying his nose and mouth between them, huffing the scent of his brother's slick and scooping it into his mouth with his hot tongue, moaning in bliss. Atsumu bucks, crying out and pressing into Osamu's face.
Osamu works his tongue deep, swallowing sweet slick until he's drunk on it, proud of the way Atsumu thrashes throughout. He rumbles and digs fingers into Atsumu's hips until he gasps for air - his cock's so hard and full of blood he's dizzy. It hurts but he knows what he needs.
Osamu pushes a hand between Atsumu's shoulder blades so he's completely face down, keeping Atsumu's ass presented. He shoves down the cloth constricting his cock to free it, dripping and turgid between his legs. Atsumu whimpers, trails of slick leaking down his inner thighs.
His thumbs pull Atsumu's cheeks apart, hole glistening, and buries his cock all the way in a single, powerful thrust.
Atsumu wails, jerking like he's been electrocuted until the sound dies out into a wordless, silent scream. He's so tight Osamu shudders, grimacing, teeth
clenched on a hissing growl. He pulls out smoothly thanks to Atsumu's steady flow of slick, and fucks back in with all his strength, knocking Atsumu a few inches forward on the gym floor.
Atsumu yips, groaning, hands clenched into fists. Osamu rams him again, and again,
woozy from the incredible pleasure wracking through his limbs. His face and chest are hot--too hot--and he rips off his shirt and mounts Atsumu fully, hands beside his shoulders and knees and body pinning Atsumu in place so he can fuck him like a jackhammer, no finesse, all lust.
Osamu's knot inflates and he's eager for it fit, to lock them together for the release building in his sack, drawing up into his loins. His knot catches on Atsumu's rim and his brother squirms and whines like he's in pain, like he /loves/ it, like he never wants this to end.
Osamu pants into Atsumu's nape, fangs elongating and pricking skin. Atsumu rears back at the feel of Osamu's fangs ready to bite and Osamu growls, so aroused, so close, his knot pushing further and further until it finally pops in. Atsumu screams, throat bared, body twitching.
Osamu grinds deep, eyes fluttering closed from the unique ecstasy of his twin's rim clenching around his fully swollen knot. His glutes tighten, body taut and on the edge--cock twitching as the first spurts of his orgasm rip through him.
Both twins break into a howl, bodies
locked together, shuddering in shared orgasm, Osamu's extending long past the point of Atsumu's collapse. He growls and huffs, twitching through the onslaught of pleasure, sinking his teeth into Atsumu's nape over and over, bucking from the incredible load pouring into his omega.
Atsumu sobs beneath him, spent and crushed under Osamu's weight. It's all Osamu can do to lay on top of him and whine, licking the blood from his bite marks, hips jerking and cock still spilling his alpha milk in bursts of euphoria that hitch his breath for several minutes, knot
still hard as a fist even when the final dribbles of come leave his sensitive cock, sheathed and warmed by Atsumu's inner walls.
Neither of them are able to speak, rendered completely incoherent by their first mating. There's a single moment of tenderness, fingers
interlocking.
Then the mating urge sparks again, Osamu's knot deflating but his cock still erect and his mind possessed by the imperative to /breed/ and /mark/, which is exactly what he does until both he and Atsumu pass out in a puddle of slick and cum right there in the gym.
It gets better.
They learn each other in increments, learn how to make it really good for each other instead of the one-sided heat/rut crazed brain fog that has them taking without giving until they can attain some level of control.
The unpredictable heats and ruts get easier, take less time to work through once they get how to truly satisfy each other, crack the code for assuaging the drive to mate or to get bred.
Their parents are glad for their progress, telling them how proud they are for learning to manage their heats and ruts so well. It'll help so much when they're older and start dating and looking for a mate to settle down with to build a happy life
Both twins agree, as they're expected to. That's how this is supposed to work - what they learn about managing their needs now as teens in puberty will help them have good, satisfying sex lives with their future mates.
Deep down, however, the idea of mating with anyone else
makes them nauseous with anxiety.
They're seniors now and preparing for graduation. Atsumu's body craves Osamu's even outside of his heat. His heart wants Osamu, and nobody else. He can't even imagine another alpha ever touching him or holding him at night.
"Dont' cry," Osamu whispers, spooning Atsumu under the covers and reaching to brush the tears from his cheek. "It's the same for me. Yer my omega. My /mate/."
"But yer mark always fades, Samu. I hate it."
"So I'll mark ya again. As many times as it takes," he insists.
Atsumu catches his hand, bringing Osamu's fingers to his mouth and kissing each knuckle. "Promise?"
"Swear to ya, Tsumu, yer the only one fer me. Even if I gotta mark ya a million times, I'll do it."
Atsumu nods, biting back a sob. "Okay, Samu. I believe ya."
"Good." Osamu nips Atsumu's ear, hugging him tighter. "Leave it to me. Got a plan an' everythin's gonna be just perfect."
Years later, the twins get married in a beautiful double-wedding to the happiness and delight of all their friends and relatives. Osamu and Sakusa move into a newly built house right next door to Komori and Atsumu, the four close friends (and relatives) living happily ever after.
If they also happen to have keys to each other's houses and swap spouses in their beds each night, and one day might raise their pups together, that's nobody's business but their own.
Captain Atsumu and First Officer Osamu command a Federation science vessel on expedition through an unexplored quadrant of space.
After surveying the surface of an alien planet, a transporter malfunction creates a duplicate of Osamu.
There's a time delay before the second Osamu appears, so it's not clear to anyone what's happened at first. Osamu seems tired and a bit disoriented, which is understandable after all the away trips to the surface, so Atsumu doesn't suspect anything right away.
They have separate quarters but an adjoining door, since they're brothers and all. Atsumu checks on Osamu that night when his shift on the bridge is over, thinking he'll get him some pudding and tuck him in. Osamu's worked so hard down on the planet and he deserves some rest.
#miyacest#nsfw fraternal #twincest brainrot 💖
cw: oral sex, piv sex, underage (middle to hs miyas), she/he pronouns so you can imagine whoever you want ✨
(god, fraternal miyacest is just so good??? like you get all the goodness of twincest but then also size difference??)
girls mature faster so she's taller by 5th grade and fills out first, by 7th grade her boobs are envied by all the other girls along with her curving hips and strong legs from volleyball. he's still not much to look at yet, all gangly, but he sure likes what he sees, and she
thrives on the pleading, pining looks he sends her way day and night. she turns him into her pussy hound, gets him under her skirts licking her wet slit whenever she wants because he's thrilled just getting glimpses of her bra, so of course he's going to do anything she wants.
Shouyou and Natsu know to give the twins private time together on their birthday. It's their special tradition, after all.
But this year, for the first time since they were born, they won't be in the same location to celebrate their birthday and the effect this has on both twins is unexpectedly dramatic.
Shouyou tries to appease them. "It's just a day on the calendar. Why not wait until Osamu's back
from his business trip? Postpone for a bit?"
The twins know what Shouyou's saying makes sense. But Shouyou's logic - how he's had to delay a lot of things going back and forth from Brazil so it's normal for him - doesn't quite work on the two of them, who have shared a womb.
#nsfw#miyacest cw: masturbation, tentacle dildo, anal sex
Atsumu half-jokingly mentions one night that it might be fun to have a monster dildo like a tentacle or something to play around with sometimes.
Osamu knows full well that behind the joke, there's a real desire for kink exploration, and damn if he's not into it too.
He finds the most massive tentacle dildo on the web, and orders a custom one with a deep grey base like an octopus, and a pink fleshy color for the S-curved
and knobby insertible end with faux suckers that get smaller at the tip.
It's monstrous all right. /Obscene./ And oh, the thrill of presenting it in a box to Atsumu, watching him unwrap it and then--eyes bulging--turning bright crimson and stuttering, nervous to even pick it up.
Or rather, Tobio's not allowed to enter anyone else's salon, or sit in anyone else's chair but Miwa's.
He goes to her whenever he needs a trim, texts her to set up an appointment right after closing time and she evens out his bangs, takes the length off his neck. Easy peasy.
But that comes after he strips naked and she fastens the slick black smock around his regal neck, sitting him down in the chair by her shampooing sink.
The smock covers his arms, chest, and lap. She tilts his head back into the sink, checking the water temperature on her wrist.
#miyacest fraternal twins, fem!atsumu, puberty things
They're not that different in personality or behavior or even looks until puberty hits and Osamu shoots up four inches in a single summer and Atsumu suffers the unique humiliation of going bra shopping for the first time.
Osamu teases her relentlessly the day they notice her chest has started to change. Unlike flat-chested, scrawny eleven year old Osamu, the tiny mounds under Atsumu's puffy nipples turn the horizontal stripes of her tank top into wavy lines, marking her as /not a boy./
Osamu points and snickers. "Looks like ya stuffed coupl'a grapes in yer shirt!"
Atsumu's mouth falls open, and all she can manage is to turn red and yell at him to "SHUT UP!" through gritted teeth. She can kick him too, she realizes, and she tries, but he blocks and skips away.