Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/2738147.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      M/M
  Fandom:
      Big_Hero_6_(2014)
  Relationship:
      Hiro_Hamada/Tadashi_Hamada
  Character:
      Hiro_Hamada, Tadashi_Hamada
  Additional Tags:
      Omega_Verse, Mating_Cycles/In_Heat, Bonding, Anal_Fingering, Rimming,
      Prostate_Massage, Anal_Sex, Knotting, Biting, Omega_Hiro, Alpha_Tadashi,
      Fluff_and_Smut, Idiots_in_Love, Multiple_Orgasms, Marathon_Sex, Self-
      Lubrication, Dubious_Consent, Unhealthy_Relationships, Sibling_Incest
  Stats:
      Published: 2014-12-08 Words: 4974
****** The Biology of Cinnamon and Honey Vanilla ******
by orphan_account
Summary
     "It's an old evolutionary tactic for omegas to be physically stronger
     and more resilient than all other ranks during their heats, in order
     for them to withstand even the roughest matings and to fend off
     rutting alphas, and Tadashi, desperately trying to keep himself from
     going into a rut, is weaker than his brother for the first time in
     his life."
      
     Tadashi had always believed that he would be a beta.
Notes
     hey look it's the omegaverse fic no one asked for but you're all
     getting anyway
See the end of the work for more notes
Before he presented, Tadashi had always believed that he would be a beta.
Certainly, his eldest, most conservative relatives believed this by his
consistency, his tendency towards logic. He fit the exact portrait of the beta
stereotype: non-aggressive but assertive, highly intelligent, less physically
prominent, and wise beyond his years. In their eyes, he was not domineering and
aggressive as an alpha, nor sweet and loving as an omega, and certainly not as
charismatic as a delta. And while their perceptions on what social ranks truly
meant were certainly flawed, Tadashi himself had been quite aware of the actual
biology of the matter and how well he fit into such stereotypes.
To him, it was clear in the lack of physiological hints that would occur in
other ranks. He'd watched as one by one, his peers showed clear tendencies to
shadow biological attributes and statistical trends  of each of their unique
ranks: Caitlin had not presented until she was in her late twenties, as most
alphas did; physically smaller and weaker than all the rest of his peers, John
had presented as an omega at twelve and found his soulmate at sixteen; and
Alex, like most deltas, was asexual. Gogo, the same age as Tadashi, had yet to
present and felt no stirrings of it, and was most likely to present as an
alpha, while Honey and Wasabi had already presented as betas in the past year,
and Fred had presented as a delta long before he became friends with anyone in
the Nerd Lab.
To Tadashi, it seemed the only possible answer. At twenty-one, around the
common age for betas to present, he hadn't presented yet but could feel the
stirrings of it in his gut, and like the majority of betas, he was queer
(multisexual, to be exact). He was too broad and tall to present as an omega
but was smaller than the average delta, and he'd certainly never felt any
response to the scent of an omega in heat.
So, upon waking on the eve of his twenty-second birthday, he was startled and
disturbed to find the head of his suddenly-much-larger cock swollen and leaking
copious amounts of semen all over his sheets.
Of course, Aunt Cass had thrown him a party (“You should be excited, it's your
first step into true maturity!”) and Hiro had teased him about his incorrect
predictions (“Your nerd skills failed you yet again, nii-chan!”), but his
friends had shared his surprise, agreeing that his presentation as an alpha was
certainly unexpected.
“I was certain you'd be a beta,” Honey had told him cheerfully. “You'd seemed
so sure of it yourself!”
“I thought you'd be a delta before I knew you weren't asexual,” Wasabi had
admitted.
“You're small for an alpha,” Gogo informed him, and Fred had snickered in
agreement.
Certainly, Tadashi cannot quite find that his status as an alpha has changed
much in his life. Of course, he is more than aware now of new limitations, such
as how to avoid going into a rut at the scent of a heat and what detergent is
most effective to wash his sheets in. He still works at the café part-time,
attends all his classes, wears mostly the same clothes, and still coddles Hiro
whenever possible (not that he'd admit that to his ototo, of course.) He still
works for hours in his lab perfecting Baymax, and spends his Friday nights
waiting tables at the cafe and playing Ghibli movies on all the café
televisions.
As much as Tadashi is satisfied with his rank, however, he can’t help but wish
he'd presented as something different. To bond meant to connect two souls
together, was a mark of the strongest relationship one could have, be it out of
romantic love or one of deep friendship, although certainly friendship bonds
were far easier form and much less complicated. As a beta, or even a delta or
omega, he could have bonded romantically with a number of others, had a better
chance at looking for someone to spend his life with. As an alpha, however, he
could bond platonically, but only once romantically, and if it broke, he would
not receive a second chance.
There was only one person Tadashi wanted to spend his life with like that, and
that was Hiro.
It wasn't unheard of for blood relatives to bond—it happened on rare accidents,
typically as platonic bonds, and while romantic bonds weren't exactly smiled
upon, no one tried to break the bond as long as the two were consenting adults.
But Hiro was his brother, his ototo who didn't hear Tadashi whisper his name as
he stroked himself, thought nothing of all the lingering touches, didn't want
his brother the way Tadashi did, and Tadashi knows that Hiro would never want
the kind of bond that he ached so deeply for.
It's not until Hiro presents as an omega that everything changes.
===============================================================================
Hiro stares down at his plate, lower lip jutting out in a pout. It's hot wings,
he tells himself. Aunt Cass' hot wings. You love these. He pokes at one with a
finger, but he can't bring himself to pick it up, let alone eat it.
“Hiro? Are you all right?”
The boy looks up from his dinner plate, still frowning, and meets Tadashi's
worried gaze. “You haven't eaten anything,” Tadashi continues, scooting his
chair closer and placing his palm against his brow. “Are you all right?” His
brow furrows and he hums anxiously. “You're warm.”
Hiro tries not to shudder at the touch and sighs, gently brushing away
Tadashi's hand. “I'm fine,” he says, rolling his eyes at Tadashi's unconvinced
expression. It's just the two of them—Aunt Cass is in New Seoul speaking with
investors looking into her café—so there's no one to help hold the full weight
of Tadashi's coddling at bay. “Look, I'm just not hungry right now. I'll be
fine in a little bit, so just wait, okay?”
Tadashi reaches out and takes Hiro's hand, tugging Hiro to his feet and pulling
him close with a disapproving hum. “Come on, you need to lie down for a bit.”
Hiro burns a brilliant pink and opens his mouth to protest, but Tadashi has
already turned and is dragging Hiro up the stairs and into their room, pushing
the door open and pulling him across their room. He flings back the covers of
Hiro's bed and nudges him toward it, and when Hiro refuses, glaring stubbornly
at his older brother, he picks him up and dumps him onto his mattress.
“Tadashi, will you stop worrying so much?” Hiro says in exasperation, groaning
as his brother pulls the covers up to his chin. He pushes them back down and
sits up, eyes narrowed. “I'm sixteen already, you can stop treating me like a
child.”
“I worry because you're a reckless little shit and because you're my brother,”
Tadashi tells him patiently, pressing Hiro back onto the bed and pushing the
covers back up. “Now lie down and take a nap or I will sit on your legs until
you do.”
“You do that, and I'll kick you off,” Hiro says grumpily, even though they both
know how empty the threat is—besides being a few inches shorter than his
brother, Hiro is also ten pounds lighter and physically weaker.
Tadashi smiles and leans forward to press a soft kiss to Hiro's brow, stroking
his cheek gently with feather-light fingers before he goes to flick the lights
off. Before he leaves, he adds, “I'll check on you in an hour,” and shuts the
door, leaving Hiro in the dark.
Hiro can feel where Tadashi touched him, the spots on his brow and cheek
tingling. He sighs, shifting to his side and letting his eyes slip shut.
He's always loved his brother, even with his overprotective fussing and
hovering, but Hiro had never quite comprehended how much or in what manner, at
least until Tadashi presented as an alpha. He's certain his older brother never
quite noticed all the ways he had changed, from the way the scent of cinnamon
and musk mixed with the clean smell of his aftershave and detergent to the way
his shoulders had broadened just slightly and his hair had become a bit
thicker. However intelligent Tadashi may be, his tendency to be completely
oblivious meant he'd never even consider that he was beautiful enough that
people would stop in the street and stare, never see the starstruck gazes or
hear how people whispered in admiration after holding even the smallest
conversation with him.
Seeing so many captivated people pining away after his newly presented brother
had made him annoyed and jealous. How dare they ignore the perfection that was
his brother, he’d thought, only to beg for his attention as if only now was he
worth their admiration? Even before Tadashi had presented as an alpha, Hiro had
spent enough long hours watching his brother work, captivated simply from the
way he ran a hand through his hair when upset or chewed on the inside of his
cheek when in deep thought. He could spend days talking with Tadashi on any
subject, be it robotics or politics, could tell him anything, and Tadashi would
understand, even if he didn't always agree. No one understood him the way his
brother did, and Hiro liked to think that no one ever would. Hiro loved Tadashi
more than anything else in the world, and as Hiro had realized, in more far
more ways than just as a brother.
It had gotten worse the past few months, Hiro thinks forlornly, and even more
so in the past few weeks. Once upon a time, he would have been content as long
as he could be close with his brother, know that he was safe, but Hiro aches
now, fingers itching to slide into Tadashi's hair and tug him down, wants to
touch him so badly it burns like a physical need. The way Tadashi smiles at him
makes Hiro want to launch himself straight into his brothers arms and kiss him
until the world ended, melt into his touch and never leave.
The irony of it was that Tadashi loved him just as much. Hiro knows Tadashi
would give him the world if that was what he wanted, present him the universe
on a silver platter if he asked, and would strong himself up by the ankles as
long as it meant Hiro would be safe and happy. He just can’t love you the way
you want him to,Hiro thinks miserably.
He falls asleep to these thoughts, and when his brother reenters the room to
check on him, he doesn't wake up.
===============================================================================
The next time Hiro wakes, it's nearly six in the morning, and he hurls himself
into the bathroom, grips the sides of the toilet, and retches into the bowl. It
takes less than thirty seconds for Tadashi appear behind him and murmur gently
in his ear, holding the hair back from his face and stroking his back
soothingly as he gags and shudders, bile burning his throat until there is
nothing left to expel.
He slumps back a half hour later, whimpering slightly, and shivers and pushes
at his brother's chest when Tadashi cups his face and cleans around his mouth
gently. “M'fine,” he protests faintly, flinching away from the damp washcloth
and mumbling incoherently when Tadashi tosses the cloth into the bathtub and
scoops him up into his arms.
“Let's get you back to bed.” Tadashi tucks him back in, kissing his forehead.
“Oh, Hiro, you're burning up,” he murmurs softly, and Hiro flushes, burying his
face in his pillow. “Guess there's no going to school today, then.”
“No. No … I need—” Hiro mumbles. “Class, Tadashi, I need … I can't miss …”
“You have to stay home,” Tadashi admonishes him, tucking him back into bed and
pulling the trashcan close to his bedside. “It's okay, Hiro, just go back to
sleep, okay?”
Hiro grumbles and squirms, then reaches out and tugs weakly at his brother's
shirt. “Get me the work,” he demands, and Tadashi sighs, nuzzling Hiro's cheek.
“I'll go for a little bit and get you notes and homework, but I’m not leaving
until you promise to stay home and sleep. Okay?”
Hiro sighs and nods grudgingly before nuzzling closer to him, inhaling deeply,
and Tadashi looks down at him in amusement and fondness. He strokes his hair
before rising, grabbing several blankets and spreading them over Hiro to keep
him warm. His little brother shivers, whimpering before his soft noises slow
and he grows silent. Tadashi watches as his breathing steadies, heart twinging
oddly in his chest, and goes to get ready for school.
Four hours later, long after Tadashi has left for school and long before
Tadashi promised to return, Hiro is burning.
Every inch of his skin prickles, oversensitive. Even the slightest caress of
cloth against skin, a wayward breeze, sends electric spikes of pleasure up his
spine, and he writhes upon his mattress, gasping and whimpering. His cock
twitches and bobs, drooling precum all over his stomach, but it's his hole that
aches, fluttering and spasming. Hiro has never felt so empty, never needed to
be filled, made complete and whole, and it hurts.
He only has enough comprehension in him left to understand that he is
presenting, obviously as an omega, and knows that this, his first heat, will
last at least a week, two without a partner to spend it with. Hiro exhales
shakily, hands slipping down to trace the quivering, newly slick pucker, and
slides one, two, three fingers in with ease. He sobs as the burning worsens,
and jerks his fingers in and out, moaning at the filthy wet squelches; it only
takes a single brush to his prostate for him to arch high off the bed with a
cry, stripes of cum shooting high and splattering all across his chest and
stomach.
Despite his age and already wildly imbalanced hormones, Hiro is unused to
coming this quickly, and certainly unfamiliar with this nonexistent refractory
period. It's unsurprising—most omegas lack one regardless of their sex
organs—but no less frustrating, and Hiro's head falls back as he   begins
again.
His fingers seem to have gained a mind of their own—they grind mercilessly
against the spongy flesh, and he shoves another finger in, weeping at the lack
of relief. There should be a knot there, pressing in all the right places to
relieve the heat bit by bit, but the first heat is always the strongest, it’s
obviously impossible for him to knot himself, and Hiro can barely stand up
straight, let alone find anyone to take pity on him and give him their knot.
It's worse with the faint scent of alpha lingering in the room, traces of his
absent brother that only aggravates his heat. Any omega has the unmatched power
to bond regardless of rank and break each through sheer willpower, but bonds
with alphas are the strongest and are nearly impossible to break, given that
alphas only bond once in their lifetime. Hiro wants that connection with
Tadashi more than anything, wants the closest thing he can ever have to a
promise that lasts a lifetime, and begins to cry for fingers that are not his
own, breathing in the sharp, cinnamon scent of alpha.
===============================================================================
 It's almost noon in late May—the perfect weather for eating lunch outside and
stargazing—and the hydrangeas are beginning to bloom. The streets blur powdery
blue, soft violet, pale yellow, and rich pink as he zooms past on his scooter.
Usually he stays at school to eat, but Tadashi's been gone too long and Hiro is
home all alone, suffering from what looks to Tadashi like a nasty stomach bug.
He parks his scooter in the garage and pulls off his helmet, setting it on the
seat and humming in discontent. Even when sick, Hiro still drags himself down
to the garage to build and tinker. Many times before, Tadashi has found Hiro
feverishly typing away on three computers at once, snot dripping from his nose
and swallowed up by an enormous pile of blankets.
If he isn't here, he must be throwing up in the bathroom again, Tadashi thinks,
and hurries inside. “Hiro? I'm home,” he calls, and makes his way up the
stairs.
He's halfway up when the scent hits him like a wall, and Tadashi has to cling
to the rail for support, inhaling sharply at the sweet, musky scent that spills
over every surface and pushes through the cracks in the door. His head
immediately goes dizzy, and he chokes at the snarl that bursts from his throat,
hand flying up to block his nose.
“Gods,” he growls, and it's the strongest, loveliest heat he's every smelled,
the taste of honey and vanilla with just a hint of mint and ginseng tangible on
his tongue. It smells like Hiro, and Tadashi forces himself not to lower his
hand and simply inhale. He can feel his pupils dilate with lust and moans, low
and rumbling.
He makes it to the top of the stairs and has to grab the rail again, this time
because the last, quickly dwindling remainder of his sanity is afraid of what
will happen if he lets go. More than anything, he knows he needs to flee, to
get far, far away from his brother, but he can't bring himself to leave Hiro to
go through this alone.
Before he can decide, the door to their room creaks open slowly, and Tadashi
bares his teeth and snarls as the scent doubles in strength. Hiro pokes his
head out, and Tadashi wants to pick him up and hold him and never let him go at
the sight of him. He's bundled himself up in all his blankets, with only his
eyes, feet, and a few tufts of hair visible. His eyes are wide and glassy, and
he stumbles from the doorway towards Tadashi with a whimper.
He face-plants into Tadashi's chest and looks up at him with desperate eyes,
tugging on his shirt. “Nii-tan,” Hiro slurs, half-drunk with arousal, and
Tadashi shudders, hands tightly clutching  his little brother's waist. “You
were gone so long …”
“Hiro,” Tadashi hisses, and his little brother moans, needy and begging.
Tadashi can feel Hiro's legs trembling, as if he can barely hold himself up,
and Tadashi finds himself shaking with the effort to keep himself from sinking
to his knees to taste the sticky fluid steadily leaking down Hiro's bare legs.
He pulls Hiro back into their room and tosses him onto his bed, trying to nudge
him under his covers, but Hiro keeps slithering back to Tadashi, rubbing his
nose along his neck and purring at his pulse point. Tadashi stills reflexively,
and he yelps as he feels Hiro's mouth part and sharp teeth brush his skin.
“Hiro, no.” Tadashi tries to twist out of his little brother's grip, but Hiro
keens and flops himself on top of his surprised brother, knocking him back and
burbling as he wriggles around on top of him.
It's an old evolutionary tactic for omegas to be physically stronger and more
resilient than all other ranks during their heats, in order for them to
withstand even the roughest matings and to fend off rutting alphas, and
Tadashi, desperately trying to keep himself from going into a rut, is weaker
than his brother for the first time in his life.
And Gods, he wants him so badly.
“Tadashi,” Hiro pleads, one spasming hand flying up to grasp at his brother's
wrist. “Haa—I need—I need—”
“Hiro,” Tadashi says raggedly, and when his little brother sobs and grinds down
against him, he can feel the wet, silk-soft, trembling pucker twitching right
above his cock.
He's soaking.
The last of Tadashi's control snaps, and he flips them over, slamming Hiro
face-down against the bed and holding him there with a vicious snarl.
Hiro catches sight of his brother's expression, ravenous with hunger and pupils
ringed only by a bright circle of coppery brown, and then he's face down on the
bed, his brother breathing harshly in his ear. He squeaks as a hot tongue
traces the shell of his ear and plunges into it. Three fingers stroke down his
spine and nudge between his cheeks, stretching his hole wide around them as
they thrust inside.
“Nnngh—ahn—!” Tadashi finds his prostate within seconds and takes to rubbing
and scratching lightly against it. “Tadashi, please—ah, ple—hyahh—ahnng …”
“Mine,” Tadashi purrs, rubbing harder, and his little brother wails, arching
desperately into the touch. He rumbles happily, lapping at Hiro's shoulder and
moaning. One hand slips below and tightens around Hiro's cock, preventing him
from coming, and Hiro gives a displeased whine. “Going to clean you up, slip
inside and breed you, give you my knot and fill you with seed—clean you out
with my tongue till you cry—”
“Ta—ah—ah, Tadash—” Hiro shudders and gasps, nerves alight, trying to escape
the relentless prodding, and Tadashi croons, massaging the nub between three
fingers harshly, a slightly sadistic little burble escaping his mouth as he
keeps his other hand clamped too-tight around Hiro's cock. “Ahn—nahhh, haa,
haa~”
“Drink all your sweet little milk from your cock,” Tadashi slurs, “Lick it all
up and swallow you down—”
“Nii-tan, please, let me come,” Hiro sobs, and Tadashi gives a pleased moan,
flipping Hiro onto his back and sliding down between his legs, swallowing Hiro
to the root and pinching his prostate between jerking fingers.
Hiro comes with a cry, arching up into the tight, wet heat of his older
brother's mouth, and Tadashi moans at the taste, drinking him down hungrily and
mercilessly milking his prick until his little brother stops tugging
frantically on his hair and falls limp.
He flips him onto his stomach again and pulls Hiro's hips up as high as they
can rest, spreading the soft globes of his arse and pressing wet, sloppy kisses
all along the crease. Hiro gasps as Tadashi's tongue, warm and wet, flicks over
his hole once, twice, and again. Hiro jerks and squeaks, shuddering as the
muscle traces around his rim before plunging in.
“Hya—!”Tadashi spears him open with his tongue, humming in pleasure at the
taste, and clamps his lips around the hole. Hiro realizes only too late what
his brother is doing before Tadashi sucks hard against his pucker, drinking in
the heat-slick spilling from the hole. “Ta—Tadashi, w-wait, please, w—hhaahhn,
yah, ahh!”
His brother groans and tightens his grip, trying to keep a frantically sobbing
Hiro from escaping the sensation. Hiro's limbs go limp, and Tadashi keeps him
propped up, lapping at the honey-vanilla slick and nipping at the spasming rim
before he dives in again.
“N-need to—c-come—” Hiro begs. “N-need—ah, ah—Nii-tan, ple—hhaaah~”
Tadashi pulls away slowly, licking the slick that soaks his mouth and chin, and
takes himself in hand, tracing his little brother's trembling rim with the head
of his cock. Hiro makes an unhappy noise as Tadashi hovers, just the tip of his
cock rubbing up against the loose, slick little pucker, and arches up in an
attempt to get him inside. Tadashi spreads his legs on either side of Hiro's,
drinking in the sight with a vicious, predatory delight, and plunges in without
warning.
Hiro's eyes shoot wide open, and he bleats as Tadashi pushes in deeper and
deeper. He can feel every vein, every crease, could memorize the surface of his
brother's cock just from this. It feels perfect: the girth is just wide enough
to stretch him obscenely, pressing deep and hot, and Hiro shudders and keens,
arching his back and mewling when his brother finally slides in to the root.
Tadashi pauses for a second, panting, and pulls out until the tip of his prick
is just barely popping out of the rim before he slams home, grinding the head
of his cock right along Hiro's puffy, oversensitive prostate. Hiro gasps and
screams, precum exploding from his prick in a constant, thick, drooling mess,
legs trembling with the effort of holding himself up.
“Mine,” Tadashi moans, shoving in deep and gripping Hiro's hips tightly.
“Hiro,you're so tight,” he slurs, and slips his thumbs in to join his cock,
tugging at his rim and angling himself to ram directly against his little
brother's sweet spot. Hiro wails, writhing and frantically pleading, and
Tadashi groans as Hiro squeezes around his cock tightly, pressing close and
trailing soft, wet kisses up Hiro's neck.
“Yours,” Hiro sobs, “Yours, yours—ah—please—”
Tadashi is relentless, stabbing thrusts hard and fast, pulls out far and
plunges in deep only to slam cruelly against Hiro's prostate, and his little
brother buries his face in the sheets, stifling his desperate cries, unable to
do anything more than take it.
It seems like several long, glorious hours of Tadashi fucking into him, milking
one orgasm out of him after the other. The sheets are damp and sticky with
slowly cooling cum, and Hiro's skin is littered with angry red bite marks, when
his brother's thrust grow erratic and forceful. Hiro can feel his cock
quivering inside of him, can feel the head beginning to expand, and clenches
down instinctively on it, desperate for it.
“Tadashi,”Hiro begs, and Tadashi bites down on his neck hard as he bottoms out,
knot expanding right over his little brother's prostate and spilling hot and
thick inside of him, trapped deep by the head of his cock. A sharp, gasping cry
flies from Hiro's throat, and he paints the sheets below him for the ninth
time, going limp with relief and satisfaction.
It's impossible to impregnate an omega in their first heat, but Hiro can feel
something warm and solid settle in his chest—a bond—before he passes out from
exhaustion, his heat still thrumming in his veins.
===============================================================================
 He wakes with a start to find himself bundled up in countless blankets and
fresh sheets. The sky has faded to a soft, pastel sunset with the pinpricks of
distant stars just beginning to scatter behind the clouds, complementing the
sound of a mourning dove warbling oddly somewhere outside his window.
His alpha is sitting on the floor by his bed, staring forlornly at the clock on
the far wall in silence. A washcloth lies on the floor beside him, and Hiro
runs his fingers absently along the clean, dry skin of his thighs. Hiro blushes
as he sees the scattered, bruising marks littering Tadashi's skin; he's
distinctly sure that Tadashi was the one who did the most rough handling, so to
see these that he himself had made so unconsciously is more than a little
daunting.
For a moment, the two say nothing, and then Hiro crawls to the side of the bed,
touching his brother's shoulder tentatively. “Nii-chan?”
Tadashi doesn't move, but closes his eyes, exhaling shakily. “Hiro, I'm so
sorry.”
“Tadashi?” A nasty pit begins to form in Hiro's stomach, and he swallows
against the bile rising in his throat. “I don't understand.”
His brother shakes his head, shoulders bowing as he puts his head in his hands.
“I didn't mean for any of this to happen. Hiro—I swear, I promise I'll do
everything to make this okay—”
“You don't … want me?” Hiro's voice cracks, and Tadashi turns to look at him in
surprise. “You don't … want to, to k-keep our bond?”
“Hiro?”
The boy closes his eyes, trying to calm himself down. Of all things, this—this
is worse than anything he had imagined, worse than watching in silence as
Tadashi fell in love, because at least then Tadashi would not have
intentionally rejected him as he was now. He would not have ruined things for
his brother, taken away his one chance at bonding with someone he wanted to
share a life with.
“It's okay,” he says finally, trying to keep his voice from trembling and
knowing he was failing miserably. “I understand, a-and Tadashi, I didn't mean
to—to take anything away from you.” Hiro looks down at his hands, interlocking
his fingers. “Now … now you can't … ever bond again, I mean, I think you can’t,
not that romantic love needs to be sexual, I just—maybe not platonic—look, I'm
really sorry, I just—I-I wanted—” He squeezes his eyes shut. “I wanted you—”
Large, warm hands slide around his waist, and Hiro squeaks. They tug him
forward off the bed, onto Tadashi’s lap, and into one bone-deep kiss, and Hiro
throws his arms around his brother’s neck, kissing him back as the balloon in
his chest swells almost to breaking point. Hiro feels Tadashi’s mouth curve
upwards in a smile, and he slides his hands through Tadashi’s hair, soft noises
spilling from his throat.
“For a child prodigy, you’re a bit slow on the uptake,” Tadashi teases him when
he pulls away, and Hiro makes a face at him, burying his face in his brother’s
shoulder.
“I’m not the one who assumed his brother had no feelings for him whatsoever
after he fucked him into a mattress.”
Tadashi’s cheeks tinge with pink, and he flicks Hiro on the side of the head.
“Language,” he scolds, and Hiro rolls his eyes and laughs.
“You know,” Hiro says hopefully, wriggling slightly, “Since I just presented
and all, I’m technically still in heat for the next week or so.”
Tadashi opens his mouth, probably to say something along the lines of, “I
literally just knotted you, you little shit, your heat isn’t going to come back
in full force for at least twelve hours”, but that is an argument for another
time, and Hiro is already tugging him back onto the bed.
 
End Notes
     and then tadashi becomes addicted to the taste of hiro's omega-slick
     and eats him out whenever he gets the urge (which becomes
     increasingly inconvenient) and eventually hiro and the others have to
     have an intervention and send tadashi to alphas anonymous because
     apparently this problem is not uncommon
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