Author's note: There are elements of Omegaverse I just love (Knotting? Yeah, I am all. over. that). So, of course, I have to tinker with other parts, like the biology and the cultural assumptions, because that's what I do. This fic is the result of a rampaging plotbunny that would not remove its fangs from my leg until I surrendered: what if envelopment, not penetration, were culturally considered the "dominant" act? What follows from that one change?

You would not be reading this story if not for Pat_Is_Fannish, its midwife; Strangegibbon, my much-loved and long-suffering beta; and the encouragement of ancientreader and MildredandBobbin, who assured me I would not be drawn and quartered for it. Probably.

All blunders, mistakes, and lapses in judgement are my own.

Chapter 1: Biology and Destiny

Mycroft was the best and most wonderful brother anywhere, ever, and possibly the best and most wonderful person in the world, genetically related or not. Sherlock did not yet have sufficient data to confirm that so it was still speculation at this point even though he was sure evidence would bear out his thesis eventually. He had a plan to test the theory. It involved a great deal of travel to collect data. Oceanic routes would be most effective for the purpose, obviously.

Mycroft was an omega. Omegas were the best to be. They ran everything and they could go anywhere they wanted and whilst Sherlock did not understand the appeal of copulation and bonding, if one had to participate then surely it was infinitely better to be the one doing the choosing (although participation could likely be circumvented with sufficient willpower. Many things could).

Sherlock was an alpha, but that was probably another of those things stupid people said couldn't be changed when it was just that they were too lazy to do it. Lazy and stupid.

Mycroft was brilliant, properly brilliant, and he never tried to make Sherlock dull or treated him like a weak, pathetic alpha to be sequestered away for his own protection, and Sherlock was going to be just like him and they would be amazing together.

# # #

Puberty was the best thing ever to happen to John.

All through his childhood, alphas had been bigger, stronger, meaner, dominating the sport he wanted to play, shoving and snarling for status. The omegas were told again and again to be patient, to let them have their fun while it lasted. Some of the adults looked at the loud, pushy alphas with something like pity when they said that, but John just gritted his teeth and learned to shove back until the packs knew to leave him and his friends alone.

Everything changed when he came into his heats.

John loved the soft-eyed willingness of alphas, loved the way they squirmed and shivered and let their mouths fall open to scent him better. He loved being able to pick the Jammie Dodgers and Frazzles from the lunches they instinctively offered him. He loved the way they let him crowd them in dark corners, let him press back into them, breathing heavily, begging just a little bit, John, please, just a taste, just a rub, just a lick, please, John, please, please.

And as the alphas matured and were removed one by one when they were no longer able to control themselves around the opposite sex, the rugby teams became all-omega, and he loved that too.

Life was wonderful.

# # #

Cocaine was perfectly marvellous. When he was high, he had no libido, no chinks in the armour, no handle for an omega to grasp and pull him this way or that. When he was high, he could rise above his instincts, could be a mind instead of a cock to be ridden, could be a person.

When he was high, he didn't care about pleasing omegas. When he was high, Mycroft couldn't compel him to do anything at all.

When he was high, he didn't wake from dreams of lying on his back, wrapped in an omega's embrace, enveloped in wet heat, squeezed and squeezed and squeezed until his orgasm was pulled out of him and he could come apart, held safe inside a strong body, held safe within a strong will. When he was high, he didn't dream of surrender and submission and wake to a puddle of semen and a cold, empty ache in his chest and fury that his genes had cursed him so.

He stayed high as often as he could.

# # #

Sex was brilliant.

John was always careful. It wasn't like it was hard to be responsible; all you had to do was roll on a bloody condom before you ejaculated so you didn't bond before you'd planned to, and take your after-heat pill. There really was no excuse, and he had no patience, no patience at all with omegas who couldn't be arsed and ended up with mates or babies long before they could support them properly.

He was going to have a damned good career: he was going to be a surgeon, which meant he could heal people for a living and God, that would be brilliant too, almost as brilliant as sex. It was the best part of sex, actually, aside from the orgasms, of course: the warm satisfaction when a desperate, shaking alpha put himself in John's care, letting John make it better—that was healing, that was what he craved every time he steadied an alpha's hands on his hips and shoved himself onto a lovely swollen cock.

Because alphas did have a rather shitty lot in life, and John couldn't do much about that, but he could make sure any alpha he shared a heat with was safe and respected and really, really well fucked by the time he was finished. It wasn't like it was a bloody sacrifice on his part. And he loved it, oh, he loved it, all of it, loved surrounding hard, hot flesh, loved the whimpers and shouts, loved the way semen would drip down his thighs when he pulled the orgasms from his bedmate.

Sometimes he fantasised about leaving off the condom, letting his ejaculate soak his partner's skin, triggering the mating bond, feeling the knot rise for him to clamp down on. He thought about how he would finally feel full. About how he would finally never again feel alone. About how grateful his alpha would be that John could make it better, so much better. Mostly, because he was in his twenties and randy almost constantly, he thought about how incredible the orgasms would be, orders of magnitude more intense, the result of alpha hyperejaculation. Someday. Someday.

There was so much he wanted to do before then.

# # #

"Your heart stopped beating, Sherlock! That is the very definition of 'dead.'"

Oh, bollocks. Brain death was the only one that mattered, and he'd been full minutes away from that. Sherlock scoffed. Tried to. The endotracheal tube had badly irritated his throat and the sounds he made were not the ones he had intended.

He'd been doing so well. He had the cocaine and the little flat on Montague Street and a man on the Met who was starting to pay attention when Sherlock told him things. Life was not terrible. Mostly. Certainly not as long as he had the cocaine.

"Piss off," he croaked. Mycroft would take away the cocaine.

His brother regarded him for long moments, and Sherlock steeled himself. He would not co-operate. He would not. He was not a child and Mycroft couldn't bend him to his will anymore.

Mycroft slowly lowered himself into the cheap plastic chair by the bed. He bowed his head until his forehead touched the mattress, beneath the level of Sherlock's. He dropped his shoulders, rounded his back.

"Please," he said. "Please stop this. I will pay for a clinic. I will buy you a flat. I will agree to any terms you choose. Just please stop before you harm yourself again."

It's the pheromones, Sherlock told himself shakily, after a long moment. Biological manipulation. He's not begging. It's just chemicals, just the deliberate triggering of alpha instincts, it's just biology, it's not real.

Eventually he rasped, "All right."

Mycroft exhaled. He did not lift his head. "Terms?"

"You never come close enough for me to smell you again."

Mycroft did not make a sound. He nodded. Stood. Collected his coat. Paused on the threshold. Cleared his throat twice. Said, "Agreed," and walked away.

It wasn't at all what Sherlock had thought power would feel like.

# # #

A punch in the shoulder spun him around, and he was falling, falling. Murray was shouting, "Watson!" and he sounded so scared that John knew it was bad, very bad. Then the pain grabbed him by the guts and tore all the air away everywhere and he tried to roll to cover but his arm—his arm wouldn't—Please, God, please, God, please—

During the months that followed of surgery, septicaemia, brutal physical therapy, sterile rooms that smelt of antiseptic and, later, a sterile bedsit that smelt of mildew and solitude and uselessness, John needed to believe that shot, the one that had ended both his careers and sent him home and meant he was never questioned about the Incident, had come from an enemy sniper.

Please, God. Please.