John's consent and contact card was all but empty when he came back from the war. In the hospital, they'd had to pull him off his suppressants to avoid a conflict with his pain meds, and they'd tripped a latent heat. Even for a bullet-riddled vet, no one was about to summon Bill Murray from the front lines to help him deal with his unruly genitals.

He'd called his sister – there had been no one else.

Now, Sherlock could identify him by a single finger. Any of them. The knowledge should unsettle John, but instead it sits like a firefly in his rib cage – a warmth that feels like a secret. John finds himself looking down the list: Bill Murray, Nora and Mike Stamford, Harriet Watson, and thinking who else could do that?

Someone tries to blow them up.

When James Moriarty leaves, Sherlock moves to him like running water. "People will talk," John says. Adrenaline keeps him upright, but it will be spent soon and there will be nothing but his own elastic muscles.

"People do little else," he says, and wrenches John's jacket off – throws it like it's offended him, the explosives next. John's always been able to rely on his own adrenaline and steady hands. He doesn't have time for anything that wobbles, or whimpers, but on the cab ride home, he thinks Sherlock may have done both.

He ignores it because as long as John is there, Sherlock is allowed to wobble. That, John is starting to realize, is the point of John. It feels right, like something settled. He'd drifted after he had come home from a war; for so long, there hadn't been any point to John. John had been a series of verbs of varying levels of difficulties, wake up, John, clean your teeth, John, go for a walk. He'd had to prompt himself into each one, over and over, grudgingly.

Somehow, John and Sherlock are laughing. That is a thing John does, now. They get off at Baker Street and John goes to get the shock blanket. He considers it something like a souvenir.

"I know that isn't for me," Sherlock frowns, but allows John to tuck it around him anyways, looking like a put-out feline. John knew something about cats though. He makes a judgment call and brushed the backs of his fingers over Sherlock's forehead, meaning only to offer comfort, but stumbling onto an uncomfortable realization when Sherlock feels so much warmer than he'd expected.

John swallows around a suspicion. "Sherlock, when you said you spent a lot of time, and chemicals…"

"Oh, don't talk to me about legalities, John, it's tedious."

"A strange conclusion to leap to," John says, squinting at him. "So, shall I put you down as self-prescribed, self-made or both?"

"Honestly John," Sherlock ground out, "don't be ridiculous. You know who my father is. "

John doesn't actually, but that's Sherlock. John is almost pleased that Sherlock assumed he would know. He doesn't even have to ask: the question hovers heavy in the air.

"Mycroft and I's father is the Holmes half of H&H Pharmaceuticals."

John lets out a low whistle. "Your father is the world's leading expert in heat-suppressors."

Sherlock rolls his eyes. "Yes, John."

John's let Sherlock rabbit trail him from his original point. He redirects: "I think the stress may have derailed your chemically cultivated biology."

Sherlock sharpens in an instant. There is no better word for it: his shoulders rise to points and his eyes narrow, plush curve of a mouth pressing itself flat. John can feel the heat transfer from a foot away.

"Who can I call for you? Sherlock?"

"You've got to be…" Sherlock muttered, launching himself to his feet and stumbling for the hallway. John stayed rooted, listening to the sounds of the tap in the loo running, and what he assumed was Sherlock splashing his own face.

John's feet carry him to Sherlock, unbidden, when he hears him retch.

Sherlock is clutching a vial in one hand in a bloodless grip, and the other is braced above the sink.

"I, uh, don't really think there's anything to be done, at this point."

"Oh, is that your professional opinion, doctor?" Sherlock sneers, wiping his mouth, and John swallows down a flash of anger.

"Yes, actually. You probably should have been letting yourself go into at least one per year. This might not be happening."

"Having heats is rather counter-productive to the point of suppressors," Sherlock says, and he has to pause twice to get the sentence out. "A large enough dose of… human chorionic gonadotropin could…"

"Or it could send you into a tailspin. It's going to be unpredictable as it is." John curls his hand around the vial and Sherlock flinches. He looks terrified, defeated, and desperate. John knows what it's like to be hijacked by biology. "Let's go turn on your dehumidifier. There's still time to minimize."

Sherlock follows him joylessly, like a herded animal following the curved path. "I've been on suppressors entirely since adulthood," he tells John without looking at him. John adjusts the levels on his dehumidifier and it whirs to life, loudly, starting on the highest setting.

"Do you want to call your brother?"

"Out of the question."

"I know you don't get along, but this is –"

"Do not say that this is different, John. You have no idea."

"Well," John challenges, "who is on your C&C? You've got a few hours to make that call."

Sherlock mutters something into his hands. "Come again?"

"No one, John," he enunciates, with razor-sharp vowels.

"Okay," he says, calmly. "What would you like me to do? Shall I fetch you an aide, or call someone?"

"Don't be ridiculous, John. Who would come?" Sherlock starts unwinding his scarf, and John notices the sweat collecting in the lines of his unhappy forehead.

"Don't be stupid, Sherlock. Lestrade would. Mike, for another."

Sherlock turns a familiar look on John, and he holds out his palms, smiling faintly. "Don't deduce what you don't want to know."

He looks faintly disgusted. "That is quite enough, John."

When John met Sebastian Wilkes, he'd leaned in like he had a secret, on their first meeting. "We all hated him, at school."

Well, John thought. He moved his focus to the corner of his eye to see if Sherlock has responded in any way, and he hadn't. His posture was school-boy straight. Sebastian went on: "He went into heat in a lab, once.

"This doesn't seem the time or place to bring up childhood trauma," John said, frowning.

"It wouldn't be funny, of course," Sebastian said, looking at John, "but we'd all been so sure he was an alpha, the whole thing was quite the head-trip."

"Sounds like a riot," he'd snarled, grabbing Sherlock's hand. He could feel his pulse in his neck skyrocketing, and felt overheated, strangled by his jumper.

"What an…" John grumbled.

"Alpha." Sherlock finishes.

"Alphas," John agrees, grinning at his friend. They solved the case, because Sherlock is brilliant, and John added a few items to the list of things he will do in fear of Sherlock's life. John finds himself thinking of it now. Alphas, he'd snorted.

Sherlock's biology right now is ticking, volatile. "I'm telling you, you can weather this one alone, but after so long on suppressants, I think you should call someone you trust."

"There is no one, John. There is only you."

Everything was so complicated, now. John hated the politics of heats: the way he felt on the second day, when everything was suspended underwater and there was nothing but thick, miry want and no thought governing his behavior, just his layered hunger and wet genitals.

If Sherlock was going to dissolve into that – and considering the amount of suppressants he'd been on to forestall his heats indefinitely for so long – the next few days would be hellish. Sherlock would hate it, might hate himself upon coming up for air as his heat receded, but if John got involved, it would be more likely that he would hate him.

It would be so much easier if he'd let him call someone: Lestrade, or a professional, hell, John had spent Mike Stamford's last heat by his side as it began, just keeping him company as his wife was unavoidably detained by foul weather at the onset, and then his wife, beautiful and made of wide alpha planes, had asked him to stay. The whole thing had been lovely, and ended in a curry eaten in a nest of blankets. If John had called Mike or Nora he could rest assured that Sherlock would make it through his heat both safely (and likely pleasurably) but more importantly, with his friendship with John intact.

He had no such luck. Sherlock's face was carved out of aluminium, like all it would take to crumple him would be to grip too tightly.

Sherlock clawed at his own neck, and John thought of the way that people touched others how they hoped to be touched, and how he'd come out of his comfort zone to find John when he was riding out his heat, simply to scratch his back.

"Come on," John said, offering his friend his hand. "Let's get you to your room."

Sherlock was a bundle of nerves. "Biology is tedious," he said, frozen in his doorway.

"It can be," John allows, neutrally, turning the dial on his humidifier up to HIGH. "But I'd be lying if I said I'd never looked forward to a heat."

Sherlock feigned disinterest as he pulled his sleeve close to his face to brush at some imagined imperfection. "I—" he said, face obscured by his wrist, "might say any number of improbable and inappropriate things in the next forty eight hours."

John held both hands palm-up. "I won't hold anything you say at face value. We'll have a embargo on all emotions talk until after this is over."

Sherlock let out a long breath, like a punctured thing, and John could hear his fingernails drag over the skin of his wrist. "I'm going to go build you a sandwich. You should climb into a dressing gown, and adjust your card."

John came back without a sandwich. They hadn't been grocery shopping since the explosions, but he did find an apple and a jar of peanut butter. He went to carving with his pocket knife, and set them both on Sherlock's night stand, on top of a coffee-splattered stack of papers, beside the snow globe of a French attraction, and the small mountain of staples that held approximately nothing together.

Sherlock was in a dressing gown that John hadn't seen previously. He had something like a collection. "I mean to say," he said, as if he'd just arrived at the end of the speech and was summarizing. Perhaps he had been; it certainly would not be the first time he hadn't stopped speaking just because John wasn't in hearing range. "Perhaps I will ... make lewd suggestions. I will, ah, ask."

Sherlock looked pink around the tips of his ears. John didn't want to laugh at him, but the whole thing was so unbearable endearing. If he hadn't looked so frazzled, John would have reminded him that the whole thing was just transport.

Beg, he wanted to correct: you're going to beg. You're going to cry. Instead, he leveled a look at him. "And? What do you want me to do?"

"It's not like you're physically equipped," Sherlock said, adding a cruel twist to the words. John heard his teeth snap at the end of the sentence, like the sharp crack of punctuation on an old typewriter.

John wasn't phased, as he looked down at his arm, tucking his thumb into a fist exactly the way you wouldn't for a fight. His hands were small, but capable. "Huh," he mused. "That sort of looks like exactly what you're going to want."

"It's hardly the same thing, John," Sherlock says, as if John is being tedious. As if Sherlock isn't nude under his robe. Like Sherlock has the upper hand – all of the upper hands – and doesn't even need to grace John with his presence. John's blood would be boiling under the heat of the condescension coming off of his friend in waves if he couldn't see his trembling hands. He's trying to feel somewhat in control, he's not trying to make John feel small.

"Do you know that moment when you say, oh no, that couldn't possibly fit, please remove that from my genitals immediately? And the alpha dick who happens to be in your bed says the worst possible combination of words." Any combination will do. Just take it, yes, so close, you're doing great, you'll love it when it's settled, you look so lovely on my cock, needy little slut, you've been begging for this, oh, you were made for my knot.

Sherlock's face is a storm cloud. He doesn't have to say yes.

"Oh, what a co-incidence," John says in a flat voice, "me too. And the thing about not being with an omega is, when you feel that feeling, we tend to say, alright then, squeeze my free hand while I pull it out. Either way. I'll give you what you need or I'll ignore you and keep you fed for three days while you sob. The question is, do you want me to be hands on, or do you just want me to bring you fluids and stand guard at the door?"

"It's all going to get… rather undignified, isn't it?"

John nodded at him. He had to look up at him, but he tried not to peer up through his eyelashes, like a proper omega. This was not a normal situation, and it would not be fair of John to use a sudden onset heat to his own advantage. Any pair of mates would batten down the hatches for this kind of situation. Just because John had been battling a weird attraction to Sherlock's asymmetrical slanted face and voice like a sultry bassline in 1940s jazz, did not mean anything. For all they'd talked about it, Sherlock might prefer betas, or brunettes or, hell, women. But mostly, as John understood it, there wasn't generally a preference.

All John knew was that his best friend had a complicated relationship with his own biology and a shared contempt for alphas in general, and more specifically, the alpha habit of delegating all reasoning and critical thinking skills to their knots.

"Yes," he agreed. "but it might not be terrible."

Sherlock inclined his head, and his face softened into an expression that still seemed miserable, but at least the affected contempt was gone. When he spoke, he sounded soft. Almost hesitant. The sound curled into him like a hot drink. "In that case, John… If you would be so kind…"

This time, when Sherlock's hand went to his shoulder, John caught it. "Lay down Holmes. I know your skin is crawling."

"Unbearably," he groaned.

It was strange to be returning the favor. John had thought about it a few times since Sherlock had put his fingernails against his own skin, putting out some of his fires while stoking others.

John tries to put all of his mixed up, tangled thoughts away as he moves his hands to Sherlock's back. He's still covered by his gown across his shoulders, and John starts innocuously enough: with one palm across his left shoulder blade and the other dragging a blunt, straight path up and down the other shoulder. Sherlock twitches under his fingers, and John chases the twitch until he's given most of his back the once over.

"You keep missing it," Sherlock groans into the crook of his elbow, where his face is hidden. The back of his neck is a dull red, and John gives is a gentle rub with his short nails and Sherlock shudders violently beneath him, in a strange rolling spasm.

"Did I just his the spot or the self-destruct button?" John asks, fingers hovering a millimeter from the soft, stray hairs at the base of Sherlock's skull, under his hairline, dying to try again.

"Nng," Sherlock replies, and John brushes his thumb against Sherlock's hairline, and down the first few inches of his spine. Sherlock squirms under his touch, and John has to bite into his lip to keep in the laugh that wants to come out as an amused exhalation. John brings his hands away, back to scratching, following cues and Sherlock's own muscular tension.

"Pull this down," he suggests, tugging at the fabric – it's weird, slippery to the touch, but rough in others – and Sherlock complies not by shimmying it down his hips to drape over his bum like John had expected, but by flinging it off the side of his bed, to join the rest of his mess.

The skin across Sherlock's back is so pale, like nothing warm has ever touched it but his great coat – not a lover's touch, or the sun. Sherlock keeps arching, rising to meet him. He has four moles, and John avoids them all out of idle curiosity to see if Sherlock has mapped out the bits of himself that he wouldn't see under many ordinary circumstances, and what he will deduce from his actions.

"How long has it been since you've had a proper heat?" John asks, trailing his fingers down the back of Sherlock's arms in a way that makes his hand curl reflexively five or six times. He stays in the same place but adds pressure to stop tickling his friend.

"I was," Sherlock says, still muffled. "Ah, in my twenties. I tried to disappear from familial obligations, and it took considerably longer than I'd anticipated to get my own version functional."

John let out a low whistle. "Years?"

"I'm not worried about infertility."

"Oh, I'm shocked," John grins, and Sherlock looks at him over his arm, muscles soft, and Sherlock smiles back at him.

That's not the only complication with long-term heat suppressants, but John isn't sure where Sherlock's hormones are, so it doesn't seem like the time to pry. Things are going to get so literally and metaphorically messy in the upcoming week that he is doing his best to keep from betraying Sherlock's trust. Using his chemical imbalance to pry into his medical and sexual history just doesn't seem on .

"All of the itches have migrated."

"Oh?" John says, pulling his hands back. Sherlock flips over onto his back before John has time to brace himself – for a creature who spends so much of his time sedentary, when Sherlock is ready to move; it's like a magic trick, now you see me.

John draws his fingertips across Sherlock's chest, his long lean torso a mess of cartography: knobby ribs and the occasional scar. He has a few scattered moles on the front, as well, and he scratches around them as well for a lark.

He tries to keep his eyes on Sherlock's face, keep himself from looking downward. Sherlock's eyes are closed, but knowing him, he'd feel the intensity of John's gaze. He half expects him to shush him now, because he's thinking too loudly.

Johns fingertips reach up to Sherlock's neck, where he was clawing earlier. He brushes across the red marks with the callused flat of his thumb, and Sherlock's neck jumps beneath his hands.

"I'd forgotten how overwhelming these things are."

"Would you like me to leave you alone for a few hours, before things get…?"

"Please don't," Sherlock says.

John rests the pad of his index finger over Sherlock's Adams apple and it trembles beneath him.

There's something John's wanted to do for some time, now, and it seems like the moment has finally come. Sherlock, stretched supine across the bed, his stomach bared beneath him in a way that made it seem completely vulnerable, and John trying and failing not to look at his cock, little and pink and demure at the fork of his legs, and John thinks to himself, if this is never going to happen again, he might as well go for it. John settles himself behind Sherlock, still fully clothed himself, and buries both hands in his hair.

"Oh!" Sherlock gasps, squeezing his eyes tightly shut. His pheromones, which have been hazy and faint, but obviously present, are starting to align. John loves the heady mix of omega scents, and that Sherlock-scent in particular, which he's always kept masked under his clinical neutral wash. John puts all of his focus into carding through Sherlock's silky hair, dragging careful touches across his scalp like he's making a new discovery. For long minutes, Sherlock rocks his head back and forth in his hands, hands shifting restlessly for purchase in the sheets around him.

"Too much?" John asks, stilling.

"No, John. I need… I…"

John knows, actually. He can feel Sherlock's pheromones now with some sense he can't pin, like phantom hands pulling at his collar.

"In the past," Sherlock says, "I have not particularly been stimulated by penetration."

"Meaning, during heat you haven't felt compelled to be penetrated?"

Sherlock flushed. "I have. But, I don't typically…" Sherlock made a vague hand gesture that John assumed meant, ejaculate. It was funny: this man who could look unflinchingly into the heart of darkness, dissect patterns of criminal behavior with a look, and categorically knew of all the ways one could become deceased on an innocuous vacation to the tropics, but have him talking about his own preferences and genitals, and suddenly he was a school boy. "I just don't want you to think you're doing anything wrong."

"Huh." John moves, again, around Sherlock. He is beginning to feel like he's in Sherlock's orbit, as he nestles himself between Sherlock's legs, bringing his face up close to Sherlock's penis. "I'm an omega, Sherlock. I have no desire to treat your dick like it's ornamental."

John nosed Sherlock at the join, scented him at the heat of his groin. He pressed a kiss to Sherlock's pelvis, feeling his pulse at the tip of his tongue. And then directed his attention to the organ in question. "Hello, lovely," he smiled, before ghosting his lips across its peachy head.