Note to anyone who personally knows me: you are not allowed to read this next bit. Feel free to imagine it's full of chaste cuddles and kisses.

To everyone else: First Heat at last. Warning for the non-con inherent in this universe, but not specifically in this chapter.

It didn't hit directly. Sherlock had plenty of time to take measurements and to eat and to brood as the Heat slowly crept upon him, like the tide coming for a sandcastle. John had time to quietly send out a few texts warning people to stay away. Because entering the domain of a transitioning pair might be considered a faux pas. Entering the domain during a heat was considered at best criminal and at worst suicidal. Alphas protect.

"Are you comfortable?" John asked after that was done, sitting gingerly on the bed.

"Your cock, which has grown to almost double a beta's size, is about to be shoved into a hole that didn't exist yesterday inside my body. And apparently I'm going to be begging you for it. Why shouldn't I be comfortable?"

John looked so distressed at these words that Sherlock almost regretted them. Almost. He felt he had a right to feeling a bit petulant about the whole issue. It wasn't even the impending sex that bothered him. John might have been an intimidating size but his own body was designed to handle it. Logically, he knew that. And his explorations of John's body had been enjoyable, so he had no reason to believe penetrative sex wouldn't be.

It was the 'begging for it' part that he dreaded. His mind so taken over with lust that he was reduced to the idiocy of the masses. He wanted his first time to be a time of exploration, of discovery. Would he even remember the details, the sensations afterwards, or would it all be one big blur of desire and pleasure?

John's face matched Sherlock's for abject misery. Not that Sherlock cared. He knew it wasn't fair, but he couldn't help but feel a bit cheated that John got to be the alpha. John was now stronger than Sherlock. John wasn't the one who was about to be entered in the deepest manner imaginable. John could, once the heat had sufficiently addled his senses, hold Sherlock down and plow into him and there was nothing Sherlock would be able to do to stop him. Which didn't seem to stop John, at this moment, from looking close to crying.

"We don't have to…I mean it's harder but…there are, er, toys we can use…"

"First heat completes the bonding. We aren't supposed to use toys."

"I'm not going to rape you, Sherlock."

And Sherlock knew that. He knew that about John. But everyone said that heat drove alphas and omegas mad with lust. Alphas were known to be helpless in the face of any omega in heat, their own or someone else's. Rape charges were very rarely prosecuted because the alpha wasn't considered to be mentally sound at the time. On the other hand, assault and murder chargers also were only rarely brought up against any alphas defending their omegas.

"It won't be rape, though," Sherlock pointed out. "I'll be begging for it. You'll be out of your mind with need. We won't be able to help ourselves. And we're supposed to have sex. It finishes the bonding. It's unhealthy, otherwise."

"I don't care. I won't rape you. If you tell me, right now, you don't want to do it, then we won't. I don't care how much you beg later. I don't care how hard I get. Tell me now, while we're both clear minded, and we won't have sex. There are treatments we can do instead, to finish the bond. I'm a doctor. If I have to, I'll knock myself out. I'll take something that won't let me get hard."

"You will not! You know what happens when you use drugs to interfere with first heat!"

"I don't care. I'm not hurting you."

The two men stared at each other. Sherlock felt something well up inside, something suspiciously like a sob that he wasn't about to let out. Alphas weren't supposed to act like John.

Omegas weren't supposed to act like Sherlock. Perhaps it was time to let go of 'supposed to'. They were soulmates, compatible in every way imaginable. Did it matter if it was biology or a higher power, chance or fate? They didn't have to do anything. Sherlock didn't have to have sex with John.

"I want to."

"What?"

"I want to have sex. With you. During first heat, I mean. I want…I…can we record it?"

John was staring at him. He wasn't grinning with excitement or sighing with relief that Sherlock had given in. He was studying him. Probably trying to find the truth of Sherlock's words in his expression. Of course. He wanted to be sure. Perhaps Sherlock should offer a better explanation.

"It isn't the sex part that I didn't want. I'm not scared. I just…I don't want to lose my mind to it. I don't want to lose myself to…to lust. But if I record it, I can remember, I can…I can know."

John looked a bit bemused now.

"You know, you are probably one of the only people to ever propose recording first heat and not intend that video to be used as porn."

"I always said I was singular."

Now John was smiling, not with excitement and lust, but with fondness. And then a new thought occurred to Sherlock.

"Do you want to have sex with me? I won't rape you, either."

John's smile didn't break. If anything it grew bigger.

"Yes I want to have sex with you. And yes you can record it. Yes."

After that, Sherlock found himself feeling restless. He remade the bed with new sheets, condescended to eating some of the banquet John insisted on preparing, arranged pillows. He wondered what was taking his biology so long. Now that he had accepted it was going to happen, it wanted it to happen already.

His body felt strange. Antsy, and full of useless energy with nowhere for that energy to go. His skin felt rough and sensitive and it was just as well they were wandering around naked because he didn't think he could stand clothes.

And then he felt…strange. Warm. Was that heat? They did call it 'heat' after all. Warm and alive and somehow weak in the same moment.

"John?"

John didn't answer, just reached out gently and led Sherlock towards the bed. His nostrils flared and his eyes grew dark and…oh. Sherlock could feel himself growing wet, a very strange, very new sensation between in legs. He felt…empty.

John inhaled deeply and made a noise, something like a growl. Sherlock waited, feeling strangely curious to see what an alpha growing mad with lust might do. Would he throw him down on the bed, climb over him, claim him?

John did none of these things. There was no throwing, no show of strength and dominance. John gently pulled and Sherlock allowed himself to follow.

"You're almost ready," John whispered, "I can smell you. You smell…perfect. Come, lie with me. Please."

According to popular literature, according to the pamphlets, according to everything Sherlock knew to be true about alphas and omegas, they should be descending into a mindless, primal session of need and sex.

But Sherlock didn't feel mindless. He felt…single minded. He never felt single minded. He always had at least five separate ideas in his head at all times, more if he were working. His single mind was completely occupied with John.

This wasn't the haze he feared, the blur. This wasn't him giving and John taking. This was focus, complete focus, on a single moment, a single person. Was this what he had feared? This was brilliant.

He had enjoyed exploring John's body before, his reactions, and now there was completely new data pouring in, data untainted by distraction or division of attention. John's body felt like a tight coil beneath his hands, full of pent up energy, ready to explode. His eyes were black with lust, lit up with wonder, with…love? With something precious and fragile.

John's penis was already hard, huge and purple. A shudder went through his entire body when Sherlock reached out to touch it.

"John?" Sherlock whispered, though he wasn't completely sure what he was asking. Sherlock was lying back on the bed, John partly next to him, partly above him, propped up on one arm, one hand reaching lightly to stroke Sherlock's belly.

Somehow that light touch felt like fire against his skin. Not painful but burning. Heat. There was heat between his legs, in that new place, the place made just for John. It felt so empty, clinching at nothing, and he could feel something dripping out. It was a very odd sensation.

And John still didn't take.

"Please," John whimpered instead, "Please. May I, Please, Sherlock, please."

Sherlock had never in his life seen such a show of raw strength. The full strength of an alpha, and it wasn't being used to restrain, to conquer, but to hold himself back. Sherlock had never realized the power in resistance. John looked like he was in pain with his need, actual pain. His hips kept thrusting at the air and he was almost crying, whimpering, begging. A pearl of liquid dripped from his hot, needy shaft and landed on Sherlock's thigh. Still he didn't make any move to thrust into him.

All that power, all that strength, and John had given it all to Sherlock.

"Please, I need, I need," John was outright sobbing now, his face twisted in actual agony, and it shouldn't have felt as delicious to Sherlock as it did. It wasn't that he wanted John to be in pain, but the control, the fact that John was in agony for Sherlock, that gift was not one to be taken lightly.

And Sherlock needed right back. He wanted to feel John inside him, all the way, to burn into his very core. He wanted to record every new sensation inside his mind palace. He wanted to feel everything. He didn't release John though. Instead, he pushed him back onto the pillows, and climbed over him.

He moved instinctively until he felt the tip of John's penis brushing against his hole. Oh. That felt…new. Slowly, carefully, he breached himself on the tip of John's cock. John shuddered with something like relief, his hands grasping convulsively, one at the sheets, one at Sherlock's hip. He didn't pull him down, though, or hold him up. He just held on, still holding back, shaking with the effort to not thrust.

"You'd stop for me, wouldn't you," Sherlock whispered in wonder. "Even now. If I said no, you'd stop. It'd hurt but you'd stop."

"Yes. Please. Please, Sherlock, please, let me, I need…please."

Sherlock slid down, slowly, marveling at the sensation of being filled, listening to John's litany of 'thank you thank you please thank you'. John filled him. And filled. He never thought it would go so deep, feel so…intimate. This was a space created just for John, and now John was filling it, completely, buried into his very soul.

It felt hot, literally hot, inside of him, and he could feel it throbbing. He was feeling John's heartbeat, he realized, and there was something remarkable about feeling it from the inside, as though they were sharing his heart together.

"Can you feel my heartbeat?" he asked, curious. "What do I feel like, inside?"

"Glorious," John murmured back, his voice thick with need but also awe, wonder. And then, "Yes, I feel your heartbeat. I feel…I feel you. Around me. Slick for me. Hot. You're tight, so tight, like you were made for me."

"Yes," Sherlock answered. He held himself there for a long moment. He could still feel John quivering with pent up need, desire, and he wanted John to move, wanted to let him take, wanted to give his gift back again and just take everything. He still didn't move, didn't ask John to move, reveling for the moment in the denial, in the very sweetness of the pending precipice to come. And then…

"Take me, John, now."

And with a sob, part relief part joy, John did.

He moved beneath him, holding Sherlock so carefully, his movements so gentle it was almost painful because Sherlock needed, just as much as John he needed. He wasn't entirely sure what he needed just that being filled wasn't enough.

"Please, John, I don't know…I think I need it harder. Please?"

He had always feared the begging. But this…this wasn't him giving in, it was him allowing, him giving, yes, but not giving in to lust. This wasn't his mind overcome by his body; this was his mind allowing his body to be fulfilled.

John turned them over, laying Sherlock against the pillows, and they looked at each other, not lost in each other but found, and he gave Sherlock exactly what he needed in strong, hard thrusts. His new passage was sensitive and it hurt, but not the kind of pain that made Sherlock pull away because it also felt perfect. Pleasure welled up inside him and it felt right.

Then John reached down and grasped Sherlock's cock and it felt more than right. He hadn't even noticed he was hard, so concentrated as he was on the new sensations.

This was pleasure, being brought to completion from within and without.

He still didn't lose his mind to sensations. It wasn't a blur. He was able to categorize and concentrate and to reach out and touch and explore each new sensation, each new reaction from John, each new event.

Coming to the feel of John's hand, to John thrusting deep inside his body, was a completely new experience. The seed from his cock was minimal but the reaction inside his core was glorious and for one long moment every thought, every sensation, was narrowed down to the sharp point of a single act.

John groaned deeply, and Sherlock did that to him. He made John feel this pleasure, this need, this completion. And he felt when John came, deep inside him, placing a bit of John inside Sherlock's body where no one would ever be able to remove him again.

The sensation of the knot swelling at his entrance was not the painful joining Sherlock had feared. It felt odd, but right, and Sherlock felt another wave of pleasure sweep over him, making him gasp in surprise.

"Sherlock?" John asked, his face close enough to kiss, his arms holding tightly as they were knotted together. Sherlock wasn't sure if he could answer. His mind felt as full as his body, processing the new sensations. An entire new wing would be needed for his mind palace.

"Sherlock?" John was starting to sound concerned now. Perhaps Sherlock should make an effort.

"You are brilliant," he managed to get out, and John's arms tightened around him.

"I'm so glad I found you," John murmured into his ear. "I'm so glad you're mine."

And then they held each other in silence, and just were.

How could Sherlock have ever dreaded first heat? After all, he always knew he'd be sharing it with John.

Author's Note: And there's the sex scene finally done. Hope it satisfied. I admit my experience in writing sex scenes is a bit lacking. Also, note that I've now caught up to myself. Which means that while there will probably be at least one more chapter to this story, I still need to write that chapter so it might take more than a day for the next bit.