(A/N: This is basically smut without plot so you can just go ahead and not read it if that bothers you.)

Omegas need a brief recovering time after giving birth, but after only a few months the omega will go into heat once more.

… …

Like clockwork, Sherlock's heat crept back on him.

The signs were there a few days before it set in. Sherlock became increasingly irritable, prone to shutting himself away for hours at a time. His skin became hyper sensitive and everything but his oldest pajamas and his silk robe seemed to irritate it.

He refused to dress, refused to take any cases, refused to talk to anyone but John and the children (and sometimes Mrs. Hudson, but only if she came bearing tea and biscuits).

It…annoyed Sherlock that he felt this loss of control over himself. He prided himself in being a low instinct omega, the same way that John prided himself in being a very self-controlled alpha. But biology oftentimes got the best of him, and Sherlock found himself, completely against his will, succumbing to the flood of hormones in his brain.

While Sherlock stewed in a black cloud of irritability, John quickly and discreetly made arrangements with their legion of baby sitters. They used to leave Silas with Mrs. Hudson, but they couldn't impose two four month olds and one sixteen month old on her for several days.

The children were to be passed off like batons in a relay. Mrs. Hudson would watch Silas for the first day while Molly watched the twins. Then Lestrade would pick up Silas from Mrs. Hudson on the second day, and he and Molly would take the babies out for the day.

Then Donovan, of all people, volunteered to look after them for a few hours until Mycroft picked them up the second evening. Mrs. Hudson would be brought to Mycroft's nice flat, where she would be assisted by Mummy until the heat ended.

It kept anyone from being too overworked and everyone from feeling offended that they weren't asked to baby sit.

Sherlock was annoyed with the entire process (and the idea of anyone watching their children for as long as the heat would take) and left every single bit of arranging to John, declaring that every baby sitter was equally horrible and so he didn't care who watched the kids.

That was a blatant lie, as evidenced by the fit Sherlock threw when he discovered that Mycroft and Mummy had gotten themselves involved.

Sherlock sulked for so long that John had to ask Molly to come over and help with the twins because he couldn't handle it alone for more than a few hours.

Sherlock had received a lecture for that one, and barely resisted the impulse to shoot the fucking walls.

Of course Sherlock knew he was being cold and irresponsible and irrational. He just couldn't do a damn thing about it. That's what was annoying about this entire situation.

Duh.

Nevertheless, by the time the heat finally set it, the children had all been taken care of. Sherlock had fallen into a haze of apathy and was sprawled on the sofa when he began to feel overly warm in his pajamas. (Which was ridiculous because it was cold outside and in the flat.)

He slowly stripped, every touch of cold air against his skin feeling like a reprieve.

He knew that John was wandering around the flat somewhere, reluctant to bother Sherlock while the omega was still being pissy, and finding himself bored without the constant activity that comes along with babies.

But Sherlock didn't feel like calling him quite yet. He was only just beginning to feel a dampness of his thighs. It would be a while before he was prepared, and there was no sense in getting John all worked up just to tell him he would have to wait.

Sherlock knew that the only reason John had put up with him the last few days was that he was looking forward to this more than he let on. They usually avoided the hassle of penetration when Sherlock wasn't in heat since their respective biology didn't match up. Sherlock, quite simply, couldn't take John without a good deal of preparation and a fair amount of pain. He'd endured it for a while, but John caught on, lectured him sporadically for several days about speaking up when something was making him uncomfortable, and refused to have him in that way outside of his heats.

They made do, of course. Sherlock believed, at least, that John was in a state of sexual contentment. Both of them rather fondly remembered their first time together, and that hadn't involved any penetration at all.

Sherlock smiled slightly as he finally stripped off the last of his clothes.

Good times.

The next few days would be different. They would get to be together the way that they were supposed to, alpha and omega, twined so tightly together that they lived and breathed as a single unit. Some excitement thrummed in Sherlock's stomach, and that wasn't the only part of his body that was taking interest in the thought of the next few days.

Sherlock stroked himself lazily, remembering what he could of the other heats he'd spent with John.

Only three others, he mused. Of the nearly two and a half years he had known John, he had spent a year and a half of it pregnant.

Which was really quite horrifying to tell you the truth. Sherlock had taken precautions to ensure this heat wouldn't result in another child. He was on a more effective (so said his extensive research) birth control than he had been when the twins were conceived, and John had been instructed in no uncertain terms that he would be using a condom.

No more children, they had agreed, both exhausted and covered in vomit at three in the morning. They had enough children.

No children, no trying to get pregnant, just three to five solid days of sex.

It was going to be glorious.

"You're making a bit of a spectacle of yourself," John murmured, his voice low, from the kitchen doorway. So that's where he'd been.

Sherlock cracked and eye open (when had they drifted shut?) and took stock of his current position.

His legs were spread wantonly, one on the floor, the other edging up the back of the couch. One hand was busy fisting, while the other was drifting steadily lower, between his legs and back.

"It appears to be starting," Sherlock deadpanned, slowly his strokes. He arched his back slightly, putting on a show.

He tried glancing subtly back at John, and was rewarded with the sight of the alpha clenching his fists in restraint, watching Sherlock with a positively predatory expression.

… …

God, Sherlock was a fucking nightmare before his heat.

John had forgotten about in, in the year since his last one.

It was a pleasant thing to forget about.

Because, John repeats, Sherlock is a nightmare.

Sherlock never took his constant state of irritation out on the children, though. He had that much to his credit. He would leave John alone with them for nearly a day, though. He only snapped out of that funk when John resorted to calling in some help.

He only had to arms after all. You could not soothe three children with two arms.

But John was still an alpha. And a man,

So watching Sherlock like this, desperate for release, for gratification, spread out on the couch and looking so fucking delectable that John could just—

John took a deep, shuddering breath. Sherlock wasn't ready for him yet. He had to stay calm.

But, oh, then his hand move quicker and his back arched up and before long Sherlock forgot about teasing John and putting on a show and just chased his own pleasure and then—

Then John had to leave the room because, for fuck's sake, he could only endure so much.

"John?" Sherlock called out, a worried note to his voice.

"In the kitchen," John take, taking deep, soothing breathes and trying to think about random things. Like mail. Or doing the laundry. Or politics.

There was a pause.

"I probably shouldn't have done that," Sherlock admitted after a moment.

"You're fine," John called back. "I'm just…calming down."

Now the pause was awkward. "I'll…" Sherlock started. "I'll wait in the bedroom. I should be ready a few hours."

"Right," John said, nodding although Sherlock couldn't see him. A few hours. He could do this. "I'll just be banging my head against the wall until then."

Goddammit.

… …

Waiting for the heat to sink in was a slow sort of agony.

Sherlock was a writhing creature of want and he had to wait until that want could be satisfied. Poor John wasn't much better. Once, he had to lock himself in the loo until Sherlock deemed himself ready.

Minutes blurred into torturous hours until finally-finally—John tentatively opened up the bedroom door.

"Sherlock?" John called out softly. "Are you ready?"

Sherlock was past the point of being able to answer. John took that to mean that, yes, he was ready.

"Alright." John said softly. "Alright, don't worry. I'm here now."

His voice was shaking with ill-concealed excitement and anticipation, and under normal circumstances Sherlock would tease him about it. Now, however, it only sent another stab of desire into him. He whined pathetically, ready to beg.

"I'm here," John kept saying as he quickly shed his clothes. "I'm here now, you don't need to worry about a single thing. I'll take care of you. I'll make you feel so good. Pretty omega. My mate."

John quickly scrambled for the condom before he lost himself to the rut. Sherlock just watched him in a haze, already rolling onto his stomach to present himself.

"God, so fucking gorgeous," John whispered fervently, sliding onto the bed and moving to kneel behind Sherlock. "Fucking mine."

"Please," Sherlock whined. "John, please."

John teased Sherlock, slipping a finger in and humming in delight when he found the omega prepared. "So slick for me," John sighed, the picture of content. "So good for me."

Sherlock felt strong, warm hands grip onto his hips and then finally (finally!) John pressed into him.

It still stretched and burned, but his body was ready to accept the intrusion. And the feelings of desire and satisfaction overrode any of the pain anyway.

Both of them were too far gone to drag it out. John's thrusts quickly became fast and hard and the delicious almost-but-not-quite-too-painful feeling of it set Sherlock further on edge. John wrapped his arms around Sherlock, pulled him up for better leverage, then—

"There!" Sherlock croaked as soon as John hit his prostate.

"I know," John chuckled, coming back to himself slightly. "I remember."

John sped up, his accuracy unfailing, and after an embarrassingly short amount of time, Sherlock was almost sobbing, begging incoherently for the knot.

Because he needed—he needed just a little more. He couldn't finish without it.

"Yeah-almost-just," John gave a few short, shallow thrusts before finally pressing up and pulling Sherlock down.

Sherlock would never ever tell John (for fear he would stop) but the knot hurt like hell. Each time it popped past the ring of muscle, Sherlock had the irrational fear (even in the haze of the heat) that something would rip or tear.

But, for once, biology was on his side. John always fit. The knot never damaged him, just left him feeling a bit sore.

And, oh God, it was exactly was he needed. The sensation of being completely filled, of feeling utterly owned, was enough to tip him over the edge. Sherlock came, shuddering, In John's arms.

John wasn't far behind. He pulsed inside of Sherlock, although the condom prevented the hot spill of seed.

A bit disappointing, said the stupid little omega in the back of Sherlock's mind.

Shut up, Sherlock told it sternly. No more babies.

John carefully repositioned them so they were lying on their sides. Sherlock wriggled slightly, but they were locked together. Close, so very close. Twined tightly in a tangle of limbs, gasping against each other's skin.

"I love you like this," John murmured, nuzzling Sherlock's neck. "All warm and flushed and pliant."

Sherlock hummed. "You're not bad, either." John's hands were running up and down Sherlock's ribs. Sherlock quickly grasped them in his hands, lacing their fingers together. "We don't have long," Sherlock said, "before the heat comes back."

"I know," John sighed. "Let's just…enjoy this part while we can. We won't be coherent again for a few days."

Sherlock snuggled closer.

"How do you think the babies are doing?" Sherlock asked, breaking the silence.

"They're fine, I'm sure."

"I suppose Silas did survive being held by Anderson."

Sherlock felt John smile against the back of his neck. "They're strong, our kids."

"Well, they better be," Sherlock huffed. "They'll never be able to keep up with us, otherwise."

"God, we're going to buy them little coats and scarves, aren't we? They're going to be running around with pocket magnifiers and solve crimes before they're out of their nappies."

"You say it like it's a bad thing," Sherlock complained. "But really, that sounds like the best thing that could possibly happen."

"Perhaps you're right, darling."

"You know I am."

END

To be continued in Part Three