Sex came in cycles, of course, but cases did not. Around the first of the month, John cursed whenever the Sherlock's mobile rang with the tone he'd set up for Lestrade (a three note riff, Beethoven's fifth --it always made John's teeth grit that the final DAH never came). John had much better things to do, in bed, preferably with Sherlock.
By the tenth of the month, John couldn't care less about sex and was if anything more eager than Sherlock to get a call and head out on a new adventure. He felt like he was ten again, racing around the alleys, poking in skips, staying out all night watching through windows hoping to catch a clue or solve a mystery.
In other words, he behaved normally.
Sherlock was much more erratic in his cycles. He was prone to utterly perverse bouts of affection during what should have been his sexual ebb – demanding kisses and even once asking for a handjob on the fifteenth (John, horrified, had said no). On the other hand, he far too easily distracted by intellectual pursuits at the peak, once leaving John to take care of himself alone while he did some experiment down in the sitting room. John had refused to talk to him for days after that.
It was almost certainly the fault of spending thirteen years on the A-pill. Before John had moved in, Sherlock had taken hormone inhibitors to dull his libido down to nothing month in and month out. Before John got involved with Sarah, Sherlock had claimed to think sex was a waste of time and energy best spent on intellectual pursuits.
John, who had been ordered to take the same drugs while in Afghanistan, couldn't understand why Sherlock would take them. No one liked taking the A-pill, it was just one of the necessary sacrifices of war, like constipating food and sleeping rough. There were many times when he and his mates had cursed the fact that even that most basic form of entertainment and stress relief was denied them. But then, no one ever got inconveniently pregnant on the battlefield this way.
Sherlock was a very strange sort of a person.
John wondered if there might be something permanently wrong with Sherlock's hormones, but it seemed to be one area that the man was resolute in not exploring. "If you wanted someone more properly rhythmic you should have stayed with Sarah. I prefer not to be so completely predictable."
That had led to an argument that ended with John spending the weekend with Sarah. Not that anything came of it, their cycles were still hopelessly misaligned, but it was enough to make Sherlock properly contrite when he returned.
As well he should be, since that was largely his fault, too. Over months of dating, Sarah and John's cycles should have drifted closer together until they went into sync. And they certainly would have if not for the fact that the day John had started dating Sarah was the day Sherlock suddenly decided, after thirteen years, to go off the A-pill.
Of course, once they started, Sherlock's cycles aligned to his instantly, and that was that for Sarah.
But years of A-pills had done their damage. John suspected that Sherlock was so hormonally confused he might not be able to have children at all. So, apparently, had everyone else. Including Sherlock.
Which is why it came as a complete shock when Sherlock said one afternoon, "I'm pretty sure I'm pregnant. Congratulations. I suppose." He had on his sulkiest face.
John spat out his tea. "What?"
Sherlock shrugged. "It's dreadfully inconvenient. But if Sally Donovan can manage motherhood and work, I'm sure I can, too."
"How on earth could it happen?"
Sherlock gave him a dry look. "Well, I believe you put your penis into my vagina during the height of our fertile periods and nature took its course."
"You mean you weren't taking birth control?" John smacked his face. It stung. "How can you faithfully take the A-pill every day for thirteen years and forget to take an ovulation inhibitor for a single week?"
"I've always preferred the male role. I wasn't anticipating it would come up."
John flushed. "So it's my fault then. For asking to top once. You could have told me you weren't on anything. I would have put it off until next month."
"I'm not blaming you. I was caught up in the moment. I'd never been topped before, you complained that me being male all the time was selfish. It was surprisingly nice, though I think after this it would be better if I went back to being an exclusive male."
"After this. Little late don't you think?" Sherlock said nothing and John relented. "All right. What are your symptoms?"
"Breast tenderness, some cramping a week ago. Heightened libido. Heightened attraction to you."
"The last two could just be typical of your peak coming on. Cramping could be anything. Did you skip your period?"
Sherlock smiled somewhat bitterly. "I haven't had a period in thirteen years. I honestly thought I was sterile."
"Well then, have you taken a pregnancy test."
John breathed a sigh of relief. This could be a false alarm. "Okay," said John. "Let me see your chest. We might be worrying for nothing."
Sherlock unbuttoned his shirt and spread the cloth apart. His chest was still flat, but the nipples had become significantly puffier. John reached over the corner of the kitchen table and ran his thumbs over them. Sherlock hissed. "You've got breast bud development."
John asked the next question and steeled himself for the answer. "Are you going to keep the child? It's early enough – your body hasn't made any obvious changes yet…"
"If I didn't want it, I wouldn't have told you about it." His – her eyes (John would have to get used to the switch in pronouns) were locked on her tea. "But, if you don't want it, I suppose I can stop it." She looked up. "Do you want me to?"
"No." John was resolute. Part of him had always longed for a child, but he'd been resigned that it wasn't going to happen. Especially not with Sherlock.
He stood up and walked around to Sherlock's side of the table. He laid a comforting hand on her shoulder. Sherlock stiffened for a second before relaxing against John's hand.
"I'm here for you," said John. "We'll figure this out."
"We can still do cases – I'm not going to let this slow me down. I'm not going to turn boring on you. Sally's a single mother and she manages fine. I have your help. It should be easier."
John smiled wryly. "It's not going to be the same, Sherlock. You know it can't be. We'll adjust."
Sherlock became unbelievably tense. "This wasn't like going off the A-pill, John. I didn't do it to trap you."
So she finally owns up to that at last to that sly piece of manipulation, John thought a little bitterly. But her next words took him completely by surprise.
"If you decide to leave me, I'll understand," Sherlock said. "I won't pursue you."
John didn't believe he'd heard her right for a moment. Then he just plain out didn't believe the words she said. Part of him was insulted that she thought he'd shy away from his duty. But he knew Sherlock well enough by this point to parse her thinking and he accepted the lie for what it was: a guilty apology.
"I'm not a sperm donor," John breathed against her neck. "You never had to be unhanded to keep me, Sherlock. I've been yours since the day we met." He snuggled her tight. "Though let's plan the next child together."
"Deal." Because you'll be the one bearing it, she didn't say, but John knew anyway. That was fine as well.