John immediately recognises the white stick in Sherlock's hand when he walked into the bathroom to brush his teeth. His mind goes a mile a minute about what this could possibly mean.
Did Sherlock... with a woman? And when? Was Sherlock already bored of him? Relationships weren't supposed to be Sherlock's area and their relationship was already a statistical anomaly as it was. And now there was a possibility of Sherlock having a child with someone else!
John swallowed and thought back to a few hours before. They were pressed together on the couch, panting after a round of passionate sex, and Sherlock was even whispering endearments to John in that relaxed, unselfconscious manner that John rarely saw in him.
He thought back to the whole time they'd been together. He thought back to the argument about sentiment and chemicals in the brain that Sherlock loved quoting. He wondered if Sherlock would give him that line when he delivered whatever bad news there was.
Sherlock didn't even seem to be making an effort to hide it from John. He didn't lock the door, and he didn't look guilty at all.
"Really John, you have such a vivid imagination. I can see where all that literary flourish with which you write your blog comes from."
The words were uttered with Sherlock's usual flippant wit but John noticed his pale face and the minute tremors in his hand. John's own hand started shaking in response and he was about to demand answers when Sherlock's attention was drawn to the test.
"Oh! Negative."
Sherlock rested his elbows in his knees with a sigh.
John cleared his throat, making Sherlock remember that he was still in the room.
"What? Oh, John, of course I haven't been sleeping with anyone else. You know you're the only one I..."
Sherlock turned his face away and mumbled the end of his statement. Public, or even private (in this case), declarations of love or affection were something Sherlock was very shy about but the flush on his cheeks spoke enough for John and he couldn't help the warmth that bloomed in his chest. Sherlock could be a superb actor when it suited him during cases but when it came to the two of them he was completely guileless. John didn't believe that Sherlock would cheat on him.
"I was feeling out of sorts and well, after our activities earlier I thought I might be pregnant."
With all his agitation drained out, John breathed his own sigh of relief. Good, everything's fine-Wait, what?
"Sher-Sherlock-" John didn't know what to say. Well actually he did; many things, in fact. He just didn't know where or how to start.
"Didn't your parents ever talk to you about the birds and the bees?"
Blank stare.
"Right. Well then, didn't Mycroft ever tell you-" But that was too disturbing to comprehend, even for John. He could just imagine prepetually-concerned-about-baby-brother Mycroft giving a young Sherlock the most comprehensively detailed and traumatising sex ed lesson ever. But that didn't seem to be the case since Sherlock was still staring at him.
Best get to the point then.
"Sherlock, men can't have children."
Sherlock looked hurt. "John, there are plenty of same-sex couples who have children."
John put his hand over his face. "Sorry, I meant to say, men can't get pregnant."
Sherlock went silent and John went silently crazy. Is this for real? Is he just taking the piss? Is this another experiment? Where did he even get a pregnancy test? I certainly don't keep one. And he hasn't been out all day!
But John said none of these. He knelt in front Sherlock, steadfastly ignoring the current baffling manifestation of the detective's spectacular ignorance. He cupped his cheek and rubbed his knee in what John hoped was a comforting gesture.
"You said you were feeling peaky?"
"I'm probably just coming down with something then. There is that bug going around the yard for the past week."
Sherlock felt feverish under John's hand so he decided that bed rest was in order. Sherlock allowed himself to be led back to their room and tucked into bed with uncharacteristic silence. John left for the kitchen and came back with paracetamol and a glass of water.
Deciding that he couldn't leave things in this awkward, precarious balance, John opened with:
"Sherlock, is there something you want to tell me?"
Sherlock's 'No' was muffled by the sheets.
"Do you want children?" It came out suddenly, and John thought, is that it? Does he want kids?
A minute of silence passed. Sherlock took the medicine and John didn't prompt or say anything else.
"Children require time and attention. I would have to make compromises with my work, John. You know that."
Yes, he did.
"But maybe, sometime in the future... It wouldn't be a bad idea. We could do it together."
John couldn't see Sherlock's face. Sherlock couldn't see John's face either, for which John was glad. Until this point he'd harboured anxiety about Sherlock's mercurial nature and his tendency towards boredom. He'd been ecstatic when their relationship began, and he still is. He didn't want anyone else-couldn't imagine being with anyone else, and he had hoped Sherlock felt the same.
John bit his lip and knew then that he has nothing to worry about. Children? In the future? Together. Not a bad idea at all.
He joined Sherlock on the bed and took his hand.
"There are adoption agencies, you know. We could go to one when you-well, when we're ready. They match prospective parents with children who don't have parents of their own-"
"I know what adoption agencies are, John. I'm not stupid."
John couldn't help but laugh at that. After today's bizarre events, he wouldn't put it past Sherlock to not know about adoption agencies, or-or anything else, really, John thought.
"Right then."
As they fell asleep John started plotting out just how he would correct this glaring gap in Sherlock's knowledge the next day.
Maybe he should enlist Mycroft's help.
Notes: For the Kink Meme prompt:
John walks in on Sherlock in the bathroom to see that he's taking a pregnancy test. Apparently Sherlock got a pregnancy scare from the passionate night they had earlier and the fact that he's feeling a bit sick.
Apparently Sherlock must have deleted the fact that men can't get pregnant.