John picked the crumpled Radio Times up from next to his chair and flicked through the listings, looking for Saturday's page. It was on at ten past six this week. Constantly flying round the schedules, this one! Never regular. But that was appropriate, he supposed. This was the one show John always kept up with. It was something he'd grown up on and the opening titles comforted him, even if they weren't quite the same as they'd been when he was a boy. It was also the closest thing on the telly that he could relate to. Yes, yes, they were flying through space and fighting aliens but the similarities to his own life were undeniable. Adventure and excitement, a man you could always count on to save the day and his worthy companion. That's when he started to feel uncomfortable, though. When he thought about the Doctor's companions. Plural. He got through them pretty fast and John had only been living with Sherlock for, what, two years? Maybe his time was nearly up and that wasn't something he could bear to think about.

It was five past six and John was surprised by two things. The first being that he hadn't been dragged off to the other side of London to solve a crime, meaning that he wouldn't have to watch his show on the laptop for once. The second was that Sherlock was also sitting down, seemingly ready to watch television with him. John usually watched Doctor Who alone; his flatmate wasn't particularly interested.

"I just want to see what the fuss is about, John," he explained as he wrapped a blanket around himself and sat with his knees to his chin. "I can't move for people babbling on about it all day and all night. It's annoying. I may as well take the time to see if it's worth it." John gave a short laugh before realising that actually, it might be a bit embarrassing to watch this show with Sherlock. It's quite silly, he thought, as he wrinkled his nose. And most things are solved with love and kindness. His friend would balk at that. Science! Reason! Logic! Anything else made his head squirm.

The opening titles started and while John initially reigned in the urge to sing along, he quickly decided he didn't care and he was going to do it anyway. He had no problem walking around the flat half-naked in front of Sherlock, after all! This did seem a little more personal, though.

"Dum de dum, dum de dum, dum de dum, doo wee ooooooo, ooo ee ooooooooo …"

"John, what on earth are you doing?" He sang louder. The detective smiled to himself – it wasn't often that he saw John so playful. They shared a grin.

"So he travels through time and space …"

"Yes."

"In a spaceship that's bigger on the inside than it is on the outside …"

"Yes."

"With a companion."

"Yes."

"But from what I've gathered the companions chop and change every so often. Why would you do that?" John sighed. The show had finished half an hour ago and he'd been trying to explain its premise ever since. The only reason he hadn't yet walked away was because he was pretty surprised, but also pleased, that his friend was taking such a keen interest.

"I know you don't tend to pay much attention to popular culture but this stuff has been common knowledge for just under fifty years, Sherlock! Sometimes the Doctor and his companion are forced to part, sometimes he or she realises that it's time to start a life of their own..." Sherlock's eyes flick up at this but John doesn't notice. "Lots of reasons."

"Hmm."

The next afternoon the two of them were embroiled in a case which, as ever, involved a lot of running. They leant back against a wall stopped for breath after catching their man and leaving Lestrade to arrest him. After a while the consulting detective spoke.

"Is this just an interlude for you, John? Between the war and starting a life of your own?"

The ex-army doctor was completely taken aback.

"God, no. Where did you get that idea?"

"Last night, I … And it would make sense, I wouldn't blame you." His voice was even deeper than usual, as if he didn't really want to be heard at all.

"No, Sherlock. This is it. I'll be honest, for a while I did think about settling down with someone and starting a family but that's not … that's not what I want. I can't imagine life without you and I don't particularly want to, either. To tell you the truth I was sort of scared that you'd … get bored with me eventually. That you might find a new, well, companion I suppose." He caught Sherlock's gaze quickly enough to see the hurt in his eyes before he regained his composure.

"Ha! As if I could ever find anyone else who puts up with me as well as you do. And why mess with a winning formula?" He gave a cheeky smile. "Besides, John …" His voice deepened again. "I only want you. I only ever will want you." He looked his friend square in the face as he said this to make sure John knew that the sentiment was completely genuine. The shorter man understood perfectly and was visibly moved, his eyes softer than Sherlock had ever seen them. Subsequently he stepped forward, gently grabbed Sherlock by his curls and kissed him on the forehead. He then moved so that their foreheads were pressed together and their noses were touching, a position from which he did not move for a full minute and during which Sherlock saw fit to wrap his arms around John's waist. They pulled apart gently before smilng sheepishly at each other and heading home.