Disclaimer: BBC and Whedon own what you recognise.

AN: This concept came to me as a crack fic but then somehow evolved into something more (I blame gender studies classes at Uni), which then evolved into a study of John and Sherlock's relationship. Let me know what you think.

Smoke and Stardust

"But this is completely irrational," Sherlock says, frowning, before deftly staking a vampire to his left.

John snags two more with a quarterstaff. "Irrational or not, it's real."

"But - "

"I told you, 'Into every generation a slayer is born: one girl in all the world -'"

Sherlock's face twists peculiarly, as if he doesn't know what to say. To cover up his confusion, he kills another soulless creature of the night.

"Female, then?" he settles on finally when the last vampire is dead.

"Ah. About that," John says uncomfortably, brushing dust off his jacket. "I'd've told you earlier only I thought you'd already deduced from...well...that time you walked in on me reading that 'What's Happening to My Body?' book for girls."

Sherlock is silent for ten seconds, eyes narrowed in thought. Then, "A history in the black arts coupled with your recent reconciliation with an ex-girlfriend of Harry's - the ginger Wicca of formidable talent and occasional bouts of sadistic humour," he declares triumphantly.

"I knew it was a mistake to bring you round my sister's place for Christmas," John mutters, squirming in vague discomfort as he readjusted his training bra.

Sherlock follows the movement then meets John's eyes. They stare at each other intensely for a moment.

"Does this change anything?" John asks, a note of anxiety creeping into his voice. "Not just the...different bits...I mean, any of it. The Slaying, the - " He clears his throat and cuts off awkwardly.

Sherlock frowns again. "Of course not," he says, in his you're being disgustingly dense voice. "You're still you, no matter what the world perceives."

He pauses, then adds, "But if you plan on bringing your work home with you, do text in advance so I have time to bring out my finest stakes. I did love tonight's entertainment and would enjoy a repeat performance but I'd hate to be caught unprepared for our guests. That just seems impolite and you're always telling me to work on my manners."

John releases a breath he didn't know he'd been holding and grins like an idiot. In response the corners of Sherlock's mouth twitch, and though he doesn't smile he does allow himself a smirk - and it's normal and it's mocking and everything John needs.

"Right then," the dark haired man says easily. "Let's see what the Chosen One makes of our newest case." He rubs his hands together with predictable, inappropriate glee. "Triple homicide, each victim cut in half - one half present and accounted for but the other half missing, possibly discarded but more likely stored, preserved somewhere - but why? - coordinates of each crime scene show the bodies were found at strategically placed points, each 21 miles apart from one another in near-perfect triangle formation (obviously defying the laws of human error) thereby forming near-perfect 60 degree angles - brilliant!"

"Sounds like wanna-be Satanists taking their hobby a little too far," John argues.

"This is a Hellmouth, apparently, if this entire evening is to be believed," Sherlock replies dismissively. "Just as with Existentialism and Celebrity Big Brother, I think we can safely conclude that on a Hellmouth everything is taken a little too far."

With that he's off again and onto something new, and thoughts are erected and discarded by the second and John basks in the firing of synapses, the precision so intense it borders on ferocity, the wolfish grin that speaks of conspiracy and enjoys the macabre just a little too much -

And the utter normalcy of it all is pure magic, smoke and stardust, half-cocked revolvers and cinnamon cigarettes and just the slightest hint of cynanide ice cubes in spiked lemonade, and John is loving every minute of it. Because there were so many reasons for a schism, so many ways this could have collapsed - but the world (their world...his world) is just as he left it in that amorphous Before: things remain the same between them, just now with more stabbing and different...kit.

And Sherlock sees this, and John sees Sherlock with brighter colours and softer edges.

Sherlock has always been a genius, yes, but his brilliance comes from observation and fact. His grasp of common sense, emotion and intuition is limited: these are subjective creatures, resistant to proof and therefore impractical in his eyes. But his earlier answer (and the immediacy of it) had not been born of deduction. They had come from a deeper place, a tremendously subjective one Sherlock would never admit to.

Understanding. Connection. Personal conviction.

John smiles. He pockets his stake, grabs the quarterstaff and steels himself for the long night ahead, of being rational and not letting Sherlock play too rough with the corpses.

Then with a laugh and a wolfish grin of his own, he follows in the wake of that billowing coat.

AN: Thanks for giving this a shot. I'd love to hear your thoughts!