Sherlock does rather well, he thinks, in his flatmate's wife's absence, of making sure John remembers to eat regularly and gets to sleep at a decent hour. That is, until Lestrade calls him with a triple murder that's just been resurrected from cold case status by a new killing following the old pattern.

John is more reluctant than he'd like to accompany him, protesting that he hasn't called in to skive off work in over six months and he isn't about to waste his precious stock of days off to follow Sherlock around making notes and generally looking like a right idiot.

Sherlock pulls out the big guns – saying please, and adopting an expression reminiscent of a starving, wet kitten – and finally, John gives in, and they get a cab to the Yard, just like old times.

Just like old times indeed, he thinks gleefully, as they pursue the serial killer through the back streets and alleys of London; just the two of them and a madman, without any of the trappings that came along with Moriarty's syndicate. Just him, and John, and the night air cold and exhilarating around them.

He chases the man up a spiraling, rickety fire escape to the top of a tenement (where Parkinson thinks he's going, Sherlock doesn't know, because that particular tenement has a good fifteen meter gap between it and the surrounding buildings, and even he is not foolish enough to try and leap that distance), shouting to John to head around the back of the building, in case there is a second fire escape or other avenue of prepared escape from the rooftop.

He scrambles off the fire escape with a clang of metal and thud of shoes skittering on loose gravel and debris, and sees Parkinson skid to a halt at the opposite edge of the roof, whirling around frantically and waving the murder weapon, a nasty-looking antique dagger, in his direction.

Expecting the usual confrontation followed by the killer's surrender to the inevitable, Sherlock is not overly worried; he is quite able to escape the path of a clumsily-wielded weapon such as that heavy knife, and Parkinson has apparently nowhere to go.

But he barely has time to open his mouth in the usual confrontation, when a forceful gust of wind, wet and chilled from the Thames, whips about the tenement rooftop. Parkinson's arms windmill frantically, and he teeters wildly for a minute on the edge of the rooftop. Sherlock rushes forward, but he is too late; the man plunges over the side with a defiant scream that soon dies below. All he can see upon looking over the side of the building is the darkness of a barely-lit alleyway.

Tedious, he thinks in disgust, as he clambers back down the fire escape. He shoots off a text to Lestrade, asking him to bring along a cleanup crew, and walks in annoyance around the building to the back. What's left of Parkinson is on the concrete of a tiny, rather pathetic patio in the alley behind the building, and it's quite obvious that their work here is done.

He only realizes then, that he is quite alone bending over the rather gory remains of their serial killer, and he squints around in the dim light until he sees a small figure leaning up against the dingy brick of the building opposite.

"John?" he calls in annoyance, because what was the idiot doing while Sherlock was up chasing after their killer?

The alley's single dim street lamp is too far away, and so he pulls out his phone. The bluish light illuminates John's white face with startling, frightening clarity. His friend – because he is that much, as Sherlock would hardly jump off a building for someone who is of less consideration – is pale as paper, trembling and hunched into his short coat like he's seen a ghost.

Wait…

…jump off a building.

Idiot.

The harsh hiss of his self-deprecating swearing is painfully loud in the silence, and he holds the phone closer, his free hand closing on John's shoulder. John's eyes close briefly, forehead pinched and lined with stress.

"I'm sorry," he blurts, because it is the Good Thing to say, isn't it, even though it really is no fault of his? "I didn't think, John…"

"Not like you knew he'd take a dive off a roof, Sherlock." The words are barely audible, whispered into the gust of wind which has whipped again through the alley, carrying the stench of decay and blood with it. John's lapel flaps idly against his chest, as he hunches further into the inadequate jacket with a convulsive shiver.

"Thought I'd be past that, now. Evidently not. I…ngh." Like a marionette whose strings have snapped, John's knees suddenly give out, and it's luck more than skill that has Sherlock in the right position to help him slide down the wall to sit on the cold pavement, head between his knees.

"All right…it's all right, John." The words are trite by now, overused in the thousand apologies he owes this man for countless wrongs, and yet it is all he knows to say. He hastily struggles out of his coat and tosses it over John's hunched form in lieu of a blanket, because what else can he really do since he's rubbish at this whole comforting lark? He sits uncomfortably on the slightly damp ground beside John, and nervously picks at a loose string on his trouser-cuff.

John straightens up after only just a moment, though he doesn't relinquish the coat, only tugs it closer, shivering even with the added warmth. They sit there for a few minutes, silently watching the darkness of the night around them.

Sherlock's mobile chirps, the backlight of the small screen illuminating their faces in sharp contrast.

"Lestrade's on his way. Wants to know if you're all right, all things considered," he reads, and feels John's half-hysterical snort.

They sit in silence for a few more minutes, and he can feel John's shivering gradually easing, the tension disappearing between them slowly. They are not quite all right, perhaps will never be; how can they be, with what has happened.

John shivers again suddenly. "I may not be able to do this, y'know, Sherlock," he admits, mainly to the darkness and Sherlock's coat. "The whole. Uhm. Running over rooftops thing. Not for a bit, at least. Yeah, no. I still can't watch the Dr. Who finale."

He ignores the reference, because he has no clue what it means, but he can deduce enough to know what John's too embarrassed to say clearly. "Solid ground only for you then," he agrees, though he can make no promises that he won't use every method open to him to chase down a criminal.

He glances surreptitiously to his left just in time to see that John looks faintly ashamed, blushing in the pale light of his phone as he returns Lestrade's text.

"You know it was three months before I dared get back into a black cab," he blurts out without thinking, a rare occurrence.

"Six weeks before I could even stand to eat Chinese, Sherlock."

"I'd be perfectly content to never see a public swimming pool again."

"I have nightmares about glowing rabbits."

"I really, really despise fairy tales."

"I still have to rein in the urge to shoot your brother every time I see him."

"Nothing new there, then."

They both laugh, a short, breathy burst of giggles that is more reaction than genuine amusement, but it does the trick, and before long they are both relaxed, yawning as they sit against the brick of a filthy London tenement, heedless of the bloody corpse only meters away.

His phone chirps again.

"Lestrade?"

"No," he groans dismally, staring at the screen. Make John Go to Bed is the title of the alarm that winks cheerfully at him. "Your wife is going to kill me."