Work Text:
Amazingly enough, John notices it first.
It must be something to do with combat instincts, or paying attention to nagging feelings despite any amount of contradictory evidence, or just paranoia. Whatever it is, it boils down to this: something is wrong.
John puts down his paper and frowns at the kitchen, where Sherlock is reading an old book they found at a crime scene last week. Everything looks normal. There's nothing John can pin down, just a creeping sense of unease. Maybe it's a gas leak. Or a heart attack. He's not sure what it says about him that either one of those is more preferable to the imaginable alternatives. Probably no one should have worse imaginable alternatives.
"Sherlock."
"Hmm?" says Sherlock, without looking away from his book.
"You're not experimenting with anything barmy, are you?"
He frowns. "Difficult to say."
John narrows his eyes. "What do you mean, 'difficult to—'"
"I don't know, what are the criteria for determining whether something is taxonomically 'barmy'?"
John sighs heavily and counts to ten. "Anything…mind-altering."
"Mm, barring any as-yet undiscovered psychotropic properties of the mold spores in old books, no."
John grins. "Sounds like a fun night out."
Sherlock snorts out a laugh and flashes him a brief smile before turning back to his book. Almost reassured, John shakes his paper open again.
There! His head whips sideways and he's instantly on alert. He lowers the paper slowly and sets it on the table.
"Sherlock."
"Mm?"
"Come here."
"But—"
"Now!" The command is like a whip-crack. Sherlock obeys out of instinct, shutting the book and moving slowly and cautiously to John's side, like a wary cat. He may not buy into instincts or gut feelings, but he believes in John.
"What is it?" he asks in hushed tones.
"There's something in the flat," John says.
Sherlock snorts. "Please. It's probably a stray cat, or—oh God!"
Something small and dark darted past him, close enough to ruffle his dressing gown, and disappeared in the mess under the desk. John jumps to his feet and pulls Sherlock behind him.
"What in hell," he breathes.
"I don't know," Sherlock says, voice shaking. "I—I don't know."
"Feel it?"
Sherlock nods.
It's cold. It was worst when the shadow passed over the two of them, but it's still there, radiating an eerie iciness. John's stomach is churning and his hands are tingling and the tiny hairs on his arms and neck are standing on end and there's nothing there but there's something, by God, and it is not safe.
"Gun in there." He jerks his head toward the stairs. "My room."
"You think it'll help?"
"I think it won't hurt."
"Slowly, then."
John taps Sherlock's arm, indicating that he should move first. Together, they back towards the stairs, keeping their eyes on the corner.
BANG.
Sherlock's bedroom door slams shut. John doesn't know what Sherlock's doing, but he's running, running up the stairs and into his bedroom and to his bedside table, pulling his gun out, and loading it with shaking hands. Sherlock is mounting the last two stairs when his toe catches the top step. He trips, grabs for the railing, and—
BANG.
John's door slams shut.
He runs to it and the knob is sticking. On the other side of the door, he hears Sherlock gasp.
"God, I—oh my God!"
Then there's a horrible sound like seams ripping, and Sherlock's voice making sounds like he's choking, and John is kicking at his door and it's not giving in, and something is climbing down Sherlock's throat. John screams Sherlock's name, backs up three steps, aims at the doorknob—Sherlock is screaming now, screaming like John hasn't heard since his worst nightmares of the war—and fires.
It goes silent.
John freezes for perhaps a second, then runs to the door and pulls it open.
Sherlock is standing at the top of the stairs. There's a thin sheen of sweat on his face and he's perhaps breathing a little hard, but he looks…normal.
"What in fuck," John pants.
Sherlock frowns. "Pardon?"
"Where did it go?"
"John, what are you—"
"The fucking thing that was trying to FUCKING KILL YOU, that's what!" John bellows.
Sherlock looks genuinely taken aback. He looks around, taking stock of the situation. "I…there is certainly something…off," he says uneasily.
John laughs a single high, panicky laugh. "That's for fucking sure."
Sherlock looks around again. "I can only assume that—John!"
John does not respond. He is clutching his throat. So is it.
It came up behind him, and it has its icy fingers—are those fingers?—around his neck, squeezing down too hard for him to make a sound. Sherlock starts to rush it, but then stops, standing stock-still and calm at the top of the stairs, watching John suffocate.
Darkness is creeping into the edges of his vision, and the cold is crawling from those fingers down his chest and up into his face. He struggles feebly, tries to kick, butt, elbow, anything. Either he misses, or there is nothing there to hit. He tries to choke out Sherlock's name.
The last thing he sees is Sherlock's mouth curving into a thin, satisfied smile, and then John sinks.
"I think they'll do nicely."
John blinks.
For a moment there, he felt as if—but no. He lowers his paper and looks to Sherlock in the kitchen.
"Sorry, what was that?"
"Mm?" says Sherlock, without looking up from his book.
"I thought you said something."
"Mm, no."
"Reading aloud, maybe?"
Sherlock scoffs.
John shrugs and starts to bring his paper back up. He twiddles his toes. There's a strange chill in them he can't quite shake, like after you've come back in during the dead of winter. The joys of age and poor circulation, most likely.
In the kitchen, Sherlock is still reading, but he is not looking at the book. He is looking at John, and smiling.