A/N: Written for the prompt: Sherlock spontaneously combusts on a regular basis. It's no big deal.
Title comes from the Bible (Job 5:7) "For man is born for trouble, as sparks fly upward." It seemed like quite a Sherlockian sentiment
Chapter 1
"I play the violin, sometimes I don't for talk for days. Oh, and occasionally I spontaneously combust."
"What?"
"Prospective flatmates should know the worst about each other." The man says, raising his eyebrows as if nothing he'd just said was the slightest bit unusual. John's brain stalls struggling to catch up.
"I've got my eye on a little place in central London. Between the two of us we should be able to afford it."
"So.. that's it then?" John says. "We've only just met each other, we don't even know each other's names and we're going to look at a flat…?"
The man smiles, and rattles off an unnervingly accurate assessment of John's career history, health problems and psychological status. John is just pausing to draw breath when the man swoops away from them, pulling on a long black coat as he goes. "The name's Sherlock Holmes and the address is 221B Baker Street." He winks and sweeps out of the door, a whirl of coat.
John looks at Mike, who is looking at him with a peculiarly understanding smile on his face.
"Sorry," said John. "Did he say spontaneously combust?"
Mike grins. "You don't know the half of it, mate."
The first time John sees it happen is in the restaurant, after the whole business with the cabbie and Roland-Kerr educational college. They are waiting for their order to arrive, both still buzzing slightly with adrenaline. John still has the smell of powder on his fingers, the ringing of the shot in his ears. Sherlock is leaning back in his chair, pale eyes glowing as he recounts his conversation with the cab driver. Actually all of him is glowing, John realises, a peculiar pale light shimmering over his skin. Sherlock gesticulates and suddenly there are flames, blue-white leaping over his palm.
"Jesus," John says.
Sherlock follows his gaze and frowns. "It's nothing to worry about."
John takes his word for it but he can't help twitching as the flames spread, fanning up his arms, and billowing around his chest. The flames deepen to a violet colour, veined with blue as they lick around Sherlock's pale neck. It is, John thinks, rather beautiful. Without planning to do it he finds himself lifting a hand, reaching across the table to touch.
"Don't," Sherlock says sharply and John drops the hand.
At that point their food arrives, a rustle of waiters moving between them and blocking Sherlock from view. By the time the last of the dishes has been set down the fire has gone out and Sherlock is spooning rice onto his plate, as if nothing had happened. John has about a dozen questions but judging from the sudden tension in his flatmate's shoulders they wouldn't be welcome. John decides to shrug them off and instead asks a question about the case instead. Sherlock glances up at him for a brief second and then relaxes visibly.
They pass the evening pleasantly, talking about murder and Moriarty and by the time they get outside again, into the sharp frost of the London night John has almost forgotten the fire. After all, John thinks dimly as he climbs into his new bed for the first time, it isn't like bursting into flames is the oddest thing about his new flatmate.
It doesn't happen often. Sometimes when Sherlock is deeply absorbed with working on a case John will notice a brief ripple of light running over Sherlock's body, like a gas fire on so low you can hardly see the flame. It rarely lasts for longer than a few seconds – blink and you miss it really.
Once they have an argument about John ditching out on a case to go on a date with Sarah, and Sherlock strikes out at the mantelpiece in frustration letting off a shower of sparks. Both of them stare for a moment, surprised, at Sherlock's hands before blinking and continuing with their argument.
All in all, it doesn't seem like a big deal. That is why John is surprised when, a few months into living with Sherlock, he arrives home to find smoke billowing down the staircase and the unmistakable crack of gunshots. John races up the stairs, three at a time, dropping the shopping. The atmosphere in the flat is choking, smoke stinging his eyes.
"Sherlock?" he calls, panicking. There is a noise and John turns to see Sherlock glaring at him. He looks positively demonic– his head and shoulders are surrounded by what looks like a fireball, a raging orange inferno putting out a stream of choking black smoke into the air.
"What the hell?"
"Bored!" says Sherlock and raises the gun (John's gun, he notices) and fires it into the wall.
John immediately forgets about the fire in the tide of anger that floods through him. "Right," he snaps, stepping forward. Sherlock's eyes widen as he gets closer and he jumps backwards out of John's reach.
"Don't come any closer!" he says.
"Put my gun down." John grits out, and to his surprise, Sherlock does, tossing with a lack of care that makes John wince onto the coffee table. John bends down to snatch it up, and then immediately drops it again, swearing. It is scalding hot.
"Christ," John says, cradling his palm.
"What did you expect?" Sherlock half shouts at him, flames roaring around his ears. John glares at him and goes to the sink to run his hands under the water.
Sherlock lets out a snarl and moves to the sofa, flopping down on it, pouting. The flames have subsided a little, reduced to a low smoulder. John sighs, counts to ten, then moves his hand out from under the tap, wiping it carefully on a cloth. He picks the gun up with the cloth, removing the ammunition and putting it carefully back in a drawer. When he looks back at Sherlock the flames are gone and the smoke is slowly dissipating. Sherlock is staring furiously at the ceiling.
"What was that about?" John asks.
"I told you," Sherlock snaps. "Bored."
There's something, John thinks, about the way Sherlock deliberately isn't looking at him. It reminds him of the first night in the restaurant – the only other time he's seen Sherlock combust. He sighs and decides yet again to leave discussion of the whole 'your head was on fire' thing for another time.
"So, you decided to take a shot at the wall, did you?" John says. "Not really on."
John thinks Sherlock looks a little relieved for a moment, but the expression is gone before he can be sure.
"The wall had it coming." Sherlock sneers.
"What about the Russian case?" John asks. He's learned that getting Sherlock to talk about crime is usually the one sure fire way to sweeten his mood.
"Belarus. Open and shut domestic murder. Not worth my time." Sherlock says dismissively.
Right. No go there then. "I'm starving. Anything in?"
As it turns out what is in is a human head, which apparently Sherlock sees nothing wrong with. He throws quite the strop about John's reaction to it, and then moves on to complain John's blog.
John has to admit he is a little hurt by that. He'd got the impression somewhere along the way that his admiration meant something to the Sherlock. If John was completely honest he might have spent his morning break daydreaming about Sherlock's reaction to the blog post. About the faint pleased look that might spread across Sherlock's face when he realised John had written about him, the same look that appeared whenever John complimented him or asked him about his methods. Apparently not.
"…Or better still, stop inflicting your opinions on the world." Sherlock finishes his tirade with a flounce of his dressing gown, turning away from John. John looks down on him with gritted teeth for a moment, and thinks: That's it. I was trying to help but you've worn away at my last nerve.He grabs his jacket and heads for the door.
"Where are you going?"
"Out," he replies grimly. To hell with all of this.
John goes to Sarah's where he spends the night on the sofa. Next morning she switches on the TV only for John to see the blast strewn remains of Baker Street.
"Christ," he says to himself in horror."He's actually done it."
As it happened the explosion wasn't anything to do with Sherlock or what John has privately started to refer to as his 'smoking habit'. Credit goes instead to criminal mastermind apparently obsessed with kitting people out in dynamite and setting Sherlock puzzles. The final person to be strapped into a bomb vest turns out to be John which, all things considered, John ought to have expected.
John's footsteps echo as he approaches the poolside. Sherlock is standing at the back of the room, a sheath of emerald colour flame surrounding him like a wall. He turns and the flame gutters as Sherlock's eyes meet John's, his mouth falling open.
"Evening. This is a turn up, isn't it?"
John watches as Sherlock blinks as if struggling to understand what's happening. "John, what…."
"Bet you never saw this coming," Moriarty's voice lilts in John's ears, and gritting his teeth John repeats him. "Take off the jacket."
John obeys slowly, Sherlock watching him. As he catches sight of the bomb vest a vein of pure scarlet flickers up from Sherlock's feet passing through the green wall of fire and disappearing.
"What would you like me to make him say next? Gottle of geer. Gottle of geer. Gottle of…"
"Stop that," Sherlock says, the wall of flame rippling again.
"Nice touch this the pool where little Carl died," Moriarty says in John's ear and John dutifully repeats it. "I stopped him. I can stop John Watson too. Stop his heart."
Sherlock's eyes travel to John's chest where the red point of light has appeared. The flames around him hiss quietly.
"Of course," The voice is no longer coming from the ear piece. John turns to see Moriarty slinking out of the shadows. "That would be rather a dull way for the little puppy dog to go. I'm sure you and I could think of something much better."
Sherlock stares at the man, who laughs.
"Don't you remember me? Jim from the hospital. I gave you my number. I thought you might call." Moriarty's head tilts. "Oh, but you are lovely like this Sherlock. Really quite… what is the word… incandescent. Is that all for me? Or is it Johnny here who's getting you all hot and bothered?"
John blinks, unable to parse the meaning of that sentence.
"I've given you a glimpse, just a tiny glimpse of what I've got going on out there in the big bad world, Sherlock."
Moriarty's voice drones on, but John is no longer listening. He's looking for a way out of this, and there obviously isn't one for him, what with the dynamite and snipers trained on him, but maybe there is for Sherlock if John plays his cards right. John takes one deep breath, waiting for a moment when Moriarty seems distracted and then throws himself sideways into the man, wrapping his arms around his face and chest.
"Sherlock, run!"
The fire around Sherlock grows into a long column, rushing upwards, the light making his pale face look ghastly. He doesn't move.
"I'm afraid you've rather shown your hand there, Doctor Watson." Moriarty says and John's heart thuds. A red dot has appeared on Sherlock's forehead. Sherlock's eyes flicker, and John stands down, stepping back from Moriarty. Moriarty curls a hand around his upper arm, not allowing him to move far away.
"Do you know what happens if you don't leave me alone, Sherlock?"
Sherlock curls his lip in what John is sure is feigned boredom. "Let me guess. I get killed?"
Moriarty's hand tightens on John's arm. "Kill you, Sherlock? Oh no. Not yet anyway. I'll burn you. I'll burn the heart out of you."
Sherlock's face shivers through the flames. "I've been reliably informed I don't have one."
A childlike grin spreads across Moriarty's face. "Let's see, shall we?" he says. He yanks John back and then shoves him hard towards Sherlock. There is a moment where John's eyes meet Sherlock's and he sees a look of utter shock in them. Then the flames are rushing in front of him, catching hold of the fabric of his coat, and hair.
The pain starts low like the pricking of a thousand needles, and until feels as though every inch of his skin is being ripped open. He hears someone screaming and realises it is himself – jaw open so wide he feels it might crack open.
The flames rush upward around him and John feels a burst of terror, a twisting horror deep in his chest. No, no, no, not John, please not John. Just when John thinks he can't bear anymore he sees a dark shape rushing towards him and he is falling backwards into the dark.