AN: unbeta'd. Pretend it makes sense :D
The first time it happens it's out of sheer curiosity.
It's been a month since the pool incident and John is out with Sarah for what Sherlock deduces will be the last date they ever go on. Mrs Hudson is out and there hasn't been a really interesting crime in forever.
It's 6 o'clock, just getting dark and Sherlock is roaming around the flat like a caged animal. Nothing to do, boring, dull.
He finds the crumpled piece of paper under a mound of scrawled notes about tobacco ash that he has yet to type up and smirks a little. Jim-from-IT's-number. Out of pure interest he dials the number and is faintly surprised when the phone is answered after two rings with a growled, "What?"
"Do you answer your phone like that to everyone or just the ones you want to kill?" Sherlock asks smoothly.
"Oh. Oh," Moriarty giggles. "Why, Sherly, I wasn't expecting you to call."
Sherlock wrinkles his nose at the use of Sherly. His mother was the only person who dared to use it. "I was curious and I was bored." He says stiffly.
Moriarty laughs again, just too high pitched to sound normal, but then there was nothing normal about Moriarty at all. "It's alright, pet," he purrs. "You don't need to make up excuses for me. I know you can't resist me."
Sherlock wants to deny it but he knows there's no point. Moriarty fascinates him. He's unlike anyone Sherlock's ever met, ever will meet. He could feel it when he first met the man, like electricity in the air, thrumming through his veins, his brain exploding in joy. He's like me.
But at the pool John had been there. John had been in danger. Dear, brave, honest John.
But John isn't here now.
"And you can't resist me." Sherlock replies.
"Oh, you are still there? I was beginning to think I was talking to myself!"
Sherlock pauses because what he's about to do is wrong; his inner-John reminds him. But Sherlock's never been one for listening to his inner-John when John isn't around so he says, "Are you busy at the moment, Jim?"
Moriarty makes a sound like an excited puppy and Sherlock smirks despite himself.
They meet at a posh hotel and as Sherlock gets out of the black cab he notices the numerous security cameras around the place. He makes sure to smile for Mycroft and doesn't feel guilty at all.
Moriarty is already in the room, perched on the bed a glass of scotch held delicately in one hand. He's gazing in to the distance and gives no sign that he's aware of Sherlock's presence. Sherlock can almost see the gears in Moriarty's wonderful brain whirring, clicking into place and it's delicious.
"I always pictured you as more of a cocktail man," Sherlock drawls.
Moriarty's dark eyes slid onto him and the shorter man grins slow and feral. He downs the drink in one and places the glass carefully onto the bedside table. "I did tell you I'm changeable, didn't I?" he says looking predatorily at Sherlock.
The feel of that liquidly dark gaze on him does funny things to Sherlock's head. He feels exposed, vulnerable. He shivers and sits down beside Moriarty.
For a moment the world falls away and the two men just stare at each other. As Sherlock eyes Moriarty up his mind soaks up every piece of information it can. Late twenties, early thirties, psychopath, faint scars on wrist, possible previous suicide attempt, slightly defensive body language...and he knows Moriarty is doing the same.
Their eyes meet at the same time.
Two of the most brilliant minds in the world.
Sherlock raises one hand and brushes a thumb across Moriarty's lower lip and Moriarty looks faintly surprised that Sherlock's moved first.
"Dear Jim," Sherlock says, the words tumbling from his lips thick and heavy. He touches Jim's cheek, Jim closes his eyes. "Dear Jim, I'm so absolutely, incredibly bored. Can you help me?"
Moriarty's eyes open and they're bright with malice and lust. "Oh, I think I could do something about that." He lilts, grinning.
And Sherlock smiles back.
Sherlock leaves that evening with the coppery taste of blood fresh in his mouth and bite marks all over his neck, his mind is blissfully blank and he's already planning next time.
Later, much, much later when Sherlock glances at his reflection and thinks about how the blue of his bruises match the blue of his scarf he realises he's slipping. It may not be drugs this time but that doesn't mean it's any less dangerous.
He thinks about what John would say, wonders if Mycroft will try to stop him, wonders if Mycroft will tell John. But even as he thinks those thoughts there's a dark being with Jim's voice lurking in the back of his brain thinking about how many colours he could make on Jim's skin.
He hushes the voice because there's John to think about and a serial killer (well a soon to be serial killer) on the loose right now to occupy his mind.
But he knows when that's over the darkness, the dullness, the greyness of mundanity will creep back in and all he'll think is JimJimJim.
The second time it happens Sherlock takes control.
Last time it was all Jim and chaos and teeth and pure, unadulterated need. This time Sherlock holds Jim's wriggling body down and paints his skin with mauves and golds and blues and greens. He watches for every gasp and whimper and growl of need, he watches for every time Jim stiffens or arches or tightens his grip on the sheets.
He watches and Jim lets him.
Jim lets Sherlock map his body, every sweet spot, every mark, every scar (because Jim has so, so many). And when Jim twists and howls beneath him and Sherlock shudders he finds himself making a hazy note to ask about everyone of those scars (not that he can't tell where each of them came from). Belt buckles, extension cord, cigarette burn, bite mark, cut mark, rope burn...
After the third time, fourth time, fifth time, Sherlock starts staying the night and one night he finds himself watch Jim sleep.
Part of him laughs at himself the other part marvels at how human Jim looks asleep. He looks small and young and vulnerable.
He's in bed with the devil but Sherlock's never been an angel, never wanted to be one anyway.
Sherlock's hands wander up to clasp Jim's neck of their own accord. If he squeezes tightly Jim will be gone, like a candle snuffed out. No doubt one of Jim's many snipers will pick Sherlock off in a heartbeat if he actually does kill Jim, though.
His inner John lectures him about how many lives he'll save and how much better off the world would be but the inner John doesn't want him to kill Jim. The inner John just wants Sherlock to stop, think about it, turn him in. (Even inner John knows that no prison will be able to hold James Moriarty though.)
He knows he can't kill Jim though. Killing Jim would be like destroying himself. Destroying the one person who understood.
When Sherlock looks at Jim he can see everything he might have been. If he hadn't had Mummy and Mycroft and John and Lestrade and Mrs Hudson. If he'd had a life like Jim's, a life that mapped itself onto his skin in more than just connect-the-dot-track marks. He looks at Jim and wonders who he'd be if they'd met before...before Jim chose the devils and Sherlock chose the angels.
His hands unclasp from Jim's throat and he almost wraps his arms around Jim's body.
It's not about love. Love doesn't exist, not for people like him and Jim. It's a need. A deep emptiness inside him that needs Jim closer.
(Inner John's voice gets fainter.)
Instead he stands up, dresses and leaves. In the morning Jim will wake up in cold bed and Sherlock's glad they never talk, Jim wouldn't ask anyway.
Sherlock looses count of their meetings after around their fortieth.
But this one is different.
Jim is late and when he does appear his suit is torn and rumpled, his hair is a mess and his lip is torn and bleeding. He looks at Sherlock like he wants to tear him apart and Sherlock lets him.
Afterwards Jim bites down on Sherlock's shoulder hard enough to draw blood. "I hate you, Sherlock Holmes," he mumbles. "I hate you, you and your stupid face."
Sherlock almost laughs because that's honestly the most human thing he's ever heard Jim Moriarty say. But then he realises what Jim is really saying and he finds himself running a hand through Jim's sweaty hair and saying, "Likewise, Jim."
When he wakes up Jim is sitting across the room from him. "You're going to meet a friend of mine today." He says solemnly. Then he leaves.
Irene Adler is everything Sherlock would have expected of Jim's friends. But it's when Mycroft mentions Jim that Sherlock realise why Jim looked so distressed.
They meet again that night. It's not arranged but they both know the other will be there.
The lights are off and it's storming outside, Sherlock chuckles. Apt.
Jim is sitting in the dark. "Your brother is after me." he says.
Sherlock sits down on the bed, "Don't pretend you didn't want him to. What have you got planned Jim?" he knows Jim won't answer. Outside of their meetings they still play their little game as usual.
Jim giggles, "Oh, Sherlock. You'll love it; I just need a few more puzzle pieces."
Sherlock half smiles and hopes that Jim's content to pretend nothing's changed, but of course, he isn't. "People know, Sherlock." Jim says quietly.
Sherlock closes his eyes and sighs heavily. "I know. What do you want to do?"
"They're going to try to hurt you, kill you. To get to me."
No one ever gets to me, Sherlock's mind echoes. He smiles again and chuckles lightly. "No one ever gets to you, Jim."
Jim laughs weakly. Weakly. There's never been anything weak about Jim Moriarty. "I could leave," Jim says and as he does Sherlock's blood freezes.
"No," he says so suddenly he almost feels Jim jump in surprise.
"What?" Jim asks after he's recovered, voice quivering with anticipation and just a hint of glee.
"You can't leave, Jim." Sherlock says through gritted teeth.
"Wh-hy?" Jim prompts sing-song.
Sherlock sees a movement out of the corner of his eye, turns, grabs Jim by his shirt front and yanks him onto the bed where they land a tangle of limbs. Jim yelps in surprise and Sherlock presses them as close together as he can. "You know why." He hisses.
Jim giggles, face buried in Sherlock's chest. "I told you I'd burn the heart out of you."
You're not dead yet, Sherlock thinks. "You did, but was this part of the plan?"
"No," Jim admits quietly.
They lapse into silence and the only sound that fills the room is the soothing rhythm of the rain pattering outside.
"Come with me."
It's said so quietly that for a few moments Sherlock is sure he has imagined it. Sherlock looks at him and Jim looks back.
Jim's eyes go blank. "You choose them." he says slowly.
There are a million things Sherlock wants to say but they tangle themselves up trying to get out of his mouth and he finds himself speechless.
Jim sits up and leaves without a backwards glance.
When they're exposed to the gas he sees Jim. Of course he sees Jim.
Beautiful, terrifying Jim. But it's not his Jim (when had he become his Jim?) it's the Jim that he saw leave that hotel room. The one with nothing behind his eyes.
He doesn't see Jim again until the trial, Jim is all game and so is Sherlock.
There's only one break in character.
"I felt we had a special something," Sherlock says, watching Jim carefully.
Too everyone else Jim inclines his head and nods. To Sherlock Jim screams wordless rage. I will burn the heart out of you.
Sherlock closes his eyes briefly because inside he's drowning. JimJimJimJim.
He glances at John and it's like being thrown a life line. John makes him human.
When he realises Jim's new game he's absurdly impressed because it is brilliant.
Jim Moriarty peeks at him from behind Richard Brookes' hands and Sherlock can't help but smile. Genius. For a few brief moments he doesn't care about anything but Jim and Jim's mind and Jim's plan and Jim.
And that terrifies him.
He knows he's going to die.
He's accepted that.
He wonders how Jim will cope with him gone.
He wonders if Jim will care.
He wonders how John will cope.
How Mycroft will cope.
How Lestrade will solve any crimes.
With him gone Jim will probably kill more people, there'll be no one to stop him. He'll get to John and Lestrade and Mrs Hudson and eventually Mycroft.
And then there's Molly. Sweet, little Molly the morgue girl. Always fawning over him.
And he knows what to do.
He phones Mycroft.
He finds himself standing on a roof silently begging Jim to understand. Please, he thinks.
Jim opens his eyes and he's smiling and half-crying. "Bless you, Sherlock Holmes." He says.
Sherlock almost cries with relief, Jim's understood.
Jim pulls the fake gun from his jacket and Sherlock turns to the building ledge.
He says goodbye to John and it almost breaks him, it almost makes him want to die for real. But he can't. He's made a decision. A decision that will save lives.
He thinks John would be proud.
He meets Jim when he lands in New York.
Sherlock's cut his hair and straightened it and dyed it blonde and in the mirror he looks impossibly like his father. He's not Sherlock Holmes anymore. His passport says "James Stewart." He thinks Mycroft might have picked that name deliberately.
He almost doesn't recognise Jim in casual jeans and hooded top. He strides over to him and smiles, holding out his hand, "Jamie Stewart." He announces.
Jim grins and takes his hand. "Tommy McGann."
Jamie Stewart holds Tommy McGann's hand as they leave the airport.
Sherlock Holmes and James Moriarty laugh about it later.