It begins when Moriarty saunters close, his voice a disquieting modulation between amusement and animal rage. “I will burn you,” he explains, calm as you please, then snarls, “I will burn the heart out of you - ”
And Sherlock sees it then, the flat dark discs of his pupils, the slightest staining of a flush under his skin, invisible unless you know to look for it. He observes the pink point of his tongue swiping over his lips, once, twice. His eyes dart lower.
Oh. How dull.
But not without its uses. And this is what happens next: Sherlock is already working out a dozen newly plausible exit stratagems built around this revelation. As his mind works, swift and clinical, he’ll play at nervousness to buy time - ostentatiously adjusting his grip on the gun and shifting his stance, just barely tightening his jaw. In the next few minutes he will put a plan (he doesn’t know what it is yet, but he will momentarily) into motion, and it will be fine, it will be perfectly fine, and John will stop looking as though all his ghosts have come back to haunt him at once.
He feels curiously warm.
John is staring at him. Possibly. Suddenly it’s difficult to tell, like he’s seeing the world through a misty localized fog. He lowers his arms. Feels the gun leave his fingers, the reverberation of its clattering impact against the floor. His feet are taking him closer to Moriarty in deliberate, measured steps, and there’s a possibility that John is yelling Sherlock and what are you doing; but he is so far away, and the obvious solution, the only logical conclusion, is right here.
Moriarty stands in sharp relief against the fuzziness slowly overtaking Sherlock’s field of view.
“You’ll let John go,” Sherlock says sharply, not a request, and is quietly surprised at the evenness of his own voice.
“Yes,” coos Moriarty. He reaches out with one long-fingered hand, grasps Sherlock by the jaw and turns it slightly to the side, appraising, affectionate. “Oh, yes. And you’re coming with me, Sherlock Holmes.”
The interior of the car is all velvet gloom and pungent leather. Moriarty sits opposite Sherlock, little more than a shadowed outline, his teeth gleaming tiny and sharp in the darkness. The partition which separates them from the driver is firmly shut; they are utterly alone.
Moriarty hasn’t moved yet, but the weight of his gaze is palpable. Sherlock’s heart quickens, sudden and deafening. Something in him swells and suppresses his breath - fear, or excitement. Smoothly, almost soundlessly, the car trundles forward. It occurs to Sherlock that he should probably be more worried about where the car is headed, and at that thought he has to suppress a chuckle. He wasn’t worried when the cabbie took him for a ride, and he isn’t worried now - because, really, this is just too easy. People are so maddeningly predictable, so blandly alike in their base desires. Even, apparently, James Moriarty, who is clearly human above all else.
They pass under a streetlight, and for a moment Moriarty’s face is illuminated, sickly white and pointed. And - yes - his pupils are still dilated. Sherlock’s hand tightens unconsciously around his seat belt buckle. He feels distinctly like prey, a jackrabbit speared on the gaze of a crouched predator. He narrows his eyes slightly. Why won’t he speak? He should be loquacious; evil genii generally are, and throughout the poolside encounter, Moriarty had played the unhinged cardboard villain to a T. But now it’s as though a switch has been thrown, all that flamboyant villainy gone and channeled into an unsettling silence. There’s something running below the surface here, some key piece of information he’s missing, but what, what?
“Not a word for me, Jim?” asks Sherlock at last, deliberately coquettish. The panic of John in a furred green jacket no longer relevant, he slips effortlessly back into the game. Cat and mouse. Go on, he thinks, give the ball of yarn a swipe. “And I thought we’d been getting along so well.”
He waits for a pout, a coy response - Why, you great brute! Can’t you see that I’m shy?
It doesn’t come.
Moriarty moves with a speed that is, frankly, terrifying. Within the space of a blink, there are hands on his chest, knees bookending his thighs, mint-scented breath on his skin. Eyes, incandescent in the dark. Unconsciously, Sherlock presses backwards into the seat, a useless defensive mechanism. He half-expects Moriarty to flick out a serpentine tongue and lick at his eyeballs.
He does something far worse.
“Oh,” breathes Sherlock as Moriarty’s mouth falls open, as he unsheathes a pair of pristine ivory fangs, as he hisses, low and hungry. What on earth -
“Shh-shh,” says Moriarty, cupping him gently under the ear, thumb fitting into the notch above his Adam’s apple: a hair’s breadth away from a stranglehold.
The terrible fog is creeping over him again, stronger this time, tendrils licking into his mouth and leaving a film over his eyes. Moriarty's eyes burn a sickly yellow through it all, two spots of fire, and he can't move for fear and bewilderment.
"You - you can’t be serious," he gasps. "This is preposterous, Moriarty, exactly what do you intend to accomplish by dressing up like a child - "
"I thought I told you to be quiet," says Moriarty, and to Sherlock, to his utter dismay, shuts up.
Moriarty trails the soft pads of his fingers up past Sherlock's ear, over the aristocratic bones of his cheek and the arrogant bridge of his nose. His nostrils flare, nearly imperceptibly. "Oh, but you are pretty, Sherlock," he breathes. "That fine white skin, those delicious eyes. I always wondered how you did that, made them change colors in different lights. At first I thought you were a witch. Met quite a few of them in my time. Vain as peacocks, the lot of them."
He tilts Sherlock's head to the side and dips in, runs his nose up the marble hollows of his neck. Just barely touching.
"I've always wondered," he whispers harshly into Sherlock’s ear, "what this precise spot might smell like. Right behind the ear, hidden by your hair, where no one can see unless they get up close - as close as we are now. Isn't this lovely, being close? Isn't it, my dear?"
No answer. Faster than blinking he jerks up, hisses into Sherlock's face, "Isn't it?"
For the first time in his life, Sherlock is absolutely speechless. Moriarty grins, feral. "Of course - I'd forgotten. It's hard to think, isn't it, under my influence. Sorry about that. Well, I'm actually not, really. But I suppose it's a pity, as you do have the most delectable voice."
Sherlock finds it. "Stop this now, Moriarty," he rasps.
As Moriarty closes the tiny quivering inch between them, he whispers, "Oh, my dear. I’ve only just begun."
There’s no heat in the kiss, no passionate intent; it’s dutiful, like a red-inked stamp or the perfunctory flash of a cattle brand. This kiss is a coin frozen on a winter sidewalk, two sides cracking under a sheen of ice and buckling inwards. Moriarty breaks it after a moment, dry-lipped, expression like a knife. He reaches for Sherlock's left wrist and brings it up beside their faces, inspects it with the air of a man surveying someone he is about to fuck. His breath is frosty against the sensitive skin, and for a second Sherlock's body breaks free of the invisible force keeping it in stasis and gives one long, luxurious shudder. At this, Moriarty makes a low, almost pained noise, and sinks his fangs into the ulnar artery.
The world seems to slow to a shuddering halt. Sherlock has no idea what his face must look like; he casts his eyes wildly about the cabin of the car, feels his breath coming quick and panicked. It should feel like his life is draining slowly out of his wrist, but it doesn't - more like a mass exodus of vital energy from his entire being. He has never known such pain. The sickening hypnotic miasma thickens, in his belly, in his nostrils, in his mouth, dizzying and sour. His heartbeat is a brutal echo in his ears. It nearly drowns out the hungry, steady slurping sounds Moriarty is making. Nearly. He feels a single trickle of blood roll down the incline of his arm.
Moriarty pulls off what seems a lifetime later, lapping up the trail of leaked blood with one thorough lick, his eyes never leaving his victim's. Sherlock slumps uselessly against the licorice-dark leather seat, little more than a pale trembling streak. His pupils have gone wide and dark.
He is terribly, humiliatingly hard.
Moriarty drags a (shaking, Sherlock notices dully) hand across his mouth and sucks a droplet of blood off the blade edge of his palm. He lets his fingers fall to rest on Sherlock's lips and whispers, breath hot now, "Yes." Then they're kissing again, and Sherlock tastes the salt and copper of his own blood on Moriarty's tongue, feels the needle sharpness of those fangs pierce his lips. He whimpers into it, confused and desperate.
Hours later, John catches Sherlock's limp body as it flops through the doorway of their flat. It's unclear which of them is trembling more fiercely.
"Oh, God, you're okay," John gasps, clutching him tightly to his chest as they both sink to the floor. "You're back. You're okay. Fuck, I thought - All right, breathe, breathe, just relax - " His hands are cool on Sherlock's cheeks, thumbs rubbing in soothing circles. Their foreheads knock gently together and they breathe, tangled together at the edge of the carpet, the door still cracked open behind them. They breathe.
Later, after frantic questions (what happened, you’re white as a sheet, what were you thinking, what came over you?!), after sloppy hurried mugs of tea, after John’s hands drawing a dark wool blanket solicitously around his shoulders, Sherlock sits straight-backed and alone on the sofa. Outside, London at night hums and pulses, all copper veins and fogged undertones. The low buzzing rhythm echoes in his body. It whispers in the lines of his arms and in the curvature of his neck. Alone in the darkness, Sherlock tries to stop trembling.
He scrabbles blindly under the cushions and comes up with a lone nicotine patch, which he slaps haphazardly on his wrist, just above the barely-visible pinpricks at the base of his palm.
Two minutes later, he tears it off with a snarl of frustration and flings it across the room. He bites his lip and digs his blunt fingernails into the skin of his wrist.