Ten minutes earlier
"Unless I jump. Complete your story."
"You've gotta admit that's sexier." Moriarty grins ecstatically, almost, and the grin is almost enough to finish Sherlock off right then.
He holds his breath, because he knows that the madman isn't finished speaking.
"You see, it won't end there. Because although you might actually live – even I don't know if your bones can withstand the impact –, you won't ever be left alone in your life. You'll be locked up on the spot, just because you didn't die, and when they find my dead body on the roof, well, that will do it for you, won't it? You and the rest of your kind, and darling Mycroft and all the rest. They'll hunt them down, find the rest of the missing monsters, and finally end them.
"Death, or life with shame and humiliation, Sherlock? Do you think you could stand that?
"And what about your friends, hmm? Ruin their lives with tragedy if you die, ruin them with association with you if you survive. I intend to win this no matter what, you understand, in whatever form I can, though I won't live to see it."
The laughs are coming in gasps now, thick and insane.
The detective blinks slowly, barely comprehending. "You – won't… live to see it?"
"Oh no, Sherlock. You're going to be the man who killed me, the genetically enhanced monster guilty of the murder of the man he framed for countless other crimes. It's beautiful, isn't it?"
And it is, a little bit. Even now, Sherlock can see the beauty in the plan, laid out so carefully, logically. The way the bits fall together like the pieces of a grand puzzle…
Jim is still grinning ridiculously. "In fact, that's your fate no matter if you jump or not, but one way your friends live, and the other, they die.
"I'll give you some time to think, but in the end, it's a simple question with a very obvious answer, and what do you think that is?"
o-=
Now
Sherlock pulls himself to his feet dazedly.
He's in shock, more so than ever in his life, and not surprisingly. He's just jumped from a roof and lived.
Sherlock puts his hand to his head. It comes away crimson and sticky. He starts to probe the wound numbly but he sees John then, and the doctor is staring at him in horror. Sherlock sees his knees give out and the man crumbles to the ground.
He recalls, abruptly, a conversation with Mycroft, back when he'd first met John. A warning that he'd ignored.
His father fought in the Wars, Sherlock. Fought for the humans, as if I need to tell you that, and if he finds out about your heritage the wrong way he won't take it lightly.
Suddenly, the only important thing now is John, convincing him that this isn't what it looks like. That he isn't his father, nor any of his comrades.
He staggers, balance unsettled and eyes wide, while his friend picks himself up and fights to do the same.
And John turns on his heel – in revulsion? Fear? – and starts to run.
=-o
John reels as he regains his senses. He meets Sherlock's eyes for a fraction of a second before he spins, and, unconsciously, his legs start to move as fast as they can.
John, as an army doctor, is very familiar with the fight-or-flight, or acute stress, response. He understands the chemistry of the reaction: Chemical messengers are released in order to trigger the hormone cortisol, causing other reactions required to boost energy. Adrenaline activates physical reactions preparing for intense muscular activity, including accelerated heart and lung action, the slowing of digestion, loss of hearing, and tunnel vision.
Heightened emotional state, and attention to negative stimuli, is also extremely common.
John Watson has faced predators many times in the past. During his service in Afghanistan, and during his many adventures with his flatmate. But never has the enemy been so familiar.
Sherlock Holmes is not an animal, like the Baskerville hound, nor a faceless shape, like the troops in the Middle East. He's a man, and not only that, he's Sherlock Holmes, John's best friend. He lived with the man for the last couple years of his life.
And yet, in a couple short minutes, he becomes the thing that John's father had told him to most fear. The thing that, in fact, had caused the death of both of his parents and countless more.
So John runs. It's an instinctive reaction, and not one that he plans on stopping for the moment.
Yet another of the effects of heightened stress is limited cognitive function. When John regains this briefly, he realizes the obvious: he can't possibly outrun an Augment.
o-=
Sherlock's vision is still slightly off when he starts moving, so he stumbles a little, but he begins to run nevertheless and is less than ten meters from John when the other man jumps in a cab and the vehicle screeches away from the kerb.
His breathing grows deeper, heart pumps harder, and Sherlock's legs are a blur when he accelerates.
The cab rounds a corner, a light changes to red, but Sherlock runs.
He keeps the taxi just in his sights for several blocks. At a red light far ahead, he sees John's face turn back, through a gap in the traffic. The sight spurs Sherlock on and he closes the distance, inch by inch.
The cab navigates towards lighter traffic, and speeds along, but Sherlock starts to gain, heedless of traffic. At one point he jumps over a car, moving too slow for his liking, and at several times he is forced to make use of the rooftops.
He continues to gain, though the cab speeds up, and he can see his friend's face, white and panicked, through the back window.
It takes three blocks to close the gap from six feet to five feet, but he does. It takes even longer to close it to four, and then three, but somewhere near the London city limit, Sherlock reaches the point where he could touch the cab with his fingers if he tried.
His legs move faster still, running alongside the cab, and he sees John clearly through the window. The man has scooted to the other side of the seat, and is fumbling at his jacket, but he can't pull his gun without the cabbie stopping immediately.
=-o
John glances out the back window of the taxicab. The detective is gaining, impossibly, and John urges the cabbie to drive out towards the edges of the city, where there should be less traffic, and the man obliges, spurred on by the promise of a hefty sum.
They're miles from Bart's, and John's had a head start, but Sherlock is closer still and then, at one point, he is running next to the cab, keeping pace.
Even the cabbie is startled by this, but stays silent. John reminds himself to empty his pockets for the man – if they get out of this.
They speed along. John promises the cab driver that he'll compensate for any traffic violations he makes.
John doesn't even know where he is anymore, simply shouting out directions as each intersection approaches, but somehow they circle, or were driven by fate, to this final destination:
Half a block from New Scotland Yard, Sherlock throws himself in front of the cab, and the driver is forced to slam on the brakes. Vehicular manslaughter, it appears, is not a crime he's willing to commit for any amount of currency.
o-=
Wild-eyed, John throws the entire contents of his billfold at the cabbie and flies out the door.
He lands nearly in the arms of Detective Inspector Gregory Lestrade, who seems to be in a hurry.
"John!" Lestrade exclaims, looking at the doctor in puzzlement. "We heard that there'd been an accident at Bart's. A witness said that it'd looked like Sherlock…" he trails off when he notices the man steadying himself on the hood of the cab, drenched with sweat, face bloodied. "Good God!"
John starts running again, but Lestrade stops him. "John, what's going on? What happened to Sherlock?"
John mutters something incoherent. Sherlock walks over, breathing heavily, but not as heavily as he should be, John notes.
He can almost see the other man's pulse from here, but maybe that's an illusion. Sherlock approaches, and John recoils back into Lestrade.
"I take it there wasn't an accident, then?" Lestrade asks.
"Not of the nature you're supposing, no." Sherlock, at least, is able to form an intelligible sentence.
Lestrade frowns. "But was anyone hurt?"
John moans.
Sherlock's voice drops. "Not – not physically."
The DI's eyes widen. "Should I ask?"
"Probably."
=-o
It takes ten minutes for John to calm down, but he won't look at his flatmate as they drive back to Baker Street for some privacy. Lestrade goes with them.
"Now, correct me if I'm wrong, but I believe you've got a lot of explaining to do." Lestrade directs his words towards Sherlock.
Sherlock and John sit in their usual chairs, though John fidgets endlessly and looks as if he's about to run away again. Lestrade stands awkwardly in the middle.
John mutters, "Go away." His glare shifts, for the first time, to the Inspector.
Something in the doctor's tone warns Lestrade away. "Maybe I should," he concurs, slowly.
He lets himself out quietly with a look that says he'll want an explanation later, and the tension level only increases.
Sherlock doesn't take his eyes away from the doctor. John can feel his eyes burning through him, just like the first time they'd met, but this time reading his emotions, not his identity. He keeps his hand ready, jacket open, but now that the adrenaline rush is mostly over, he doesn't know if he could shoot his flatmate, even knowing now what he knows.
o-=
Sherlock counts the seconds of silence, starting from the time the downstairs door slams, faintly. So he knows when five minutes have passed, and ten, and at fifteen in finally brings himself to speak, since John certainly isn't going to.
"Okay, I'll begin."
John starts, as if out of a daydream, when Sherlock speaks.
"My father's name was Khan Noonien Singh."
Hearing Sherlock say it out loud is not as much of a shock as John'd thought it would be. He remains silent, wondering where exactly he'd heard the name before. He tries to recall which Augment, which character in his father's stories Khan Noonien Singh had been, but he can't for the life of him remember. It's not the real issue now, however.
"He was born in a lab in the year 1959, a product of genetic engineering, initially designed to better the human race. He and his fellow Augments, as they are called today among the few who remember, were built with qualities that included enhanced strength, agility, and intelligence, as well as increased immune systems, fast healing, longer lifespans, and acute senses." His voice is clinical. "But you knew this all already, didn't you?
"I'll skip past the other traits, then. I won't go into detail about the Eugenics Wars," John is thankful for this, at least. "But they started in 1992, when my father's generation of Augments took power in many of the major countries on Earth. My father was the first. He ruled over approximately a quarter of the planet's inhabited land, centering around Asia and the Middle East."
John knows now where he'd heard the name. Khan had been the most notorious of the tyrants. There had never once been a mention, however, of the Augment having children.
But now he finds his son sitting in front of him, very much alive. Not good, in more ways than one.