A/N: Very nearly there, my friends. The next chapter will be the last, I'm sure. And sorry about the delay! School and work caught me up.
John… Sherlock's mouth felt dry. Of course Niles had told him to follow him up - of course he'd been goading him into doing something stupid! He cursed himself for being so predictable. John looked positively terrified, the expression on his face as he locked eyes with detective enough to send an unfamiliar wash of guilt into Sherlock's chest. He hadn't wanted John to see this. But surely John would understand if he explained? But what in the world would he say?
You've been living with a serial killer, John. Yes, that would help with the shock. He's been feeding you his victims. And that would be equally as comforting. Here I am John, so why don't you go ahead and sack your stand-in? Actually, I've already done that for you… Absolutely brilliant. Sherlock stood over the surgeon, breathing heavily. He must have looked manic. He raised his eyes to the doctor, just managed to catch a glimpse of the sandy-blonde blur as a heavy fist crashed into the side of his face. Sherlock stumbled backwards, cheek stinging, tasting blood, and resisted the urge to smile. I'm a soldier! I killed people! said the memory in his head.
There was a silence, and Sherlock almost anticipated another blow. Instead he heard the click of a cocked gun, his head shooting up as the gunfire sounded, a single round echoing into the darkening sky.
Niles lay dead on the ground, a steady flow of blood pouring from the wound in his head. Sherlock looked at John in alarm. The soldier's face was carefully guarded, his eyes honed and focused on the body in front of him. But Sherlock saw the faltering in his features, anticipated the failing of his knees and was there with a hand at his back when he dropped to the ground with an "Oh Christ" and a heavy breath.
"When did you learn?" Sherlock asked quietly and John shook his head.
"I didn't. He… he told me. Or rather… showed me."
The doctor pulled his phone out of his pocket and Sherlock tilted his head quizzically at it as he pulled up a list of long exchanges between himself and Niles, most of them texts but for the last few, which were a series of photos of such a graphic nature that Sherlock tightened the grip of his hand on the doctor's shoulder.
"When did he send these to you?" Sherlock said, taking the phone from John and flipping through the pictures. He saw hints of what must have been the room in his home at East Finchley, dismembered limbs, what looked like freshly cut slabs of meat, a picture of the fridge at Baker Street and what looked like an exquisitely prepared steak - and then a captioned picture, a microphotograph of some bacterium that looked familiar to the detective -
Rooftop. Could be dangerous. - Niles
"Clostridium botulinum," said Sherlock quietly before tucking the phone away in John's pocket. The doctor raised an eyebrow, finally breaking his stare away from the body in front of him.
"I don't know… half an hour - what?"
"Let's get off the roof. We can phone Lestrade for the body," said Sherlock, heaving at his friend. John budged slowly, and the detective found himself half exasperated and half endeared by his clumsy movements. The man had been through quite a revelation in the past few hours. Whoever Niles had been working with was watching, Sherlock knew, so instead of moving quickly he wrapped his arms around the doctor and clasped him close to his chest. The less suspicious they looked, the better - he was almost certain the photos the surgeon sent would get the lot of them into trouble. "Act natural," the detective whispered, and he felt the doctor's body go rigid against his.
"What are you doing?" whispered John, seeming to have forgotten how to speak and breathe at the same time. Sherlock extended the doctor to an arm's length.
"Embracing you, John. Isn't that what friends do when one's been away for a time?" he said, matter-of-factly, as if there weren't a dead bleeding body at their feet and incriminating photographs on their mobile phones. And a possible gunman watching us from afar, Sherlock thought, his eyes fighting the urge to dart about the cityscape past the doctor.
"Well, yeah, but you don't hug people, Sherlock. It's - um. Weird."
"You're not people, John. Now come, downstairs."
The detective grabbed him by the wrist and led him at a leisurely stroll to the fire escape and below, but John paused at the lip of the roof and looked back at the body of the young surgeon.
"Don't… don't call Lestrade," he said, and Sherlock cocked his head at him. How very like John to become sentimental over a killer - the man's addiction to finding the good nature in people was borderline childish.
"The proof is on that phone, John. There's plenty of evidence to incriminate."
"Yeah, I know. That's why I don't want him called," said the doctor. "He… do you know how many people would be upset by this? At Bart's? How many patients loved him? It would break them. They can't know. No one can."
Sherlock looked at him, saw the definitiveness in his features and decided John had a point. It was the genius of his ability to connect, or pretend at it that made people so heavily dependent on him. He saw the effect on his patients, and he saw the effect on John.
"Then how do you propose we deal with it?" the detective asked, and John gave him a queer look that mildly perturbed the detective, partly because he had never seen it on John's face before, and partly because it bore shades of an expression the dead doctor on their roof once wore.
"I'll take care of it," said John.