Sherlock!AU: John Watson was assigned to spy on Sherlock Holmes, under the order of James Moriarty. He got too attached to Sherlock and when Moriarty realized this, he used it to his advantage. What Jim didn’t know was that John went to the other side and chose Sherlock, instead of being his ‘pet’.
I figure someone’s probably already grabbed this idea and is running with it, but I can’t help myself so I’ll just throw up some of the headcanon this gifset gave me if you don’t mind:
In the interests of keeping John in-character, rather than starting out as Moriarty’s operative, he ended up working for Moriarty because he owed him. John Watson always pays his debts, no matter how unwanted; in Afghanistan he and some of his unit were trapped for several weeks in a sticky situation and he didn’t have the medical supplies to treat all of the wounds leftover from their being ambushed; for “a price”, he was offered supplies from a shady source, “M”, that he had no choice but to accept. Coming back home months later, “M” gets in touch to redeem the debt. John seems like the most loyal, harmless, genuine man in the world, and the perfect man to spy on Sherlock Holmes, who, for all that he’s a deductive genius and a cold bastard, is still ludicrously sentimental and accepts completely to the fiction of the honest soldier and never once questions John’s actions. He is following me around inexplicably? Oh, he is starved for action, for purpose, and I can give that to him! He just committed murder to save me? Oh, what a marvel is the heart of a good man! I simply must keep him, my new, human wonder.
John starts out disliking Sherlock immensely, both because Sherlock is the crazy bugger who’s apparently gotten “M” fixated and is making John’s life hell, and because Sherlock is openly scornful of simple things like the importance of human life, the very thing for which John all but sold his soul. So, at the beginning, John is quite free with his dispensing of information, and impresses “M” by using the most open and innocent method possible of doing so, a simple blog. None of John’s activities are suspicious, and Sherlock is already set to believe only the best of his wonderful little soldier, wanting and expecting John’s company always, even saving him when John does not want saving, when John gives himself up so that he can just get offed by the Black Lotus and not have to live this life anymore.
And with time, though Sherlock still gets on his nerves, John can’t help but regret everything not for his own sake, but for Sherlock’s; the man’s never had a friend in the world before this, and John’s sorry that Sherlock’s trust is so misplaced; that the only person who’s his friend just for the sake of being such is, of course, not; that Sherlock’s going to die, as per “M“‘s master plan, and that it’s going to be John’s fault; that Sherlock will end up both beaten and broken. So the blog and the information John’s supposed to supply, on pain of death, “slips his mind”. “M” confronts him about it, in his roundabout way.
When John’s only barely apologetic, things start exploding, as is their wont.
And then people start dying, an intended prelude to Sherlock’s gory, sad demise, the scene that’s already been scripted and blocked out: John is revealed, Sherlock’s heart breaks and burns, and the poor idiotic genius dies twice, once when John walks away with the adversary, and then again with the explosion of the bomb they’ve left behind.
But damn that John Watson, because it doesn’t work out that way.
Jim Moriarty knew John was a fool, knew from the start that the man’s morals would get in the way of his willingly carrying out the task for longer than the required three months. But he also knew that men like John Watson don’t take well to men like Sherlock Holmes, and so while he would never enjoy his duties (more’s the pity), he would not miss Sherlock when it was over. So though John, as soon as Sherlock starts shaking his head wildly (looping denial like something broken) at his bitten confession, obviously wishes that he were not a catalyst for the poor man’s destruction, he would never wish to go with him. Jim has planned this out from the start.
Evidently, John’s more a fool than Jim even realised, because the good loyal soldier is good and loyal to the last and remains on Sherlock’s side, no matter the cost — even his own life.
A wrench in the wheel; hence, improvisation, as any player must do when his fellows forget their lines: John must die. Luckily (unfortunately) for everyone, their great idiot genius, far from either running when told or leaving John behind in disgust for betraying him, saves him. Yes, the bomb goes off, but no, the defector doesn’t die; the mark simply won’t allow it, and fate allows him the delusion that he can change the world, lets him have his victory, for a while.
Afterward, Sherlock won’t allow anything but the belief that John is his friend and is here to stay, and won’t even accept John’s apologies and offers to leave for both their safeties, adamant that John has nothing to atone for. John was indebted, he insists, and they’d have never met otherwise. (Or so Sherlock believes; John is not so sure, and it eats at him, great and raw and ravenous.) Mycroft says Sherlock is a fool, Sherlock warns Mycroft not to lay a finger upon the defector. John can’t believe Sherlock still trusts him. Sherlock says John’s just feeling guilty, but does make John promise to inform Sherlock of any further communications from Moriarty. But John was told that as soon as a peep to Sherlock was made, it was both of their lives, and he is in no doubt that it’s still true. It’s ultimate betrayal both to keep silent, and to let Sherlock die. Sherlock knows this. Sherlock still trusts John with his life.
And so, there they are, fifteen months later; word finally gets out to the press: John Watson was a plant! He’s been spying on the tabloid’s sweetheart sleuth all along! That’s one mystery the detective couldn’t crack! The evidence, the kidnapping: Moriarty knew all of Sherlock’s movements, from somewhere close by. It appears conclusive. Kitty Reilly insists she knows the truth, there’s months of evidence that John has been sending updates constantly, that the pool affair was an elaborate set-up, completely staged, an attempt to bind Sherlock to John completely after seeing the operative defect so movingly. Sherlock doesn’t want to, no, won’t, doesn’t, believe it: Reilly’s source is some nobody called Richard Brook, a heavy on the very lowest rungs of Moriarty’s organization. That’s nothing, Sherlock insists, against John: his best friend in the world, acquired under unfortunate circumstances but all the stronger and better for it.
John doesn’t defend himself. Then, he disappears.
(What Sherlock doesn’t know: when he was enthralled with his microscope, Molly Hooper offered whatever help she could provide to John, who sat counting down the hours before the world turned full-circle upon him. So when John vanished into the night, he went to her, and gave her a memory stick that she was to give to Sherlock, when the time seemed right. He said he wasn’t allowed to do anything more direct to fix the future. She almost cried, and she hugged him, and his face was ghostly, already.)
Imagine then, if you will, how Sherlock’s heart cracks anew when John, after hours of nothing, is on a roof, that roof where they first met, where fate and chance and misfortune brought two unlucky sods together and set them spinning to their destruction, together; imagine, then, how pathetic Sherlock sounds as he insists that he knows John, that he’s a genius, unfoolable, infallible, that John has never lied to him about anything that matters, that he could see the change in John after the pool, after John was freed of his burden, after everything spun on its head. John tells him he’s a bloody idiot, that he ought to have learned by now that caring was hardly an advantage. Sherlock, sweating sentiment against the mobile’s plastic, still believes only the very best of his wonderful little soldier.
“No-one could be that good, Sherlock.” He sounds irredeemably sad.
“You could,” Sherlock says, and he might be crying.
Everything comes at a price. John always pays his debts.