John first starts helping out at the free clinic by accident when he and Sherlock track down one of the homeless who had been a witness to a crime. While the detective is busy grilling the man for details, a teenage boy comes in with a deep gash on his arm, blood dripping everywhere while he waits for the sole volunteer doctor who is utterly swamped with patients.
Unable to stand by and just watch, he ends up stitching the teenager's wound. Someone else approaches him with a rash, runny nose and red eyes. He diagnoses an allergic reaction, checks to see if the volunteer doctor has any antihistamines in his stash – he does – and prescribes them.
He's dragged away by Sherlock soon after, but a week later when there are no cases and his flat mate is driving him up the wall, he takes his med kit and goes back to the clinic, where he spends several chaotic hours tending to dozens of the homeless with a wide range of ailments that he's woefully undersupplied for.
Still, he resolutely doesn't reach for the gun tucked under the desk, and instead asks with his most pleasant Doctor voice perfected during those months in Afghanistan, "What seems to be the problem?"
"Tore out my stitches," the man rumbles, awkwardly shrugging off his coat and slinging it over the back of a chair. The action reveals a hip holster and gun, but the stranger seems entirely unconcerned, turning his back to John and starting to work on his button-down shirt.
John eyes the bloody stain on the cloth, then the popped stitches of the long jagged wound across the man's back as it's revealed. "Have a seat, mate, and I'll get on fixing that."
He carefully stays on his patient's right side – the holster is on the left – as he picks out the threads, cleanses the injury and sews it back together again. There's no anesthetic to offer; he used up his last dose an hour ago during an impromptu surgery when he had to pick out shards of bone from a woman's broken leg. However, the stranger goes through the whole process silently with barely a flinch.
It's when the man is putting his shirt and coat back on that John can't contain his curiosity any longer. "Sorry for saying this, but you look like you can afford going to a hospital or private clinic."
He doesn't need Sherlock's methods to see that the clothes the man is dressed in are obviously of good quality, and the gun is a recent military model that must have cost a fortune in the black market. The numerous scars on his upper body are telling, and John's gut instinct makes him disinclined to believe that his occupation falls on the right side of the law.
"I was in the area when I busted my stitches, and my usual doctor is an hour across town," the man explains simply. "I've heard good things about you."
If he were Sherlock, he would have guessed hired gun or freelance mercenary, but since he's not, he leaves aside the conjecture and politely sees his patient out.
Gifts appear on the doorstep of 221B overnight; knitted gloves, jars of homemade jam, colourful sketches drawn in children's fumbling lines. He keeps a few of the items and distributes the rest to whoever needs them. The sketches he puts up on the fridge until Sherlock starts using the paper in his experiments, then he shifts them upstairs to his room where they're less likely to suffer his flat mate's peculiarities.
Some members of Sherlock's Homeless Network begin reporting to him when he makes his trip through the shadier parts of London to the clinic. The detective doesn't much care about how information is conveyed to him as long as it is, and does an artful impression of cluelessness when John questions him about the fifty-pound notes that have started appearing mysteriously in his med kit. Shaking his head, he uses the extra to purchase medical supplies.
He and Sherlock begin hearing rumours about a new player in the London criminal underworld, someone who's still not spoken of as frequently or with as much fear as Moriarty, but enough to cause concern. They can't even get a proper name for this shadowy new figure, and can only keep a close ear and eye out for more news.
Then there are the armed individuals who keep turning up in the clinic.
They're not the ramshackle bunch which make up the majority of gang members he's treated, nor the attractive men and women Mycroft employs and sends on errands regarding John in an attempt at manipulation. They're definitely part of the same group, and show up with injuries that cannot be explained away by the common scuffle on the street.
The blond man – Sebastian Moran, ex-Colonel in the Army as he finally introduced himself as one day – wanders in occasionally for seemingly no reason other than to hang about.
"Downtime between jobs," is the only clarification he receives.
"I imagine you must have a lot of free time between killing people for a living," he replies mildly. He has his own sneaking suspicion about the employer of all these people, but ever since the Pool incident, Moriarty has been strangely inactive. John's world does not revolve around the consulting criminal, and so life goes on.
Moran huffs a laugh. "You know how it is, it was the same in the Army. Not so much with the killing recently, though."
John thinks about arguing that he was in the Medical Corps, and 'killing for a living' is not exactly the description he would use for a soldier, but in the end he directs Moran to bandage a wound, utilising the blond as a nurse.
"Put him down on the bed!" He's on his feet, mind cataloguing the shattered mess of red and white that is the man's hand, and what looks like third-degree burns on his legs. "Jesus, Moran, I don't have the equipment or supplies for something like this –"
Jim Moriarty walks in through the door, and John's words stutter in his throat, ice spiking down his spine and through his veins.
For long, breathless moments, his senses are filled with the stench of chlorine and distorted light reflecting off a watery surface.
He blinks once, twice, clearing the vision away. John Watson does not panic.
"I don't have the resources for this." Even to his own ears, his voice is eerily calm and toneless.
Moriarty smiles, something beyond frigid rage in his liquid dark eyes. "Don't worry about that, darling. My boys are bringing in everything you need."
Medical equipment are brought in by silent men and women, some of whom he's acquainted with. Beyond the door, the waiting room has emptied of all the homeless who usually throng it.
"Doc," Moran murmurs. The injured man is barely breathing.
Wondering how long it'll take for Sherlock to show up, he goes to his patient and, like he always has, tries to save a life.
"Oh, very well done, Johnny boy."
He very deliberately does not drive his elbow back into the consulting criminal's face, instead accepting a bottle of water that Moran offers and chugging it down.
The terrifying fury that Moriarty had been nursing at whatever had happened several hours ago has simmered down to a kind of cold annoyance.
"Do I even want to know what's going on? I'm sure you can afford a whole team of doctors for your men rather than having to resort to me."
Moriarty looks up from his phone, stretching his neck left and right. "Oh, I do have three doctors under my employment. Or rather, I did."
"Did you have them murdered?" John has passed beyond a point of exhaustion that makes him reckless.
A flicker of dark amusement chases over his features. "No, someone else did. Which is a problem, don't you think?"
He hates to say it, but it really is. One consulting criminal in the world is more than enough.
Moriarty looks pleased at whatever he reads in John's expression, finally shifting into the more familiar brand of gleeful madness he had witnessed at the Pool. "Now, it's incredibly rude of me, but we really need to be going. There's a pest that I simply must step on."
A flurry of activity has his sedated patient loaded onto a stretcher and carried out, bloodied materials binned and taken out. All the medical equipment is left behind.
"Wait, wait, his prescription –" Snatching up a notepad, he scrawls down a list of medication and dosages, recommended physical therapy routines and other necessary follow-up treatments.
He rips out the page and shoves it towards the Irish man, earning him an unblinking stare in an odd way that makes uncomfortable heat flush through him.
"I'm a doctor," he says defensively.
Moriarty finally takes the paper and tucks it into a coat pocket. "I'm beginning to think you're far, far more than that, my dear. Say hello to Sherlock for me, won't you?"
He's sprawled out in his chair, half-asleep. He feels like hell, his body coming down from the single-minded focused state that trauma surgeries always send him into, not to mention the adrenaline from the sudden encounter with Moriarty.
Light fingers brush against his neck, another hand wrapping around his wrist. He twitches awake, squinting blearily at Sherlock crouched in front of him.
"Blood. Intensive surgery." The detective rubs his fingers together, eyes flicking rapidly over him. His other hand continues taking John's pulse. "Are you…"
"I'm perfectly fine, Sherlock. Or I will be after a good night's sleep." He grins fondly at his best friend. High-functioning sociopath, indeed. "Where was he holding you?"
"The lab in Bart's. Molly was quite distressed."
"I imagine so. Sherlock, what the bloody hell is happening?"
Something is brewing in London.
Sherlock rambles on, his voice transmitted to John and the Detective Inspector, doing his usual in offending everyone even all the way back in London.
When the commotion in 221B starts up, John swears he catches a glimpse of someone familiar before the screen blacks out. Stabbing worriedly at the keyboard, he's only listening absently when the police officer approaches him.
"It's for you."
He holds out his hand for a phone without looking.
"Uh, no, sir. The helicopter." The distant whirring whine finally registers.
He doesn't know what he's expecting, but it's definitely not Moran piloting the copter and raising a hand to him in greeting. Checking his phone for any hint as to what he's supposed to do - no texts, no calls – he sighs and gets in.
They land south of the River Thames and guards usher him into a room in an office building, where the first thing he sees is Sherlock and Moriarty having a rapid-fire conversation. His friend is still dressed in the bed sheet, looking utterly ridiculous next to the Irish man in his elegant Westwood suit, not that either seem to care at all.
"…irritating, isn't it?""
"Um, sorry, but what's irritating?" He interrupts them.
It's Moriarty who answers him. "Someone else trying to barge in on our chess game."
"The bloke who murdered your doctors?"
"Murdered my doctors, made friends with terrorists, threatened someone here and there, the list goes on and on and on." Moriarty rocks on his heels, humming. "And now he's made his move to sweep everyone off the board at the same time."
All of this seems like a dream, two archrivals in the same room together yet focused on someone else. He glances around at the various computers set up in the room, some of them depicting files and photos, others surveillance feeds. "If either of you feel like explaining yourselves any time soon…"
Sherlock exhales a gusty sigh, the lament of a genius whom almost no one can keep up with. "Where's Mycroft?"
"Where. Is. Mycroft?" The detective whirls around to point at a screen showing CCTV footage of the outside of the clinic where John volunteers at. "It took you a few weeks to link your patients together with Moriarty and it took me five days, so I guarantee that my brother made the connection in less than three. Yet he's done nothing over the past months."
Sherlock clicks to another image, a frozen shot of Moriarty entering the clinic. "A fortnight ago, the surgery you performed. Moriarty was present in an obvious location for several hours, but there was no attempt to take Moriarty in for questioning or trace him through his network. Why? At first I thought he was dead, but no, we saw him last week."
"He lost a lot of weight." John recalls.
"Stress will do that to someone, even someone as powerful as the Ice Man." Moriarty types a long line of incomprehensible code. "Honestly, Sherlock, I'm disappointed you didn't see this coming."
His friend waves a hand ambiguously through the air to symbolise his omniscient brother. "He's just supposed to be there, playing puppets behind the scenes. He's Mycroft."
This, John realises, is Sherlock's blind spot. "What's happened to him?"
"Blackmail," the consulting criminal sings out in a lilting voice. "It's hard to work when everyone he's surrounded with has a knife to their throat. He's all tied up, working himself into knots to get around this pest of ours. Mycroft Holmes has nothing to be blackmailed over except for one. Glaring. Weakness."
"Sherlock." John concludes.
"Very good, Doctor."
The detective stalks back and forth restlessly, face twisted as he reconciles his deep-seated resentment towards his brother with the worry he's now apparently experiencing over him. A thought suddenly occurs to him as he addresses Moriarty with a smug expression. "I'm your weakness too."
Moriarty rolls his eyes. "Why else would I send someone to save you when the pest decided that today would be a good day to kidnap you and gain total control over the British Government and London underworld? You're a bit further down on his list of priorities, so don't get your head too blown up over this, darling."
Sherlock scowls. "Why is John here, then?"
"Would you have preferred I leave him to die?" the consulting criminal enquires. "Because he would have by now. There was a bomb attached to the car he drove out in."
The shock of that makes him a little weak-kneed, and he has to sit. "Ta very much for that." He doesn't know if he means to be sarcastic towards Sherlock or genuinely grateful towards Moriarty.
The consulting criminal smiles brightly at him, and John can't quite help himself when he returns it. For some reason, today his fight-or-flight instinct hasn't been triggered. Maybe repeated exposure is what does the trick. He can't decide if this is a good or bad thing.
Sherlock goes very, very still as he looks between him and Moriarty. "That's not it. John is my weakness, but you just said I'm lower down in his priorities, that his target today was you and my brother. John is hardly a weakness to Mycroft."
Too many surprises in one day, he thinks blankly. He can't muster up much emotion at the implications that Jim Moriarty, criminal mastermind, considers him as far more important than a mere pawn in his game with Sherlock.
"Jealous, Sherlock?" the words fall out of his mouth without much thought, and remarkably enough he doesn't want to take them back.
The shuttered expression on Moriarty's face breaks as he darts him a startled look. Sherlock is a mixture of resignation, annoyance and indifference.
"He's still my blogger, I need him on cases," seems to be the detective's final word on the situation, if there even is a situation. "Now, do you have a location on this irritating rat? John is a very competent shot."