AN /: This story was pretty much just in the form of the line in the summary for a few months before I got around to writing something to go with it. It won't go for that long, three chapters max. AU, obviously.

Disclaimer: 'Sherlock' and all characters within belong to the BBC, Steven Moffat and Mark Gatiss. Batman and The Riddler belong to their respective owners as well, I'm just taking them for a joyride and I make no profit from this.

O.o.O.o.O

When You Need A Hero

Ch 1. What To Do With A Gift

John first realises that he is capable of something very strange when he is seven years old and has the misfortune of falling out of a tree. He lands on grass but scrapes himself along a few rocks that have picked the most inconvenient place to lie, and when he inspects the damage he finds a mess of red lines, blood, and broken skin down the length of his arm.

Annoyed that his playtime has been cut short he hurries home and asks his mother for a bandage, but his mother gives him a bemused look and tells him that he doesn't need one. Indignant, he sticks out his arm to show her, and then realises that although his arm is dotted with lines of dried blood, there is not a single scar on his arm.

For a while after that he forgets all about his strangely quick recovery, but when he is twelve years old it happens again. This time he falls off a bike and skids down the asphalt road, aching all over when he rolls to a stop. He lies for a few minutes to catch his breath and then rolls over onto his side to check the damage, and is amazed to find that the broken skin on his hands and legs is closing up and repairing right before his eyes.

When he gets home he doesn't tell anyone about this, not his mother and especially not Harry, because he has seen enough cartoons and read enough comics to know when to keep a secret. He is also practical enough to know when the universe is giving him hints, and six years later he is studying to be a doctor.

O.o.O.o.O

When John is a year into his studies something else happens to enforce the fact that he can do something very special.

One evening as he is walking through the city looking for a place to eat because he had skipped lunch and his stomach is growling at him. It is late, the weather is hot and muggy, and a street away from him the driver of a large car loses control of his vehicle and ploughs into a truck on the opposite side of the road, the truck in turn flipping two smaller cars that crash onto the footpath. John hears the bang and sees the accident at the other end of the street and dashes up to help, his legs burning as he sprints.

He is not the only one who has arrived to help and begins to work with a tan, middle-aged man with strikingly blue eyes to help the driver of one of the overturned cars on the footpath. The driver is a young woman, miraculously unarmed but heavily bruised and bleeding from a large cut down her leg. Working silently with the man they pull the woman from her car, and as John takes a hold of her legs he feels an odd tingle starts in his chest and works its way down his fingers. Out of the corner of his eye he notices that the wound on her leg is healing, the flesh is closing up and blood is no longer pouring onto the cement. This fact registers as very strange somewhere in the back of his mind, but is pushed down for him to worry about later that night as the sounds of an ambulance ring in the distance.

Once the woman is loaded up onto the ambulance John breathes a sigh of relief, laughing nervously as the tension starts to ease form his body. The other man gives him an odd look and turns to face him, and for a moment John thinks that he is about to be yelled at

"You know,' the middle aged man says to him instead,' you were pretty calm back there. I don't think I've ever seen anyone so young so calm when there's so much blood around."

"You see a lot of blood?" John asks.

"I serve in the army,' says the man,' they'd do well to have someone as professional as you."

John makes a noncommittal noise and stares at the mangled remains of the car, not entirely sure what to think.

O.o.O.o.O

As it turns out John enlists in the army after a few years of very emotionally charged work in GP's and hospitals, and his decision to do so may or may not have had anything to do with a tan, middle aged man dying in some god forsaken desert because an incompetent medical officer could not reach him before he bled out over the sand.

O.o.O.o.O

The next few years of John's life are not what he expects, and this is probably for two reasons. The first is because he quickly gains a reputation for being a very reliable and competent doctor thanks, to very special powers which no-one else knew about. The battlefield is a remarkably good and unusual training course for his ability to heal by touch, and the more he practises the more lives he saves. Eventually his power is tuned and practised enough that he can heal all major internal wounds without looking suspicious, where the wounded is brought back to base, examined, and told that they are extremely lucky not to have died already. His squad quickly gains a reputation for being lucky, and most of the men he works with tease him about having it as easy as, well, as easy as carting a wounded soldier back to safety under heavy fire can be. John smiles and jokes back with them, because they don't know how wrong they are.

The second reason is because for a year he takes a break from the army to strike out on his own, travelling around for a bit and seeing some sights.

America had been... one of the most interesting places in his travels, to say the least. It is there that he first comes to grips with just how much good he can do with his ability to heal, specifically when he is walking past a bank just as it explodes. Smoke fills the air as glass rains down on the streets, and when he looks up people are crawling out of the wreckage on hands and knees. His army training comes in useful here, keeping him calm as he moves towards the smoking building to see if he can help.

He is only a few footsteps away when a figure appears, clad in a ridiculous and rather tight green body suit, his face masked by a single purple band of cloth across his eyes, leading a troop of henchmen through where the heavy wooden doors of the bank used to be. Even army training hadn't prepared him for this. Not a minute later a man dressed head to toe in black and sporting a mask with two small, upturned points on the sides of his head that also covers his face dashes through the building. There are sounds of a struggle inside and John tries to get a closer look but the fight is over almost as soon as it begins. What he does see is the man in black walking out, brushing rubble and dust from the bat-shaped motif on the front of his skin-tight suit, his mouth pulled into a grim line. There is also a long gash down his forearm that he hasn't seemed to have noticed, and John walks forward to ask if he needs any help.

The man in the black suit gives him a look of surprise and declines, moving to walk away, but John grabs his arm before he can leave, a familiar tingling working its way through his fingers as the broken skin pulls itself back together.

"Um... thankyou?" the man says, examining his arm, and although John can't see the man's eyebrows he just knows that they are raised in surprise. Or maybe curiosity.

"Just doing my job,' John says,' can't even get a break on holiday."

The man seems to appreciate the joke, his mouth curving into a small smile. "I could use a friend like you,' he says,' that power of yours could come in very handy."

John doesn't have time to say goodbye as the man withdraws a steel bat-shaped grappling hook, pointing it at the top on an adjacent building and swinging himself into the air and off out of sight.

It is as John is walking back to the dodgy motel that he is staying at that he puts the clues together, and then he stops in the middle of the street, much to everyone else's annoyance and loud complaints. Eventually he just chalks it up to the fact that he was on a bit of an adrenalin rush and still a bit jetlagged, because who in their right doesn't recognise Batman while they're wandering around in Gotham City?

O.o.O.o.O

For the rest of the time that he spends in America John just happens to be around when Batman is around, like someone has attached a homing beacon to his back, or maybe even a weirdness magnet. He manages to be present at banks that are being robbed, walks past buildings that explode in fiery showers of concrete, steel and glass, and finds himself somewhere in the blast radius of each and every nuclear reactor near the city. His healing powers start becoming more and more useful due to these circumstances, and by the time he arrives back in England it is like he hasn't been on holiday at all, especially not when he re-enlists and is dropped back into the thick of things. He goes straight back to routine, and it is like he never left.

End Chapter One