Title: The Most Dangerous Game (1/3)
Rating: NC-17
Pairings: Sherlock/John
Word Count: ~26,000 in total
Warnings: Graphic violence, dark themes, sexual content
Summary: Written for a prompt on sherlockbbc_fic: I'd really like to see some secret!serial-killer!Sherlock, either because he's finally gotten bored of solving regular crimes, or he's been doing this all along and framing other people for it.

Extra Dark!Watson would be much appreciated. Maybe he's just seen so many people killed, and killed himself, that it no longer feels like much to be concerned about.

He buys the overalls second hand, pays cash. The ID is easy enough to fake, a more working class accent even more so. He's always been good at acting; it was one of the few things he enjoyed at school. He likes it because it's useful, slipping into another's skin, shedding it when it is no longer necessary. Wearing masks, acting the normal, plebeian, boring. It's all in the details.

He maps the man's patterns of behaviour, and the girlfriend's. She is normally home, alone, reading a book at eight, the time he knocks on the man's door and tells him there's been a gas leak. He lets him in. Goes back to watching TV, something dreadfully pedestrian. He goes to the kitchen, slips on powder free latex gloves, rolls up his sleeves, and takes a knife from a drawer. He slips his shoes off and pads back through to the living room. He doesn't make a sound; he is practised and careful enough to ensure that. He makes it quick, a sharp slash across the carotid, sending arterial spray across the couch, moves one step to the left, and thrusts the knife with seventy per cent of full force into his chest. The angle is awkward, purposefully amateurish. The effect will be of someone shorter and physically weaker than him. Observation suggests it will match the girlfriend tolerably well.

Helpfully she has left a cardigan in the bedroom. He soaks the sleeve in some of the blood, and then puts it in the washing machine. Rinses the knife in the sink and puts it back. Uses tape to take fingerprints from her hair straighteners – she spends nights over – and puts them on the handle. Takes off the gloves, puts them in a plastic bag in his pocket. Washes the blood from his bare forearm. Then he leaves. All the evidence will point to the girlfriend, who should arrive at nine, in time to find the body and call the police. This is certainly not a case which Lestrade will bring to him. There's no fun in chasing yourself.

Watson. John Watson. His new flatmate. There's potential there, Sherlock thinks. He's an Army doctor, used to the sight of blood and violence, accustomed to having his hands in someone else's flesh. PTSD, going by the psychosomatic limp and the nightmares. Surely he won't have any qualms about murder, not if he's pushed to it, or perhaps, convinced into it. Not if it's fun, and dangerous, and Sherlock has already seen how much he's drawn to that, how he'll come running at the mere mention of the word. He isn't normal, isn't boring. Smarter than most of the idiots he is constantly plagued with, though he doesn't always show it. There are the beginnings of something useful here. Perhaps even a partnership.

Sherlock fumbles for the packet of nicotine patches, slapping another one onto his arm with a certain satisfaction. There is this new case, the serial suicides, to occupy his mind, but he can't keep focus on it, keeps being distracted by John, this curious man. It is so unlike him, to feel anything stronger than a kind of uninterested distain for another human being. The mere fact that he does shows how singular John is. He wants to show him how engaging it can be to explore the other side of the law, the sleazy underbelly of the city, the fun that can be had in the perfect, untraceable crime. It is the best, the only, counterpoint to solving cases like this one, and what other slight diversions Lestrade can find for him. If they were all as entertaining as this, he wouldn't need to resort to crime, which after all holds more dangers, especially if Mycroft were ever to get involved. If there is one person who might be capable of bringing him within the mediocre reach of those imbeciles who call themselves the police, it is his brother. It's just... he does get so very bored.

But back to the problem of John, and how to make him realise that laws are for ordinary people. Mundane people. Not like the two of them. It will be slow, and he can't expect results at once. Patience is not his forte, but he thinks just this once he might be able to manage it. If it wasn't in pursuit of such bloody ends, he thinks Mycroft might actually be pleased.

Standing behind the police line, watching Sherlock sitting in the back of the ambulance with a bright orange shock blanket draped over his shoulders, John can't believe quite how alive he feels. In that moment, everything had narrowed down to the gun and the target, the mind calm and focused, his hands steady. Exhaling, firing... then the world snapping back into motion as he ducked out of sight behind the wall. He should probably feel guilty about killing a man, but it's nothing he hasn't done before, and there's no arguing that he deserved it. And he had probably saved Sherlock from a needlessly risky gamble.

He smiles at Sherlock when the man finally wriggles out of Lestrade's clutches and comes over, feeling lighter and happier than he has ever been since coming back to Britain. He feels like he did something worthwhile tonight, protecting this man, no matter that they've only just met, and don't exactly know each other yet. It's a feeling of triumph he hasn't felt since Afghanistan.

"You're an unusually good shot for an army doctor," Sherlock remarks once they're out of earshot of the police, and of Mycroft.

"I practised," John says, knowing he sounds a little defensive. "I take pride in my abilities. I enjoy it." Sherlock cocks an eyebrow at him. "Being able to hit a target," he adds hastily. "Not the... killing people thing."

"I never said anything about killing."

Goddamnit, John thinks. He doesn't know why he bothers. Sherlock can read him like a book.

Sherlock has been trying to drop clues as to his moonlighting activities in the weeks since their first case together, but he's not sure John has noticed anything. Perhaps he's being too subtle? After all, though he finds he is starting to have some degree of fondness for the man, he shouldn't let the unexpected sensation take away from his logical assessment of John's abilities. He is still an idiot, if not quite as bad as most, he must remember that. But it's quite simple. He has been careful to tell John that he's going out each time, and when they make the papers, to circle each article in red pen. But John just seems to think he's fishing for new cases to keep himself occupied, which is accurate in a way while still being completely and utterly wrong. Maybe he should start bringing home trophies, though it goes against every instinct he possesses. Surely the risk would be worth it? But no. He will just have to be more obvious.

After they escort Sarah home, rather shaken, but feeling a lot better, she says, now that she is safe and everything's over, they wait for a cab to come by, loitering on the pavement. Sherlock lends him his scarf against the cold night air.

"That's the second time you've killed someone while we've been on a case," Sherlock says. "Is this going to become a regular occurrence?" He sounds excited at the prospect.

"What?" John says, startled. He hadn't been thinking about it like that at the time, it was just a matter of saving Sarah's life, but now the adrenaline is out of his system and he's started to come down from the high, he has to wonder just how much he was actually aiming the thing with his kick. He can't feel unhappy with the outcome.

"You don't hesitate. Something the army trained out of you." There is an almost manic glint in Sherlock's eyes. It's quite nerve-wracking to have all that intelligence focused so intently on him. "Tell me John, do you still feel guilty about it?"

"Why don't you tell me? You're the genius." His heart rate picks up. What is he so afraid of? That Sherlock will see right through him, that he'll know about that quiet feeling of satisfaction at a job well done, that sick thrill of almost pleasure that he has tried to deny he feels. The war changed him, and he doesn't like the result.

"True, but I'd like to hear it from your own mouth. Emotions are not as easy for me to read as cold hard facts." He smiles. "Sociopath, remember?"

"I don't feel anything," John lies. It's as close to the truth as he's willing to get, and Sherlock will never believe him if he says yes, he does feel guilty. Yet somehow, he doesn't think he has fooled him at all. He just doesn't understand why Sherlock keeps pressing the point. Does he want him to admit to it? His motives are like his deductions; inscrutable.

Midnight. Sherlock has disappeared into the night leaving him to make his way back to Baker Street alone, something John is starting to become used to. No doubt he'll appear in the morning, not having slept or eaten, with the answers to their latest case. It isn't far from the crime scene back to the flat, which is lucky, as he doesn't have the cash for a taxi, if he could find one at this hour. He doesn't mind the walk. The cold air helps him think.

It isn't what you would call a nice area of London he has to walk back through, but he has his gun. He's perfectly calm about it until he overhears the sound of a struggle in the shadows of the nearest alley. There's no instant in which he makes a conscious decision, it's just instinct to run over and investigate, maybe help if need be. What he sees makes him freeze.

Two figures are locked together, a man and a woman, in what a casual observer might have thought was sex. John though has had the benefit of Sherlock's company for too long already to be fooled. The woman is struggling against the man, not writhing with him. The dim yellow streetlight catches the glint of a blade. John reaches for his gun, drawing it smoothly from the small of his back and training it on the man. He steps forward.

"Get your hands off her," he says loudly.

The man stops. His knife is already buried in the woman's ribcage. She has gone mostly limp, scrabbling at his arm weakly. In John's professional opinion, she doesn't have long to live. He moves closer, trying to get a look at the man's face.

The killer turns towards him, drawing the knife out smoothly, letting blood spurt fitfully from the gaping wound he leaves behind, and John's breath catches in his throat. He knows him. Richard Dyer.

Dyer spots the gun and backs off, holding his hands in the air, still clutching the bloody knife. John keeps his face hidden in the shadows. He doesn't want to be recognised, and he probably would be. He and Sherlock have talked to Dyer before during this case, the last time only this morning before Sherlock had his customary moment of brilliance and worked out that he was the killer in the latest set of murders. The police were looking for him at this very moment. It seems he has struck again.

"Drop the weapon," John says coldly. "Stay where you are while I call the police or I will shoot."

"Big talk from a short man." He grins, unfazed. "It probably ain't even loaded."

"I assure you it is." It would be so easy to kill him. The woman is unconscious from blood loss, little that can be done to save her now. There are no witnesses.

Dyer begins to bend down to set the blade onto the alley cobbles, but John sees how he shifts his balance in preparation to move before his hand lashes out, sending the knife flying towards him. John dodges. The metal clatters against the wall, and Dyer makes a run for it.

Breath in. Aim. Breath out. Fire. It's easy. Uncomplicated. The bullet takes Dyer in the upper back, between right shoulder-blade and spine. A good shot in the darkness, but not fatal. The man crumples though, letting out a gasp of air that's clearly audible. Probably hit a lung. Dyer is writhing and gasping on the ground like a landed fish, whimpering in pain. See how you like it for a change, John thinks. He walks over slowly, in no rush, and puts a bullet in Dyer's brain. It feels. So. Damn. Good.

It takes a while for it to sink in. This wasn't self defence. He can't argue he was protecting a life as he might have done with the cabbie. He didn't have to kill Dyer, he had disabled him, he could have called the police to come and arrest him. This was vigilante justice, what he just did. Murder for the thrill of it, just to get the adrenaline pumping through his veins again, to bring him back to the new him, the hidden self that was forged in Afghanistan and that he's been trying to push away.

Deep breaths John. It's not so bad, he thinks, trying to convince himself to stay calm. They might have his ballistics on file from the cabbie, but they never linked that back to him, and he thinks only Sherlock (or Mycroft if he was at all interested) would put two and two together and come up with John Watson. He tucks the gun back at the small of his back and heads onwards to Baker Street.

There is a sound of running water. Sherlock blinks, and the room comes back into focus. He has been overindulging on nicotine patches lately. He is quite aware of the necessary dosage required for any of the more unfortunate side effects, having used the poison a number of times when boredom dictated, but while it is excellent for his powers of deduction, it can narrow his focus a little too much. Obviously it's John, returned from his overly long walk back from the crime scene. He expects the water to stop, but it doesn't. What is John doing in there that requires so much washing?

He rises to go and find out; he has insufficient data to make a deduction from the sofa. He makes his way to the bathroom quietly, wanting to catch John unawares, before he can try to hide anything. Not that it would fool Sherlock at all, but it will save the hassle. The door is ajar, the light shining out into the dark hallway. John's breathing is audible over the sounds of water splashing; hand washing, Sherlock's mind supplies. Louder than it should be, and faster. High emotions, not physical activity. Sherlock moves closer and begins to push the door open. It swings 50° before John notices.

The reaction is quite telling. John starts violently, whirling to face him. The soap in his hands slips out as his grip tightens reflexively and disappears somewhere in the vicinity of the toilet. His eyes are wide in panic. Sherlock takes all this in in moments, analysing his appearance and all those little clues that speak so loudly to him.

"You should have gotten rid of the gunshot residue by now," he says.

John gapes at him. "What?"

"There is a fine spray of blood on your trousers, indicating a shot at close range to a man lying down. Obviously a man, you are too chivalrous to kill a woman, even a criminal one. No doubt a head shot considering your training. A rapist or murderer, to arouse such strong anger in you." Sherlock smiles. "Am I right?"

He already knows he's right. It seems, oddly, even more satisfying than usual. John killed a man tonight. That makes three since they met, and this one was what most people would quantify as cold-blooded murder, judging by John's atypical reaction. This is good. He can work with this. John is progressing nicely. The only unexpected thing is the strength of his own reaction. Satisfaction certainly, but also an odd warmth that seems to curl in his abdomen, a strange heat he is sure he has never felt before. He has no experience with the emotion – generally he tries not to feel more emotion than he can help. This... he will have to think about this.

"You... I..." John seems at a loss for words. Sherlock frowns a little. Surely he can't fear Sherlock would turn him in to the police. They may have only known each other for six weeks, but that should be long enough for even the most moronic member of humanity to realise that he only takes cases because of boredom, not out of any particular respect for the law.

"Well clearly I'm right John, there's no need to stutter so. It's obvious to anyone with the least amount of wit. Luckily, Lestrade and his band of imbeciles to not possess anything of the sort, so you have nothing to worry about."

There is a long silence.

"It was Dyer," John says finally. "He killed a woman in an alley, I overheard it..."

Sherlock nods encouragingly. "And you shot him twice, of course. Quite understandable. Come on through into the kitchen, I know a very effective method of removing bloodstains from clothing."

"I... okay." John follows him out of the bathroom. It is obvious even to Sherlock that he is not thinking clearly at this point. Possibly he is in shock. Maybe Sherlock ought to get him an orange blanket, since that seems to be the standard treatment in these situations.

"I thought you would react differently," John says once he has been relieved of his trousers. Since they don't own an orange blanket, Sherlock puts an ordinary white one around his shoulders. John looks confused. "Why do I have a blanket?" he asks.

"It's for shock."

"I'm not in shock."

"That is what I always say, but if no one listens to me, a certified genius, I'm certainly not going to listen to you."

"Certifiable more like," John mutters, but he smiles, so Sherlock knows he must have done something right.

"I would ask how you're feeling, but I think it's quite plain. You are feeling guilty about the fact that you don't feel guilty. In fact you enjoyed the experience, as you have done on all three successive occasions."

John's smile disappears. "I don't know what you're talking about."

"Don't be disingenuous John, it doesn't suit you."

"If you knew all along, why did you bother asking in the first place!"

Sherlock sighs internally at the intellectual hopelessness of the majority of the human race. "I was attempting to persuade you to admit it. I only wanted to encourage you to come to terms with the changes that you have undergone during your time in Afghanistan. It is obvious that your laughably inept therapist was not about to do so."

"What, you mean the fact that I'm no better now than any of the killers you spend your time helping Lestrade put away!" John is angry now, his eyebrows furrowed, his face flushed, his pulse and breathing rate quickened. It is a more helpful emotion than false guilt at any rate.

Sherlock raises his eyebrows. "I remind you John, I am a sociopath. With respect to the rules of behaviour laughably called morals, nor am I."

John deflates rapidly, seeming to shrink into his blanket. "Sherlock, you don't mean that," he says quietly. "You help the police, you solve crimes! Your actions say differently. Otherwise you would be doing just what Donovan keeps saying you will, and start killing people yourself every time you got bored."

It is an almost herculean struggle to stop himself from pointing out to John that he does just that. The man can be so wilfully blind sometimes. Well. He isn't ready for the truth yet. Sherlock won't tell him until he has come to terms with his own amorality.

"Go to bed John," he says instead, pushing him gently in the direction of his room. "You can continue your tiresome moral crisis in the morning."

John lets out a humourless laugh, but he goes. Sherlock watches him all the way up the stairs, thinking. This will be a good partnership. John enjoys killing, and he doesn't actually have any qualms about it. He just wishes he did. To Sherlock, the actual act of bloodshed is not what 'gets him off' as Sergeant Donovan would crudely put it, but the puzzle itself, the game. However in practical terms, this is merely an academic distinction. People die either way. Perhaps, for John, he can restrict himself to people who 'deserve' it.

He begins to deduce what these strange new feelings are. Surprising as it may be, he finds himself sexually attracted to John Watson. He has to admit this is an interesting development. It merely remains to see if John will reciprocate it.

Warehouse. You know the one. Come at once. SH

John re-reads the text, puzzled. What warehouse? He isn't aware of any particular warehouses that have some kind of significance... ah. The one where he met Mycroft, though he can't imagine why Sherlock couldn't just have come out and said that like a normal person. Ha. Normal. As if that has any bearing on his world any more.

His military training stands him in good stead in working out how to get back to the place. He hadn't exactly been concentrating very hard on it the first time round, what with being sort-of kidnapped. He makes a couple of wrong turns and has to backtrack several times. He's on foot. It's slower, but he doesn't know the address, so a cab wouldn't do him much good. He finds the right street eventually.

It's late. There is no-one around. A car he doesn't recognise is parked at the dead end of the alleyway. The door to the warehouse is open just enough for him to slip through.

Sherlock is waiting for him inside, vibrating with the kind of eagerness he only has when they're on one of those cases which he feels are actually some kind of challenge. John can't imagine why he feels that way now. There isn't anything special happening at the moment, unless Lestrade has come up with something new since the last time he saw his flatmate.

"Come on John, hurry up," Sherlock says. "We have a guest, and I would hate to keep him waiting."

There is something John doesn't quite like here. Who is this 'guest', and why do they need to meet him in such an out of the way place as this? But he follows Sherlock anyway, deeper into the maze of crates wrapped in the industrial equivalent of cling film.

"Observe!" Sherlock cries triumphantly as they round a corner, sweeping his hand in an expansive gesture. John takes in the scene in front of him. There is a man tied to a chair by hands and feet. He's gagged, but not blindfolded.

"Sherlock, what's going on?" he asks cautiously. He's sure there must be a perfectly rational explanation for this, even if it's only rational by Sherlock's standards. Whoever the man is, he doesn't recognise him.

"What can you deduce about this man?" Sherlock asks, quite casually, as if there is nothing at all strange about some stranger tied up in a warehouse in front of them.

"He's either drugged or concussed," John says, trying to get his brain into Sherlock mode. "His eyes aren't focussed on us, and he's swaying slightly."

"Obviously. What else?"

"Uh... he's a criminal? I mean, I don't think you'd leave an innocent man like this."

Sherlock sighs. "Banal but correct. Working class, left handed, spends beyond his means, treats women badly, lives in a council house, sells drugs but doesn't use them himself, almost painfully stereotypical, probably something he plays up."

There's no point in asking how Sherlock could possibly know all that, John thinks, rolling his eyes a bit. "So what, exactly is the point of this Sherlock? To prove how little I've been learning from you?"

"That isn't the primary reason John. The primary reason is also the reason that all those details are relevant. This morning Lestrade called me regarding the case of a woman who had been raped and severely beaten. This man is the prime suspect, but unaccountably there was insufficient evidence as to his guilt. I was called in on the hope that I could find more."

"That's where you've been all day?" John asks, surprised. "Why didn't you want me to come with you? I wasn't working today." He's on probation at the moment actually, working part time. He keeps being distracted by Sherlock, which leads to late nights, which leads to falling asleep in his office, which leads to Sarah not being very happy with him. At least she knows now why it keeps happening. They're still friends, even if their... thing, whatever it was, is over. It wasn't really working out anyway.

"It was dull. Your presence wouldn't have been particularly helpful."

John shakes his head. They're getting side tracked. "So why, exactly, is this man here then? Shouldn't he be in the custody of, you know, the police?"

"I didn't find any further evidence." Sherlock is moving, walking round... no, more like stalking round to where John is. He stops behind John's shoulder. Closer than is entirely comfortable, though he's not exactly eager to examine the reasons why right at this present moment. If it had been anyone else John would have reminded him that there exists this little thing called personal space, but it's Sherlock. Boundaries tend not to apply.

"I have no doubts whatsoever that this man raped and nearly killed his girlfriend. Circumstantial evidence abounds. But she is in no state to give testimony, and there is no conclusive DNA evidence. This man will walk free if nothing is done."

John may not have Sherlock's brain, but even he can see where this is going. "I may have killed Dyer..." he starts, but Sherlock cuts him off.

"John," he says softly. There is an odd lilt to the words. Almost crooning. "John we both know what you truly are inside. This man has done terrible things. Inhumane things. To kill him would be like putting down a rabid dog. I wouldn't tell anyone. No-one would have to know. It would be a good thing. The right thing. He will do this again if he is not stopped, I promise you that." His voice is quiet. Compelling. Hypnotic. John can feel his heart speed up. His eyelids flicker half shut. God, there's a part of him that wants to do it. A large part. The urge is... fuck, it's almost sexual.

"He's... the police. They'll notice if he goes missing. This might be out of the way, but he'll be found." He's trying to justify not doing this to himself. Because if he doesn't have a good excuse, he will. He will kill this man. He does deserve it. What Sherlock said is all true.

"He owes money to some less than savoury people," Sherlock says. "Blame will be placed on them. Why would you be suspected? You have no obvious motive. You didn't even know who he was until this moment."

"But they have the forensics of my Browning. Twice is suspicious enough, but three men associated with your cases?"

Sherlock smiles. He's so close now John can feel it against his ear. Sherlock's breath is warm against his hair. "I thought of that," he whispers. "I brought a different gun. Black market. I have my connections."

He reaches round and presses it into John's hand. He can tell by the weight that it's loaded. The noise he lets out is uncomfortably close to a whimper. "It's wrong," he says, but it sounds so weak even to his own ears.

"According to whom? I'm sure you killed men in Afghanistan who deserved it less."

That is... so very true. The semi-automatic is a comforting weight in his hand. Sherlock's fingers are still resting on his wrist. They are practically pressed together, Sherlock's body hot against his back. John wants this, all of this, adrenaline surging though him, sharpening everything, heightening his perceptions. Everything feels so much more. He raises the gun. Sherlock's arm rises with his. John's hand is as steady as iron, as stone. His skin feels electric, as though static is rippling through it, all the tiny infinitesimal muscles that control his hairs contracting. He breaths out. Pulls the trigger.

The man's head explodes in a shower of blood and bone fragments. He lolls in his chair, neck extended. The back of his skull is basically gone. John feels a bright stab of pleasure that makes him realise he is half hard. Sherlock is grinning into his neck.

"John," he says slowly. "John you are magnificent."

"Yeah?" John says. He is expecting his voice to shake but it doesn't. He waits to feel some sort of negative emotion, the slightest stab of guilt or doubt but there's nothing. Just this satisfaction, this pleasure. God, he's a sick bastard. Donovan was suspicious of the wrong person. "I would have thought I'm not enough of a puzzle for you."

"John, you will always fascinate me. I am a sociopath, yet you are the one person I care about in any way. Do you think I would do this for anyone else? Call anyone else a friend?"

There's a dead body not five feet in front of them, this is a deeply bizarre conversation to be having right now. But Sherlock hasn't moved from his position pressed up against him, and John realises with a start that he is not the only one turned on by this.

The hitch in his breath evidently tells Sherlock everything he needs to know. "And of course," the detective adds, "you're the first person I have ever been sexually attracted to."

John makes a little noise in the back of his throat. Sherlock takes it as an invitation. His hand leaves John's wrist and drops to the button of his jeans. He works it open one handed, slides his fingers in to brush against John's cock. He's fully hard now, and it feels... God, it feels so good. He lets his head drop back against Sherlock's shoulder, baring his neck. It feels like a submissive gesture, and Sherlock takes it as such, fastening his teeth into his flesh. The bite stings in all the right ways.

Sherlock strokes him leisurely, and John can't help but buck up into the touch. Fuck. He'd never even imagined this scenario before now, what Sherlock's hand would feel like, eager yet still unsure, unpractised. Has he ever even done this to another person before? It's such a heady thought, that this might be Sherlock's first experience of sex, even if it's a hand job in a chilly warehouse with a dead man staring at them and the scent of fresh blood in the air.
That fact really should have been more disturbing. It isn't though. Sherlock is making little noises in his ear, whimpering, rubbing his hard cock against the small of his back, frotting against him. It's desperate, jerky, and John can't decide between moving back against it, or pushing into Sherlock's hand. He would try and reach round and help Sherlock get off but the angle's all wrong. The best he can do is just hold on to his hip.

He still has the gun in his right hand. He drops it, letting it clatter loudly on the floor, and reaches up to tangle his fingers in Sherlock's curls. His hair is so soft, and he can't help tugging on it lightly. From Sherlock's moan, he likes it a lot.

John is close, so close, and Sherlock is too be the increasing speed and lack of co-ordination in the way he writhes against him. Next time, next time they're going to do this in a bed, and he's going to hold Sherlock down and fuck him, or maybe the other way around, he's not fussy, and maybe he'll run the muzzle of his gun down the long lines of Sherlock's spine, and...

"I love watching you kill," Sherlock whispers in his ear, and he comes, so hard he thinks his vision in going to white out. "Maybe next time you should watch me do it." He barely hears the words in the orgasmic haze, and the surprise he ought to be feeling barely registers.

Blood. Red. Scene tinged with it. Sky. Earth. Mountains.

Gunfire. Sharp. Knife sharp. Smell. Hot. Hot. Hot.

Breath in.

Screams. Turn. Look. Man on ground. Faceless. Moaning. Innards, outwards. Shrapnel. Bleeding. Dying.

Scalpel in hand. Sun glints off metal. So sharp. Digging into flesh. Save him? Kill him? Blood, hot over hands. Lick it off.

Lick.

Lick.

Taste copper, iron. Heavy, hot, good. Arteries, for a fast death. Veins, for slow. Slice it slowly. Oh so slowly.

So hot. Hot like hell. Dead smell. Rot smell. Corpses. Bloated.

Sun. Heat.

Blood.

John wakes up with a gasp.

The early morning sun is shining through the window onto the bed. John breaths deeply, trying to get the memory of the dream out of his head. He has dreamed of Afghanistan before, but never like that. Never. It felt so real, so perverse, so pleasurable. What exactly has he unlocked within him? What kind of monster?

The warm body next to him shifts, and buries its nose into his neck. John turns his head, and sees Sherlock, asleep for the first time he's seen since he has known him. He looks peaceful. Happy. You would never guess that last night he had jerked him off after John had killed a man, and then they had come back to the flat and fallen into bed and kissed lazily until they fell asleep. It's... surreal. He almost can't quite believe it happened.

He reaches under the pillow. The gun from last night is still there. It must be real. God, now what? What does he even think he's doing? This isn't right, none of this is right. Maybe he should just go and turn himself in to the police right now.

"Could you have your crisis of conscience a little quieter perhaps," Sherlock mumbles into his skin. "This is really quite pleasurable."

John jumps. "I didn't realise you were awake," he says cautiously. He hadn't imagined Sherlock would be this... cuddly, awake.

"You were thinking too loudly. By the way, you have work in an hour, and no doubt Lestrade will want to talk to me at some point today."

"Work." He hadn't realised. But of course, he might be a murderous vigilante killer by night, but he still has a real job, like a normal, sane, non psychopathic person. God, what is he going to do? He can't just go and sit in the GP surgery and make small talk with Sarah and think about how good it felt to blast that bastard's head open, and how Sherlock tasted when they kissed, and the little gasp he let out when he came. His concentration will be all shot to hell.

"Yes work. And stop being so melodramatic." Sherlock raises his head from John's shoulder and props himself up on his elbow. "This is no time for the equivalent of a gay freak out." He's smiling. That might have been his idea of a joke. John rolls his eyes.

"It's all very well for you to say, I bet you've never done a days work in an actual normal job in your life."

Sherlock makes a face of clear disgust. "And why would I want to? My brain would rot before the morning was out. God no."

John laughs. This is all surprisingly domestic. It's not something he ever expected from a man like Sherlock Holmes, he has to admit. He flips the covers back and rolls out of bed, stretching. If this is going to continue, and by God he hopes it does, they might need to buy a bigger bed. The sun is not yet warm on his bare skin, but the lack of clouds in the sky promises a hot day later on.

"There isn't any milk, by the way," Sherlock says, reaching a long arm down to the pile of abandoned clothes on the floor and fishing out his phone. He starts texting. Under normal circumstances, John would be more than a bit annoyed at that revelation, seeing as it was Sherlock's turn to buy more, but he is in a good mood, and he doesn't want to break it.

"I'll have toast," he replies, starting to get dressed.

"The Lurpak on the top shelf has a colony of E. Coli in it. Don't throw it out please, it's important."

John rolls his eyes, but heads towards the kitchen. Eating anything in here has required developing some finely honed senses for potentially lethal food. He leaves Sherlock in his bed. Apparently having avoided sleep for as long as humanly possible, he is taking advantage of the opportunity to laze about.

It's only later, riding the tube to work, that John remembers the words Sherlock whispered into his ear last night. He feels a chill of unease. It's going to bug him all day, he's sure of it.

John ends up working late, as patients run over their timeslots and a backlog runs up. He can blame his own distraction at least a bit for this. He can only spare half a brain for their diagnostic problems, so caught up is he in wondering what Sherlock had meant, although since spending so much time with the man, even half of his brain is better at spotting little useful clues than it used to be.

So what had Sherlock been referring to? That seeing John in action had made him want to experiment for himself with what it felt like to kill a man? Or something a bit darker? Maybe Sherlock has murdered before. Maybe Donovan was right. He banishes the thoughts from his mind. He can't afford to think of them right now. It isn't the time. That will come later.

When he finally makes it through the door at six, Sherlock is waiting for him, his armchair swivelled to face the door, his fingers steepled in a thoughtful, considering sort of way.
"You want to know the meaning of what I told you last night," he says, eyes flicking to John as he walks in.

"Yes." John says cautiously, moving to hang up his coat and dump his bag of paperwork next to the sofa. This should be... interesting.

"I hadn't meant, at the time, to mention it. I was hoping to save it for a more opportune occasion, but, I confess, the unexpected intensity of our sexual encounter made me incautious."

John tries very hard not to blush at the bald, matter of fact way Sherlock describes it. Instead he just nods for him to continue.

"I almost told you once before, when you insisted that my actions proclaimed that I wasn't essentially like you in my moral standpoint."

John is aware that Sherlock is being more than usually clinical about this, almost as if he is trying to dissociate from it. He can only assume that Sherlock is, what, afraid of John's own reaction? "So what you're telling me," he says slowly, "is that you do kill people... have been killing people."

"Correct," Sherlock says, very quietly. He won't quite meet John's eyes. "Donovan is a more perceptive woman than most give her credit for. Or perhaps, more paranoid. Certainly she has reason to be; her last boyfriend was abusive, certainly a sociopath, though less intelligent than I am and therefore less able to work out the social cues required to stay out of prison; no doubt she sees the same basic characteristics when she looks at me, it must be said I usually can't be bothered to play nice for the normals unless strictly necessary..."

"Sherlock!" John interrupts him. "Sherlock, calm down. I'm not... I'm in no position to judge you right now, okay!" That might be essentially true, but it doesn't stop John's heart from beating faster, from nausea rising at the thought that Sherlock has been going out murdering people just because he was bored. But isn't that just what John himself did last night? Killed for the pleasure of it? Because it made him feel good? And he hasn't even got the excuse of being a sociopath; he is still capable of empathy for his friends, his family, has none of the other diagnostic characteristics...

Sherlock blinks at him. "Just because you don't think you are in a moral position to do so, doesn't mean you aren't judging. Please. This is why I wanted to wait until you were a little more at ease with yourself, before getting on to me."

John sits down on the couch heavily, running his hands through his hair. "I just... I don't know. I suppose I took comfort from the fact that you were better than me."

Sherlock laughs. "John, I encouraged you to kill a man in cold blood last night, and you still clung on to some fancy about my moral superiority?"

John has to smile a bit at that. "Yes," he says. "Well."

"I was going to drop a few more hints, and then surprise you with an invitation to view my work. It would have been... nice."

It surprises a chuckle out of John. "What, like a date you mean?" he says, then stops. Thinks back over the last few sentences. "Wait? More hints? There were hints before?"

Sherlock rolls his eyes. "Yes, John. The newspapers? I though they were quite clear."

"Newspapers... you mean those red circles? Those articles, those were all you?"

Sherlock smiles. "At last you get the picture!" He seems relieved. "I still have them, if you wanted to peruse them. Of course, if you have any questions, I would be happy to explain my methods..."

John gapes at him a little. "Sherlock, are you... showing off?"

"It does grow a little disheartening when I am the only one who knows anything is suspicious. Of course, the planning it takes to make it seem like a dull, ordinary crime is the draw to my intellect in the first place, but it would be nice to have a challenge once in a while."

"How... how often do you do this?" John asks, not entirely sure he's quite ready to hear the answer.

"Only when I have to. Boredom, as you know, is intolerable to me, but I much prefer the cases Lestrade brings me."

"Does Mycroft know?"

Sherlock makes a face. "One must assume that he does; with Mycroft, anything otherwise would be very stupid. But he has never said anything to me about it. I should like that state of affairs to continue."

"Okay. Okay." John feels very tired, all of a sudden. He had suspected all of this, yes, he knew that, but he had been hoping – forlornly hoping, as it turned out – that Sherlock would prove him wrong. He ought to have known better. "So... what now?"

"We kill people John. That's something you need to come to terms with. You'll be much happier when you do." He looks so calm about it all. So very different to John's own inner turmoil.

"So you're taking over as my therapist now are you?"

Sherlock smiles at him. "I suppose I am, yes."

Well that's that then. As John goes to find a take-out menu under the clutter on the kitchen table, he realises, with a chill, that he is already looking forward to their next little... outing. He wants to see just what Sherlock is capable of.

Hypocrite, he tells himself firmly. It doesn't help.