Being half vampire was something that had virtually no effect on John Watson's life. He knew that because he had seen how his father lived. Scott Watson had become a vampire shortly after Harry's birth. Julia Watson, from that moment on, had been considered a widow by the world at large. John's father couldn't set foot in daylight and had to kill, or at least maim, human beings to survive. John had a father but everyone assumed that he didn't. He couldn't speak of Scott Watson and when Scott Watson had finally killed himself sixteen year old John could speak to no one save his family about his grief. Not that he would have spoken of it to any so called friends anyway.

It had been interesting but sad having a father he could only see in the evenings or at night – sometimes during the day if the rest of them got the shutters and cracks bolted securely enough. Storms and grey days were a delight for the four of them. John knew that they meant the world to his father – the light in his eyes and the eager smile had been obvious to all. John just wished that those days, and the nights with them, had been enough to stop him climbing up on the roof and not coming down before daybreak.

Life had been a misery in many ways to Scott Watson. John Watson's life was easy by comparison. It had started out problematic. As a baby he'd had to be given blood from his mother as much as milk - the blood of animals every couple of days had worked well enough. When he'd hit puberty, however, he'd almost tried to kill one of Harry's girlfriends. She'd been ushered quickly out of the house and then Harry and his mother had manhandled him down to the basement for the real vampire of the house to deal with.

Sun had never been a problem. He healed at a slightly faster pace but nothing too attention grabbing. Everything had pretty much gone in his favour until father had informed son that he'd need to take human lives to live. John had rejected this idea and, through sheer willpower and refusing to kill anything but birds and rodents, had managed to suppress the need for human blood to a sporadic thing. And there were other ways of getting human blood; he was going to be a doctor after all.

"You can't fight it forever, son," his father had warned him.

His first kill had taken place when he'd moved away to uni. The rats weren't doing it for him, nor was his own wrist, and he was out of his mind with the blood lust that his father had never let him see. There had been a big party at one of the halls and it had proven ample hunting ground. No one worried about his strange, desperately lethargic behaviour; they either assumed he was pissed or were quite pissed themselves.

His name was Luke, or at least that was what he'd told John. Luke had been drunk and looking for a snog and maybe a mutual wank in the courtyard but what he'd gotten instead was John's fangs in his throat drinking his fill until Luke had slipped away quietly, moaning John's name. Words could not explain how miserable and furious John had been. Words also could not describe how fucking brilliant he'd felt either.

Luke was listed as missing twenty four hours later. Nothing was ever found of him. John knew how to clean up his mess.

He doesn't want to think of how many people he kills before he's working at Bart's and can be surrounded in blood all day and all night if he so chooses. He hasn't killed a human for food since. That includes Afghanistan. He doesn't count easing a friend's, or enemy's, passing from devastating injuries as murder.

John wakes up with the need for blood screaming in his head like a demanding toddler. He can handle this one, though. This is the kind that is usually satisfied by animal blood. The catch is that he lives in London with Sherlock Holmes and he doesn't think that hunting in the park is going to go well – and he knows that he can't wait until cover of darkness to slip off somewhere and do the deed. Really, he's shocked that Sherlock hasn't noticed something. The rest of the human race he totally understands, he forgets himself sometimes since his mother is long gone and Harry never brings it up on the rare occasions he speaks to her. Sherlock notices everything about everyone one so John finds it strange, a blessing but a strange one, that he hasn't noticed this.

That being said Sherlock is the most rational and logical human being alive. Vampires, not even half vampires, exist in his world. They just can't.

He gets dressed and stops by the mirror to get a look at himself. He looks human and not half crazed. Not yet anyway. He smiles. No fangs either. Perfect. He knows what to do now.

"We're out of milk," Sherlock informs him when he gets downstairs. "Also I require fresh grapes and an apricot." John knows better than to ask if Sherlock is actually thinking of taking in some fruit and vegetables for once in his life. There's a murderer on the loose, again, and this one's a grocer.

"Feel like steak for dinner?" he asks as he fixes some toast and tea for breakfast for the pair of them. Sherlock won't eat it while he's around but he will once he walks out the door. It's a game they play and it's one that he almost enjoys.

Sherlock doesn't look up from his mobile. "It's half ten," Sherlock informs him. "A bit early for dinner to be on the mind, isn't it? Even for you?"

John ignores the jibe to the last case, the one where John almost fainted from hunger. "I'm going out anyway," he reminds him. "I'm not going out again and we're not eating out again – rent's due soon."

Sherlock waves his hand dismissively so John takes that as an affirmative and heads out. Before walking into Tesco's he makes a quick stop to a local butcher's and orders a particularly bloody cut of meat along with the steaks for dinner. He inhales the former purchase in a back alley and feels like a new man when he steps back out into the sun. He tackles the food shopping and the chip and pin machine with ease and thinks the day can't get better. It does when he finds that Sherlock has not only eaten the toast but he's also put his tea cup and plate in the sink along with all the other dishware scattered across the flat. Just as that is hitting him his mobile beeps asking him to head back to the crime scene since he's done the errands. He also asks him to bring the grapes and apricot, please and thanks.

John's smiling so wide he pokes his canines with his tongue just to make sure his fangs aren't peaking out.

If the call for animal blood is a demanding toddler then the call for human blood is the soft, seductive voice of a lover. It's whispering in his ear before he comes to consciousness and he groans very loudly when he hears it. It's frustration but also want. At that thought he bounds out of bed and into the bathroom to check his teeth. A very slight point to them but nothing attention grabbing.

Bollocks.

He goes about his routine and gets his things together for work. Oh Christ, work...how much blood would he see today? Hopefully none. It was flu season after all. He could ignore the necks. He could ignore the exposed throats. He could do it.

He goes back to bathroom and splashes cold water on his face. "No." He orders himself. "You're not getting any of that, not anymore." Somewhere he hears his father's voice telling him he's being ridiculous. He silences it. He'll get some blood from the hospital on his lunch. Or on the way out, he just had to last until then.

Sherlock isn't there when he's gets downstairs. He isn't sure if he's sad because he's not here or sad because a convenient food source has left the premises. He is so horrified at the thought that he takes a bite out of his own wrist – not a good idea when his fangs aren't really showing yet – and sips enough to give him a jolt that three cups of dark coffee would normally do. He knew that the gesture would only distract him, would only buy him some time, but that was all he needed.

It also made him not want to slaughter everyone on the tube a few minutes later.

He doesn't know how he doesn't take down the medical student that takes the tube with him but gets off two stops before him. Her name is Nancy and she's a nice enough girl and, though he usually doesn't go for anyone that young, he's confident that he could have turned on the charm enough to get her alone and drink her dry. Something had to come with age he reckons. It's also a good thing that Nancy had been alive because he knows for certain that his fangs are starting to show. Nancy doesn't say anything but she keeps looking. He makes an effort to not open his mouth too much when he speaks and he pulls his scarf up to cover his mouth once he exits.

Sherlock, oddly enough, hasn't texted, rang, emailed or popped in all day. He smiles despite himself to find Sherlock passed out on the couch snoring softly with another apricot and his mobile on his chest. He thinks about grabbing the apricot, that's what he's thinking except instead he finds himself dropping carefully to his knees and leaning over Sherlock's oh so deliciously exposed neck.

Things would have gone really bad for Sherlock if he hadn't snored particularly loud at that key moment when John was poised to strike. He leapt back to the other side of the room in what seemed to be a single bound. He shoves his scarf into his mouth and slams his fingers over top. For some freak reason this does not wake Sherlock – not surprising, really. When Sherlock crashes he crashes epically.

He slowly removes his hands and the scarf, once he's got himself under control and after nineteen repeats of "Sherlock is my friend, not my dinner," and takes yet another feeding from his wrist. The effect goes down from three strong coffees to one and a half.

John goes back out and finds a rabbit hopping through the local park. No one's looking at him so he grabs and runs. Five minutes later he feels a bit better. The monster inside has been tricked for the time being. It won't work again.

He'll get it sorted tomorrow.

John wakes up in a cold sweat, and bolt upright in bed to boot. He is bloody salivating. That's one reaction from a nightmare that hasn't happened yet. It's the arterial spray, he remembers as he wipes the drool away from his lips. He stops, parts his lips, and runs his fingers over his teeth. Fangs are still there but they are moving from slightly obvious to very bloody obvious. As he's trying to get his breath back, and cursing himself for letting things get this far, a wrist appears in his line of sight. He considers it worthy of another medal that he does rip that wrist off the arm possessing it. Instead he turns his head sharply to his right and there is Sherlock Holmes sitting on the edge of his bed patiently waiting and saying nothing.

He knows without needing to look at Sherlock that Sherlock knows all about it, or as much as he can understand. So he simply refuses the wrist. "I'm fine."

"You have been sleepwalking back and forth between my room and yours all night," Sherlock informs him. Sherlock doesn't say that he's woken up with John standing over him but John knows that he must have. The only reason Sherlock would think to offer him a wrist would be because something like had happened. Something where Sherlock would have seen his fangs.

"Explain something to me," Sherlock says. "You function just fine under sunlight and you've never killed anyone for blood – "

"Half vampire," John explains. "Not a very strong half vampire at that."

"Of course," Sherlock breathes. "Your father I presume? The one who you said to me had killed himself when you were sixteen where official records say he died several months before your birth?"

He nods. "I'll explain it all to you later after a good night's sleep."

"Wrong," Sherlock tells him as he shoves his wrist in John's face again. "You will explain it all to me once you've fed. I assume that you don't need to feed from a human very often – annually usually? Yes? That explains a few finer details – but you need it now."

"I've got it." John shoves his arm away, with more force this time.

"You've far from 'got it,' John."

John's ready to snap out a reply but he stops himself. No, he's far from fine. He's far from fine but he refuses to chance killing Sherlock. John knows that his mother often offered herself to his father in the effort to save a stranger's life – and simply to give her lover relief. Scott Watson had had a shocking amount of self control. John, in his experience, is too intoxicated when drinking from a human being to pull back.

There was no way he was going to risk Sherlock that way. That he would risk himself that way.

Sherlock is studying him then something in his eyes softens. It's barely there but John knows that it means. He knows that Sherlock is going to say "I trust you" before he says it. It still terrifies him.

"Not good enough."

"It would solve everything."

John shakes his head. "I am not going to kill you, Sherlock."

"I know you won't. I said trusted you, remember?"

Sherlock's phone chirps. "Lestrade," he informs him. He grabs John and pulls him out of bed. "We have to move. Now." He starts to move his wrist again so John pushes him away and instead bites into his own. Almost no effect this time. Sherlock's staring at the open wound and John makes a show of applying two quick licks, one for each puncture wound, and they watch together as the marks slowly vanish.

"Better?" Sherlock asks. John knows he knows what that answer is.

He growls at him instead and stomps down the stairs to locate his coat. Maybe the running would make him forget about it for another night.

"Don't lose him!" Sherlock shouts as they rush after Jeremy Astor, the grocer-murderer. Lestrade is after the accomplice and it's up to them to nab this monster. John won't lose him. He's fully convinced that Sherlock will have him first until Sherlock actually catches up to him. The two men grapple at each other, fists and legs flying in a murderous dance until John sees a fist smash against Sherlock's head and then that head slam into the brick wall. Sherlock doesn't get back up.

It's probably not even a concussion. Sherlock will probably wake up in a few moments extremely angry but otherwise fine. It's happened before after all. It doesn't matter in that moment. Something in him, something primal and animalistic, snaps. He rushes after Jeremy with something that certainly is a snarl and leaps on him. He tries to get a go at Jeremy's neck but Jeremy seems to be very adept at keeping his teeth and hands away from him. During this wrestling match Jeremy gets hold of his gun. John tries to back away and manages to grab his own gun but Jeremy fires first.

The shot gets him in the chest. The blunt force, and the shock, alone should have killed him but he's still alive. Alive and alert enough to fire off his gun and get Jeremy in the head. Done and done. He checks over himself – he's not bleeding. Not good. Not good at all. He needs blood. He needed blood days ago and he really, really needs it now.

Then he realises what a bad idea that was to fire a kill shot like that. Blood drawn from a dead person is useless to him. Drinking blood from the hospital works because it was drawn from someone who was alive. It was always a bit cold and stale tasting but it was fine. Jeremy was useless to him as food source now – and without that he would soon die from this wound unless Lestrade somehow knew to turn up with paramedics. Unlikely.

Even though he knows it's useless he crawls toward the corpse. He drags himself, whimpering and desperate, to the man and sinks his teeth into the man's neck. He pulls away, spitting the blood out. Rotten. Useless. He's done for.

He rolls himself onto his back and waits for it all to end. Drinking from the dead is a bit not good has another drawback: it is as good as drinking cyanide. In his growing desperation he had actually managed to forget that important point.

He is about to let his eyes fall shut and then Sherlock' there. So is his wrist. "Come on," he urges, an edge of desperation there for the first time in their lives. "Drink."

John weakly shakes his head. He can't speak but he stands by what he said earlier. He will not kill Sherlock. Not even to save his own life. Sherlock is having none of this, naturally, and hauls John up onto his lap and presses his wrist right up to his lips. When John still doesn't react, and John doesn't quite know if it's weakness more than refusal here, Sherlock hauls him up into his arms this time. John's head is cradled right up against Sherlock's neck.

"Come on," he urges. "You are not leaving me. Not like this."

John isn't sure whether it's the naked terror in Sherlock's voice, the scared frustration that he is doing what he can but that it still might not work, that makes him finally take the offering or whether his ability to refuse has overcome his weakness. Sherlock gives a very slight gasp and pulls John closer to him, a hand burrowing into his hair and pressing him tight to his neck, and then thing go fuzzy for John.

Don't die, he thinks toward Sherlock as if he can hear him. Don't die. Please don't.

Things remain fuzzy for a good long while. He feels himself being lifted, being moved, and then being settled into something soft and warm. He feeds a few more times, small sips each time, and then the fuzziness becomes full darkness. He floats in beautiful nonexistence for what seems like an eternity but can't be more than a day or so before he opens his eyes. Sherlock is there sitting cross legged beside him on the massive bad that he'd bought for him in return for accidently setting his old one on fire. His eyebrow rises in inquiry.

John nods as he slowly shimmies himself up to a sitting position. "You alright?" he asks.

Sherlock turns and displays his neck and then his left wrist. Not a mark or anything remaining. "Your self preservation is amazing, John," he near whispers.

"I've been hiding it my whole life, Sherlock," he reminds him. "I'd like to think it's good enough."

Sherlock nods and regards John for a moment. "Will you live forever?" Sherlock asks.

It's a sudden question but John can't blame Sherlock for asking. "No. I'm sure I'll live a bit longer than most – you saw it takes a lot to bring me down. But no, I'm not going to live forever." And thank God for that he thinks to himself but Sherlock doesn't need to hear that.

Sherlock nods in easy acceptance. "Good," he replies. "Now, you're good for another year until you need to supplement with animal blood, yes?"

"I would assume – "

"I can get you blood easier than you can," Sherlock tells him. "On both fronts."

John is read y to object to one point of this pledge but one look from Sherlock silences him. "You don't need to kill, you've known that for years. You have me here now and t makes sense to use me."

John doesn't even get to even think his objection before Sherlock has moved up to him so he has one hand on either side of his head and is leaning right over him. "I want to do this for you, John. " There are so many other things that he's telling him between and around those eight words and John knows he can't refuse him. He's suspected that he's the first person that Sherlock has cared for in a very long time, if ever, and he can respect that since he's felt that way about Sherlock almost since the moment they met.

Sherlock smiles the smile of man who knows he's won. He leans down further until their foreheads touch and lets out a sigh of relief. It is not awkward. John even reaches up to give him a bit of a hug. When Sherlock pulls away he holds his hands out, pulling John up and out of bed and down the stairs into their life again. Then Sherlock makes them lunch.

It's a very well done garden salad.