A/N: This is my first fic in the Sherlock fandom and I'm so excited to be joining such a talented group of people. The title, which you may have recognized, is take from the Elton John song, Your Song. I hope you enjoy and please feel free to leave reviews!

This is Your Song

In the year they've been living together John has come to enjoy the sound of Sherlock's violin. He'd never been one for classical music, but as the months went by it became a comfort, Sherlock was safe and reasonably content and John could relax. And John became more and more knowledgeable than he'd ever thought he'd need, or want, to be about classic composers.

: : :

Nine months ago John had never heard of Dancla or Mazas. 13 months ago John had thought his life was over, the rest of his days passing grey and boring in a bedsit. Nothing happens to me.

He asked Sherlock once, feeling oddly at peace with the fact that his flatmate was playing violin at three in the morning and trying to connect a little with him over something that was not a dead body, if he was playing Bach, one of the only composers John knew anything about. Sherlock had actually stopped playing, put the violin down, and spent the next 45 minutes listing all of the reasons that Bach was overrated and how the real artist of the time period had been an Italian composer named Francesco Maria Veracini. After that John learned to ask who Sherlock was playing instead – it lead to fewer rants.

Sherlock, it turned out, even owned some CDs of violin music. He didn't listen to them often – John had only seen them emerge after three months of living in the flat. Sherlock always preferred to play rather than listen but sometimes, after a long case when his body had been pushed past it's limits hours, if not days, ago, his fingers couldn't manage the delicate strings. Instead he'd put a disc in, throw himself onto the couch, and finally give in to his body's demands. Sherlock was always asleep before the CD ended.

John found the CDs comforting. It was a way of knowing that, for the moment at least, Sherlock was asleep in the flat, safe with John. He never asked himself why that thought made him so happy. Rather he'd watch Sherlock sleep from his chair in their sitting room, letting to the music wash over him.

It was nothing like hearing Sherlock play of course, but still, it was nice. More than a few times he'd woken to dim morning light and a complaining shoulder, the music long over.

: : :

As the months go by John begins to associate different composers with Sherlock's moods. It's not surprising really. Any sort of verbal communication beyond insulting someone or proving his own intellect, or often enough both at once, proves nearly impossible for Sherlock even when he wants to say something. That uh – thing tha – that you, uh, you offered to do that was – good. And John doesn't like to wonder how it is to live with a brain that never stops thinking, always tracking six or seven things at once. The violin allows Sherlock to deal with his emotions in his own way and it keeps their furniture (and their walls) intact. Really, it's as close to a perfect solution as John could ask.

: : :

Veracini is, of course, a favorite.

Sherlock seems to prefer it for thinking, using the music to help his brain catalog all of the data he needs for this case or that experiment. There are days when they are on cases that he doesn't utter a word, playing the violin until John is forced to take it away and gently try to rub some feeling back into those tired fingers.

John notices Sherlock's fingers carving out chord progressions against his leg at a crime scene one night. He doubts that Sherlock, who is busy insulting Anderson and traumatising a witness, even realizes he's doing it. John revels in the warmth of knowing one small thing about Sherlock that the man himself does not. It will most likely never happen again after all.

: : :

Dancla is for when he's bored and restless.

Other composers float in and out of the flat too – Kroll and Rode and even Hubay once in a while – but Dancla expresses Sherlock's boredom in a way nothing else can. When days go by without any word from the Yard and everything John can offer Sherlock as distractions are deemed "boring" and "useless" and "stupid" and "pedestrian" and John just keeps offering up ideas out of desperation to keep Sherlock occupied, he plays Dancla.

Lestrade sends them cold cases when he can but Sherlock won't even bother with half of them. The other half he solves within hours, calling Lestrade up to ask if he even went to the academy or did they just give him that shiny badge for looking pretty, badgering the DI until John takes the phone away and apologizes, quietly thanking him for keeping Sherlock busy for a few hours.

John keeps his gun locked, in a bow, in a drawer, in his room now. It won't keep Sherlock out, not if he really needs or wants to get in, but it does tell him that John wants to gun left alone and usually Sherlock obliges him. John likes to tell himself that it's out of respect for him as a friend but he half wagers that Sherlock just doesn't want to hear the lecture he got last time – from him or Mrs. Hudson.

With nothing to shoot he plays constantly. Just because the rest of his brain is going to rot from boredom, he once tells John, doesn't mean his knowledge of the violin should too. John suggests, somewhat playfully, that he try to learn something useful, perhaps the solar system for instance, but really he is simply grateful that the violin seems to help and takes to leaving tea and plates of food next to its case where he knows Sherlock will find them.

: : :

Mazas is for much darker moods.

John read once, before he was even enlisted, still just an over eager medical student, that almost all people who have a genius level IQ are depressed. It makes sense, so much brain power and so little stimulation. And, so, it makes sense that when it's Sherlock, with a brain constantly moving so fast that nothing can hold his interest for long, when he sees more in five minutes than most people see in a week, that the depression is even worse.

In some ways it's almost worse living with Sherlock on a case. John has to tempt him inch by unwilling inch into eating, sleeping, and changing his clothes. More than once he's tempted to dump Sherlock in the shower, fully dressed, just to see the look on his face. Instead he reminds himself not to be cruel – the only way Sherlock knows to drag himself out of his moods after all is with cocaine which is not happening if John has any say whatsoever – and makes cup after cup of tea that goes untouched. There are entire days when Sherlock will do nothing but lie on the couch in his pajamas and stare at the ceiling, moving only to play his violin.

The jagged notes of Sherlock's mind imposing themselves on the violin's strings brings the same pang to John's chest as the heavy, oppressive, silences do. He would almost prefer the silence except that the music let's him know exactly where Sherlock is, how bad things are, and if he has any hope of convincing his flatmate to eat or at least get off the sofa.

Some days he opens the door from the street and hears that pain, crying out the only way Sherlock knows how, and John has to remind himself that he was an army doctor. He was in a war. John has had men and women and children die under his hands in the blinding desert sun because he was not fast enough, or good enough, or prepared enough. John has seen hell and lived to tell the tale. Somehow though, that all pales in comparison to the idea of going up to the flat and finding Sherlock trapped in his own head, full of pain and misery, completely unable to break free.

He threatens, once, to hold the violin hostage until Sherlock eats dinner and almost drops it when he sees the look Sherlock is giving him. John has stared down insurgents who looked less intimidating. Instead, because he has a healthy sense of self-preservation whatever his therapists may have said, John carefully sets the violin back down in its case. Sherlock eats two bites of John's sandwich and then plays for six hours straight.

John counts it as a win but never tries anything like it again.

: : :

One day John comes up to the flat loaded down with Tesco bags, and Sherlock is playing something new. John pauses in the doorway watching Sherlock who is playing with his back to him, looking out onto Baker Street. He listens hard for a minute and then ventures a shaky "Is that Corelli?" Even though he's sure that's not right.

Sherlock turns without pausing in the music to look at John. "No." He says after a moment.

"What is it then?" John racks his brain trying to remember the last time he had to ask Sherlock the name of what he was playing but it's been months. Sherlock's repertoire is as familiar to John's ears as his own name by this point and hearing this new song makes him feel off balanced in the most wonderful way. The song, whatever it is, makes John think of warm summer trips to the country and the satisfaction he feels after preforming a difficult surgery successfully. It's careful and sure and quietly pleased all at once and somehow it makes sense to John and he desperately wants to know the name, the composer, anything that will let him hear it again.

Sherlock eyes him strangely and gives John a one shouldered shrug, never pausing in his playing, "Just something that's been stuck in my head," He says blandly. "Nothing, really." And just like that he turns back to the window leaving John clutching the shopping.

: : :

The next time Sherlock leaves the flat, yelling about the morgue at St. Bart's and an experiment to see if caterpillars will eat recently deceased human flesh – John has long made peace with the fact that sometimes he just does not want to know – John goes through Sherlock's music collection.

It doesn't take long. Sherlock has seven discs of violin music, but John only needs to listen to a little bit of each to realize that none of them are right. He checks the other CDs on the shelf, opening all of them in case Sherlock has for some reason hidden the one he's looking for, but it's not there either. John gives up on finding the song that way but resolves to ask Sherlock about the surprising amount of David Bowie he has in his collection.

: : :

When John comes home from the surgery the next day, dinner already in hand, he hears the familiar notes of one of Dancla's later pieces slip into the mysterious, new, song Sherlock had been playing before. John fishes his mobile out of his pocket and sets it to record before going up to the flat.

Sherlock, standing by the fireplace, twitches the corner of his mouth up in the shadow of a grin when John enters and continues to play. John sets his phone on the table, hoping against hope that Sherlock will not pay any attention to it, and unpacks dinner. After one look at the kitchen table – something is growing in a bowl that John had brought with him when he moved in and he's fairly sure there's a human thumb in the salt shaker – he brings plates and take out boxes alike into the sitting room.

As he listens to the last few bars of whatever Sherlock is playing he realizes something. It's not the same.

It's similar. Extremely similar actually. But this is – more relaxed, in a way. It reminds John of dinners at Angelo's with Sherlock. He remembers nights spent laughing into his plate as Sherlock made extremely personal, if accurate, remarks about the other diners and resigned, rueful, smiles when Angelo brings them a candle – more romantic that way he always tells them with a wink that makes John blush and Sherlock raise an eyebrow, amused.

John can't pick out the differences exactly – he knows next to nothing about music except for his Sherlock-taught violin knowledge – but they're there. Small ones he probably wouldn't have even noticed if he wasn't so desperate to know what it is exactly that Sherlock is playing. Sherlock however stops playing nearly as soon as John notices the differences, putting the violin safely in its case and coming to eat dinner. John saves the recording and pockets his phone quickly, resisting the urge to so much as look at his flatmate. Somehow, and God only knows how he'd do it but he would, Sherlock would know he was hiding something and John would have to explain how he's managed to become obsessed with a song he's heard all of two times. So he slips the phone into a trouser pocket as casually as he can and tosses a fork at Sherlock.

They spend the rest of the evening in front of the telly – Sherlock loves to watch action movies and point out all of the impossibilities as well as which actors were sleeping with one another during filming. John doesn't mind, there will always be a certain novelty to watching that brilliant mind at work, and it's honestly rather amusing. It also allows him to think about the song he can't seem to get out of his head.

: : :

John spends the next week playing the recording to anyone that may know what it is. He asks school teachers, and violin teachers, and anyone who plays music professionally or has ever been in or near an orchestra, and he even plays it over the phone for his uncle who has more classical music than anyone John has ever met. They all have the same response.

Beautiful, but I've never heard it before. Sorry.

He plays the recording to himself, at lunch or when he's taking the underground home, and is grateful Clara bought such a nice phone, one that plays music. It quickly becomes the soundtrack to his days, humming it as he visits patients or carefully scans groceries at the chip and pin machine.

: : :

A week after that they have a row. Nothing major just two very different people getting on each others nerves, and John decides to take a walk down to the pub and back. He isn't gone long, an hour at the outside, and even as he shuts the door with a little more force than necessary they both know he'll be back. It's April, their window is open, and Veracini follows John down the darkened street.

When John arrives back at 221 there is still violin music floating out their window – still Veracini but he thinks it's one of his earlier pieces now. He steps up to the door, key in hand, and freezes. The music has changed. John is positive Sherlock was playing Veracini a moment ago but this – he steps inside quickly pulling his mobile out. John listens hard for a second and then hits the play button on his phone.

Yes, it's definitely the same song. But, like last time, it sounds different now. Even now, with the two versions playing nearly on top of each other, John can't tell what exactly it is that's different. The notes don't seem any different but the sound. It's sorrowful, he realizes. The music sounds sorrowful now, and it reminds John of telling a platoon one of their men hadn't survived when they already knew the news was coming. It's resigned, and painful, and he sees the eyes of young men who have seen too much death and are too tired to realize it.

John hurries upstairs pushing the memories away. It's beautiful and haunting and he could listen to it for eternity if only he didn't know exactly what it said about Sherlock's emotional state.

He walks the last flight of steps, people running up their stairs almost always means trouble after all, and enters the flat with a cautious "Hello." Sherlock is already facing the door and the look he gives John is very definitely, for him, wary. John notices two fresh looking cups of tea of the table and sees that the jar of eyeballs which had started the fight – he just didn't want them in his bed for Christ's sake! – has vanished. John knows a peace offering when he sees one. "Fancy getting a bit of dinner?" For any normal person it's far past time for dinner but for Sherlock, and now John, it's a perfectly reasonable question.

The song changes again, just slightly, but now it reminds him of that surge of relief that comes when a bullet just misses you, when a bomb goes off just before your squad is within range. He thinks of waking up in the hospital when he'd been sure he was never going to wake up again.

"I do not currently require food." Sherlock keeps playing. "But, I suppose I could accompany you, if you'd like."

"Oh?" John raises his eyebrows. "When was the last time you had a proper meal? And nicotine patches do not count as food, Sherlock."

Sherlock averts his eyes, answer enough, and puts the violin away. "Perhaps some pasta." He murmurs putting his coat on. John claps him on the back with a smile, the fight may has well be forgotten as far as he's concerned. They head out and he tries not to grin as he watches Sherlock catalog everything about the situation, clearly a bit off balance. John has a feeling that Sherlock won't be deleting this particular evening from his database.

: : :

John's had a theory about the song for a few weeks now.

He doesn't like to think about it much though. The implications, both if he's wrong or he's right, are terrifying and he has no idea how to deal with them. That doesn't seem to matter to his brain though. The song is stuck in his head constantly and John tries to focus on that rather than what his mind thinks the song means.

Sherlock still plays other songs of course. They had three days of Mazas the other week and John was grateful the mystery song hadn't made an appearance. He shudders to think what it would have brought to mind.

Thankfully the Mazas is short lived when a case comes in courtesy of Lestrade. John listens to four straight hours of Veracini before Sherlock revisits the crime scene demanding to know if the victim owned a pair of old, blue heels. She did and John spends three days looking up shoe companies from 60 years ago and trying to sleep whenever Sherlock isn't playing the violin or tearing around London like a mad man. Finally, on the fourth day of the case, John finds the name of the shoemaker. Sherlock drags him to the Yard and then two abandoned shoe factories yelling abuse at Anderson the whole time. An hour later after a very complicated explanation involving courting traditions, the second World War, and a certain type of flower that was once used to produce blue dye but had the side effect of killing dye makers, they're in a cab on their way back to Baker Street.

John is musing over a title for the case – The Cinderella Shoe perhaps – when Sherlock falls asleep on him.

It's not completely unexpected, his flatmate hasn't slept in nearly a week, but John is going to hate waking Sherlock up to get him into the flat. The weight of the other man is comforting though, solid and steady against John's side. He cautiously lets his arm wrap around the other man, keeping him close, and tells himself it's strictly out of friendship. Sherlock's only response is to turn his head into the curve of John's neck and mutter something about factory conditions during wars.

The cabbie drops him a wink when he pays – John can't exactly blame him now can he and these days he's finding that he doesn't mind the implications quite so much – and then watches with obvious amusement as John wakes Sherlock up. There's a careful balance between waking Sherlock up enough to get him into the flat, and waking him up completely ensuring he won't go back to sleep for hours if not days.

"C'mon, you great lump." John says fondly, shaking Sherlock a little. "We're at the flat, Sherlock. Get up, unless you feel like paying to sleep in a cab all night." John swears he hears a muttered pedestrian from his flatmate. "Yes, yes, out of the cab now. You're too big to carry, you have to walk a bit, Sherlock."

With a great deal of prodding John finally finds himself unlocking to door to 221. Sherlock is still mostly asleep and balks at the stair case. John takes Sherlock's hand, it's like leading a sleepy child, and urges him up to the flat. John has carried wounded, dying, men over his shoulders through desert heat with no problem. Getting Sherlock to walk upstairs like an adult should not be this hard.

As soon as they got through the door of 221b Sherlock throws himself onto the couch and is blissfully asleep in seconds. John had hoped to get him into an actual bed but at least he's sleeping. He throws a blanket over his friend and drags himself upstairs to his own bed.

Nine hours later when John wakes up, Sherlock is still asleep on the sofa. He makes tea, pouring two cups without thinking about it, and sets the second one on the table pushing aside a book about bees. Bees? Why do we have a book about bees? John drinks his own tea and then takes a long shower letting the hot water wash away the grime of London's abandoned factories. He's just started moving his shoulder gingerly, trying to work out the knots, when he hears violin music, muffled by the noise of the shower's spray.

It's the song again, he can hear it well enough to know that, and when he shuts the shower off 15 minutes later Sherlock is still playing. John dries off, dresses, and makes his way into the sitting room. He's humming along under his breath letting the song wash over him. It's warm, that's the thing that comes to mind at first, the song makes him feel warm. And, he realizes a minute later, the song makes him feel warm because the song reminds him of home.

It's a patently stupid observation, Sherlock would be terribly disappointed if John said it out loud. He's in his home after all, Sherlock only ever plays the song at home, how could the song not remind him of home?

But it's different. There are so many tiny versions, so many different things that this song, the song, his brain finally let's him admit it, that Sherlock has written for him, tries to say and this one is meant to say home. John closes his eyes and let the song bring him memories of warm nights spent on the couch watching telly as Sherlock hunches over his computer; of eating take out at three in the morning after a case; falling asleep in a tangle of limbs on the floor after hours of running over London; all the times that John has found human remains around the flat and told Sherlock off for not disposing of them properly. This is home for John, and it has been for so long now that he's amazed he didn't admit it to himself before.

No sooner has John reached the sitting room than does he have Sherlock's full attention. Sherlock, still in yesterday's clothes, plays a few more bars, watching him with eyes that will see more than John can ever hope to understand, and then stops, holding the violin at his side in a gesture that almost looks nervous. "Have you finally decided to acknowledge it?" Sherlock asks, never looking away from John's face. "There was that recording, God knows you've been listening to it on your phone often enough, John. You must have it perfectly memorized by this point." Of course Sherlock had noticed John's phone recording him playing all those months ago. He'd just decided to keep his observations to himself for once. Marvelous.

"And" Sherlock continues in a voice that he usually uses to explain to everyone else exactly how idiotic they all are, "You've had the idea about its origin for ages now, nearly two months, it started just before that case with the shoes – The Cinderella Shoe, really, John? – but I thought it might be best to let you work it all out on your own, let you take your time with the idea rather than trying to bring it to your attention directly."

John blinks, and then starts with what he feels is the most ridiculous part of all of this, "Is it possible to come up with a title you actually like, or are you planning on rejecting them all on principal?"

"They don't need titles!" Sherlock protests, rolling his eyes. "And really, John, you feel that was the most inane bit of what I just said?" John shrugs good naturedly and Sherlock rolls his eyes again. "You're going to be horribly obvious about all of this, aren't you?"

"Probably." John agrees walking up to Sherlock and taking the violin. He carefully puts it in the case, followed by the bow, and then closes it all with care. "You wrote the song for me." He says, standing just a bit too close to Sherlock for politeness. It's not as if Sherlock has ever respected anyone's personal space though.

"Obviously." Sherlock tries for disdain, pedestrian, but John knows better by now. John can see the tiny licks of worry in the other man's grey eyes.

"A love song," John clarifies and yes, maybe he is enjoying this a bit more than he should, but that won't change the fact that he's going to draw it out as long as possible. How often does one get the chance to force Sherlock Holmes to explain himself, to have power, any sort of power, over the other man? Possibly he is a slightly bad man for this. But he doubts Sherlock is all that upset by that particular prospect.

"Is there a point to all of this?" Sherlock demands. He tries to step away but John snags him by the waist and the shocked look on his face is priceless.

"I just want to make sure I'm clear. I'd hate to move forward without sufficient data." John says in a passable imitation of Sherlock.

"I compose a love song for you that, according to everyone you've asked, is quite lovely. What more evidence could you ask for?" He shouldn't be surprised, of course Sherlock found out he was asking after the piece, but he is, just a little, and it makes him smile fondly up at the other man.

"Just one." He assures Sherlock and the calculating look on Sherlock's face makes him want to chuckle. John tilts his head, the implication clear, and waits.

"Ah." The corner of Sherlock's mouth lifts up in a smirk. "It is important to collect as much relevant data as possible." He agrees. "It appears that living with me for so long has actually managed to improve your skills as a scientist. I'm glad to know I'm having such a positive influence on you, John. Maybe your blog will be more accurate now. Lose the titles perhaps?"

"Shut up you enormous git." John scolds, ensuring Sherlock listens to him by sealing his mouth off with a kiss. John has been waiting for this for months and for all of his 'not really my area' business on that first day, Sherlock certainly seems to know what he's doing. He makes a mental note to ask about it later.

"I believe," Sherlock begins when they finally pull apart, and John, his head resting on Sherlock's collarbone, doesn't need to be able to see his face to know that he's grinning like the cat who got the cream, "That we could gather better data in my room. Without our clothes."

"I'm afraid I am just not that kind of girl, Mr. Holmes." John protests with a smirk of his own, his hand slowly snaking it's way down to Sherlock's groin. And he laughs, feeling impossibly young and happy, when Sherlock drags him through the flat by his hand, at least one experiment sent flying in their haste.

John, as he is pulled onto the bed, knows exactly what his song will remind him of from now on.