I neither own nor profit from any of these characters; they are the property of Sir Arthur Conan Doyle, Steven Moffat, Mark Gatiss and the BBC.

If you see something that you think ought to be changed or improved, please feel free to let me know, if you'd like. Constructive criticism is always welcome.

Written for a one-word prompt ("cut") from Feej.

Special thanks to her, LeDragonQuiMangeDuPoisson and ImpishTubist for having read this over for me - whew, it takes a village...

Sherlock plays the violin on a night when the light leaks in through the windows, the shining notes spilling from the strings to mingle with the gleaming pools on the floor, so that everything is bright around him and his dark silhouette is contrast and counterpoint and swept away on incandescence.

It's the quiet shuffle behind him, sandpapery stroke of sound against the music, that brings him back again.

Lestrade is standing in the doorway, silver on silver in the moonlight, his hair sticking up from the back of his head in bright slivers as he keeps closely to the tiny patch of reflected window on the floor. It's as though touching the nighttime coat of shadows that wrap Sherlock might disturb some delicate balance, break the spell the detective has used to weave them together for himself.

He looks up at Sherlock and his eyes are dark, darker than all the shadows in the room where they converge upon the taller man.

Their gazes lock, moonlight on mahogany, and Sherlock breaks it first.

"What I'm playing," says Sherlock some time later. "It's sad."

Lestrade is sitting on his living room couch, eyes closed as Sherlock plays, but at the words, he lets himself breathe again, speak again, voice rough with emotion and disuse.

"I know."

"Why do you come to hear it?"

Silence, for a moment, and it's heavy, like this matters more than it seems to, more than worn pyjama bottoms and patterned dressing gowns should bear witness to.

"Because sometimes, Sherlock," Lestrade sighs, and his voice is textured grey, "sometimes it hurts less to hurt more together."

Sherlock doesn't bother understanding people and knows it, and Lestrade knows it, too, so there is no shame in asking his next question. Normally, he wouldn't ask at all, because it won't solve him a case and it won't find him a killer and it won't even bring Lestrade the hint of a tired smile, though it may go halfway and just make him tired. But tonight it seems important to ask, and he can always delete the information later.

"Why," he asks, decided, "does hurting make it better?"

It surprises Sherlock to see that he has guessed wrong. That rarely happens, and certainly never with Lestrade, who is many things, but, above all, ordinary, which should mean predictable. He has guessed wrong, though, about the look on Lestrade's face; not tired, no, but curious, and perhaps the surprise is mutual.

"There are different kinds of pain, Sherlock," Lestrade says, and Sherlock thinks for a moment that he knows the answer, because he knows a hundred kinds of pain from a hundred different crime scenes, but Lestrade hasn't finished yet. "And choosing to hurt… choosing it can be enough, sometimes, to own the pain and make it less."

Sherlock almost points out how illogical that is, before he wonders if it really is. Choice implies control, and control has real and measurable psychological benefits. If the decision to be made is between pain forced upon him or pain self-administered, he knows which he would take.

In fact, he already has. Sherlock understands something of self-destructive behaviour.

He pulls up his sleeve, eyes locked on Lestrade. On the pale canvas of his inner arm, the remembered fingerprints of his addiction trace a line from biceps to flexors, tiny, permanent notes on his anatomy to mark each muscle fibre with the sacrifices it has made for the sake of Sherlock's mind. Is he right? he asks silently. Is this a picture to go hand in hand with Lestrade's words?

He is expecting affirmation, warm on the gentle lines of the older man's face, because he knows he isn't wrong about this. Surprise jolts him for the second time that night (he wonders if Lestrade realizes how atypical this is, that twice now Sherlock has failed to predict him) when, without changing expression, Lestrade pulls up his own sleeve and sets his arm next to Sherlock's in the faded brilliance of the moon and the London lights through the window.

The scars stand out in shocking relief, silvery glimmer on the darker skin below, crescents of shadow at the base of each thin line. Sherlock's practised eye has seen so many scars that he is instantly deducing – faded, old, but deep originally, so deep that the marks never quite lost their texture, and deliberate, of course, not a dozen tiny matching accidents of fate from wrist to elbow, and the angle of the scarring – before he remembers that this is not a crime scene and that isn't the kind of answer Lestrade is waiting for.

Only it is a crime scene, set out in boldface on the soft skin of the inspector's inner arm, where the only bodies that lie scattered are the ghosts of the pain Lestrade didn't choose, murdered by the ghosts of the pain he did, and Sherlock can tell what the murder weapon was and how it was held and when it was done, but what he can't tell, what he still can't tell despite the control and the choice and the wealth of evidence laid out for him, is why.

Sherlock has known this secret of Lestrade's almost since they met, though it took him approximately six seconds to decide how it affects his police work and then to delete the information again, because none of his deductions mattered enough to make it worth remembering. At the time, it never occurred to him that something from so long ago might still mean something to his colleague on another level, and if it had, he wouldn't have cared. There is no room in Sherlock's brain for personal problems.

But now the why bothers him, and it isn't right, because knowing wouldn't be useful, and yet he still wants to, has to.

"Why?"

"I told you, Sherlock," his name again, Lestrade using his name, maybe because this conversation would never have happened with the real Sherlock Holmes, and he doesn't know where that Sherlock Holmes has gone or why this new one is living in his chest and asking questions that aren't useful, "sometimes, all that matters is that you choose the pain."

But that isn't what Sherlock meant at all. That's only the first answer, and it's dull, because it's the one Sherlock already knew.

"Obviously," he says, but it comes out scathingly and Lestrade pulls his arm away. Sherlock can feel it going, this tenuous connection in the dark, and he can't let it yet, because he doesn't know all of the answers. The chiaroscuro crime scene on Lestrade's skin is a glimpse of questions he hasn't thought of, which is beautiful, somehow, Sherlock thinks, and Lestrade has to stop being obtuse and answer them. So he catches the inspector's arm and holds it still, and everything is silent and surreal until he shatters it with words.

"Why did you have to choose?"

"Why did you take the drugs?"

So he could see, of course. So that he could subsume the sluggish, human mix of dopamine and serotonin in a wash of something more and better, so that his whole brain could come alive and he could escape for a few hours from the exquisite ache of his own physical constraints. So that the truth of his body mattered less, and the beauty of his mind could take its place.

He says so, and Lestrade holds a frozen breath as the words fall into the gap between them and catch against the scars, where the distance between their arms is too close for the things Sherlock says to slip away.

Lestrade thinks that the beauty of Sherlock's mind is sometimes too excruciating to bear.

"This wasn't for beauty," he says, the sinews of his wrist tightening under his own scars, shifting so that Sherlock sees the shadows dance across his disfigurement. "This was for the opposite. To look and feel as wrong outside as in." To write the stories of his pain along his skin, he would have said, if he could speak in Sherlock's poetry, to take the ugliness of torment and abuse and carve it into permanence. Because he was young, then, and he didn't know it could be better. But he can only feel those things, not say them, and he isn't quite sure how Sherlock, a brilliant, scornful machine, self-professed high-functioning sociopath, has made him speak of it at all.

"Wrong?"

"It seemed that way, then."

"The track marks are on my arms, not yours."

"My mistakes aren't any less wrong than yours," he says, knowing Sherlock will twitch at the word 'mistake,' knowing some part of him still believes the drugs are the right decision. "And I don't know what it's like to have beauty to let out. Most of us are ordinary, Sherlock. Dull." The man in front of him, one sleeve still pulled away from an elegant, marred forearm, already knows this. Lestrade is, after all, borrowing his words for the confession.

"Shall I tell you what it's like, then?" asks Sherlock, and he is suddenly pushing his other sleeve over his elbow as well, reaching for the recently-abandoned violin. "The beauty? Do you want to hear it?"

Lestrade doesn't know what he means, and can't gather an answer from the air around him.

"Shall I play you Greg Lestrade?"

Sherlock doesn't wait for an answer, just touches bow to strings and draws a note out into the room, one tiny shaft of silver light that drags across Lestrade like a blade across skin, and pain wells up like bright blood from the wound. Another, and another; without a word, Sherlock is laying him bare and open, only this time, the pain is good. And Sherlock is right, not only good, but beautiful.

Sherlock plays the moonlight, and the stark profiles of Lestrade's scars are less visible against its brightness.

It isn't a perfect substitute, but it will do.