Watching is Mycroft's life.

Mamma didn't know, of course. Mamma was much too busy with Sherlock, with his shrill whining and his precociousness - busy trying to find tutors for his violin lessons and governesses to look after him, since Sherlock's pale flat eyes scared off the ones with any sense.

Mamma and Father are very ordinary people, common people, not the sort of people who expected to have exceptional children. Mycroft knows that now, although when he was a child he could never understand what was wrong with them. Mamma is the one with looks - it's her dark curls that Sherlock has, and the shape of his eyes is hers. Father is from the stock of common solid Englishmen who overpopulate London. They're still alive; Mycroft has provided them with a nice house in the country and they've retired there, safe from their sons.

He remembers when he and Sherlock were still boys. Sherlock always threw the most elaborate tantrums, screaming and ranting in terms that oughtn't to have made sense to anyone - but they made sense to Mycroft, because he was quiet and listened, and learned to understand what Sherlock was thinking, how the pattern of his mind twisted, like a complicated cross-stitch that you picked up thinking you'd get kittens and roses, and instead finished up with a picture of a splintered table and a vein of red thread that illustrated some anonymous blood spill. Sherlock baffled Mamma. Mycroft had been such a good toddler, silent and wide-eyed, but Sherlock crawled everywhere and got into everything, tasted and touched and explored, and demanded his way.

He remembers Sherlock at five, uninterested in everything but whether or not he could make himself bleed with a fork.

He remembers himself at ten, watching his younger brother stab himself over and over in the web of skin between finger and thumb until the tines of the fork pierced through, and Sherlock didn't cry, didn't even look surprised.

He realised, then, that he would have to look after Sherlock, because there was something wrong with Sherlock, something that no one would ever be able to get a firm grip on, something inhuman and cold and terribly, terribly immature. Mycroft didn't move towards Sherlock, or speak, but he watched the blood springing up from Sherlock's hand in three equidistant places like a neatly planted row of poppies, and he became aware that he would have to watch Sherlock for the rest of his life.

Fortunately, their parents never paid any attention to him. Mycroft was much too quiet and collected for that. It was always Sherlock who was killing the pet fish to look at its gill structure, or leaving cake in his room to study the growth patterns of mould, or playing his violin like a prodigy. Mamma did love Sherlock's playing. She would stop everything else just to listen to him.

Mycroft listened, and watched.

He remembers when Sherlock was ten, and lit up his first cigarette. He remembers when Sherlock was twelve, and manipulated Kate Moran into kissing him in order to explore the progress of affection and how it could dissipate again. He remembers the disaffected way Sherlock called things off with her - "You aren't interesting." - and he also remembers, quite clearly, how he caught Lawrence behind the school building and told him that Kate fancied him, carefully nudging that relationship into blossom, so that Kate forgot all about Sherlock and the fact that she had been going to tell Mr. Brett that she knew he stole cigarettes and smoked them behind the school at lunch hour.

Mycroft remembers when Sherlock was sixteen, and shot up for the first time. By then Mycroft was at Eton, but he had already learned how to watch from a distance. He had a system for it by then; he got reports, some of them from Lawrence, who was still dating Kate Moran, and some of them from other people for whom he had done favours. He pieced together chains of events from letters and accounts - he had no shortage of those. When Thomas Doyle wrote to him to say that Sherlock was wearing only long-sleeved shirts to hide the track marks in his arm, Mycroft sat silently in his dormitory room and considered.

He could have told someone, of course. But that would have been messy, and while Sherlock doesn't mind messes, in fact thrives in his organised chaos, illegal substances in the oven and the personal effects of dead men strewn around his rooms, Mycroft abhors them. He refused to make a mess of that business, and he disliked the idea of alerting Sherlock outright to the fact that he was being watched. Mycroft was not the sort of person who overplayed his hand; he still isn't. He waited.

He let Sherlock go on playing his own dangerous games for a long time. The most foolish thing to do would have been to act too soon, before he had sufficient power. Mycroft had no doubts, even then, that he would have power. That seemed as certain and straightforwardly inevitable as the earth continuing to pass through the various seasons as Mycroft graduated and got his first government job and then his second and third, and travelled quietly up the road towards perfect control of everything that was of interest to him - in an official car, of course, because Mycroft disliked exerting himself and always has.

He remembers the first time he cut Sherlock off. He remembers that quite well. He didn't go himself, of course. Messy, dangerous. Mycroft worries about catching things he can't recover from, polio and meningitis and pathogens, HIV and AIDS from errant contact with some undesirable who will touch him for the briefest second and mark him for-ever. So instead he sent Carly, his first assistant. Carly was plain and when one looked in her direction one's eyes had a tendency to slide past her as if she weren't there.

She arrived ten minutes before Sherlock did, and when Sherlock stepped out of the alley at his contact point, his collar turned up and his scarf wrapped tight around his neck, there was no one waiting for him, no one willing to sell that snow-soft powder in the little plastic bag for the perfectly reasonable price of everything Sherlock had with him. When Carly described it later, sitting on Mycroft's plastic-covered armchair, she said that he had been furious, frantic even. Had kicked the wall. Shouted. Thrown one of those tantrums that always had Mamma running to smother him with concern.

Mycroft smiled.

The feeling of satisfaction that curled low in his belly felt as good as an afternoon of watching. It was the feeling of knowing that everything he saw was useful, that all it took was the careful application of the right pieces of information to finish half a dozen different projects for half a dozen different government branches - like sitting in a room full of newspapers and filling in the crosswords with practised ease, a word here and a word there until everything was complete, and knowing that he held all that directly within his brain, ready for him whenever he required it. He watched Carly squirming. She'd been working for him long enough to know that his smile could have a dual meaning. Mycroft forgave her, still thinking of Sherlock, and sent her home. He crossed one leg over the other, closed his eyes, and reflected - wondering how quickly Sherlock would begin to experience withdrawal, wondering whether he was already pale and sweating on the bed in his dormitory, wondering whether he was trying desperately to make another contact, or whether he had already found some other place to buy cocaine.

It wasn't important.

Mycroft remembers the first time Sherlock went to the hospital, a sick, thin young man of twenty, his forearms like connect-the-dot puzzles. He remembers why Sherlock went to the hospital, remembers the day he sent Robert in to install the security cameras in Sherlock's flat, remembers how Sherlock knew at once that something was wrong, and soon guessed at what it was, and then left the cameras in place anyway. He remembers the way his eyes would meet Mycroft's on the footage, how he would watch the tape and find himself staring into Sherlock's pale, flat gaze.

Sherlock knew, by then, that Mycroft had been watching for a long time. Neither of them brought it up. It just was. But sometimes when Sherlock had nothing to do he would hold staring matches with the hidden cameras, so ferociously unblinking that Mycroft wondered whether he were trying to get some reaction Mycroft couldn't guess at.

And he remembers when he turned on the circuit one afternoon and watched Sherlock tying off his arm, pushing the needle in like a scalpel into a corpse, smooth and surgically precise. Mycroft watched his expression change from tense to something less severe, the wrinkle in his forehead ease into smooth disquiet.

Sherlock never overdosed. He came close, but he always knew exactly how much his body would take and he acted accordingly. Mycroft just watched. But that afternoon he watched and watched as Sherlock lay on the couch with his eyes closed, the veins of his arms blue and thick, his hair damp with sweat, the sleeves of his silk shirt rolled up to the elbows, his stomach sunken like a starving man's, and Mycroft slowly got to his feet, went to the door, and called Robert in.

"Go call the hospital," he said evenly.

So Robert did.

Mycroft remembers that he continued to watch the cameras, watch Sherlock's dull breathing, which went on for a long time uninterrupted before the stillness in the tapes was disturbed by the clutter of the ambulance crew. Then Sherlock was gone, in a muddle of uniformed men. And for an even longer time, Mycroft stayed, watching the empty room.

But Mycroft knows the parameters of Sherlock's quick mind - he knows the way it twists and thrashes in captivity, he knows that it's like the proverbial rat in a maze, throwing itself headlong down every avenue until it reaches the door to escape - no more brilliant than anyone else, really, just remarkably quicker, so that he can calculate every possibility faster than anyone would imagine. Mycroft knew that then, and he knew what the hospital would be like to Sherlock.

Ordinarily he would have sent someone, but Robert was an unacceptable substitute for this. So Mycroft went himself, into that sterile bright place that bred every kind of disgusting illness, past doors that led into halls of rooms full of disease. He wasn't sentimental about it, of course. He wore gloves and had his whole outfit discarded afterward. But he sat down by Sherlock's bed and watched him breathe until Sherlock's pale eyes opened.

"So you've caught me," Sherlock said, very softly.

"Months ago," Mycroft said mildly.

"Of course. Now what? Off to prison with the naughty child?"

"What a waste of your talents."

Sherlock laughed. "Oh, yes, such a waste. Rehabilitation treatment, then. Mysteriously paid for by the British government."

"A waste of their money."

"What are you going to do to me, then?"

"Give you a little advice," Mycroft said, his hands folded on his umbrella.

"Yes?"

Mycroft looked at him, buried in regulation hospital blankets, an intravenous tube running into one of his scarred arms, his hair like spilled ink against the pallor of his skin, unmoving except for his eyes, which fixed on and followed Mycroft's movements like a cat watching a penlight. Sherlock looked small, and vulnerable, incapable - it was Mycroft's fault, in a way. He ought to have acted sooner, he supposed. But Sherlock would not have accepted anything sooner.

"Legal drugs, baby brother. I suggest caffeine supplements."

Then Mycroft rose from his chair, and left Sherlock.

The police, of course, did not disturb his brother. That would have been highly distasteful. They were alerted to the fact that routine drug confiscations should be performed on Sherlock's flat, but they were not to arrest him and they were not to give him any trouble.

And Mycroft went on watching.

Mycroft remembers when Dr. John H. Watson moved into the flat at 221B Baker Street. For the first week, nothing truly changed. Sherlock kept the same habits, made the same movements. Then, one day, Mycroft turned on the computer to view the circuits, and there was nothing.

Only darkness.

He thought about calling Sherlock, but Sherlock never answered calls - they went directly to his mobile. He thought about sending Anthea, seeing as she had already met the Doctor, but she was busy running other errands for him that were closer to her speed.

Mycroft hated - still hates - leaving his pleasant little office with its plastic-covered furniture and its little bottles of antibiotic hand gel. He's created the perfect sanctuary for himself, safe from the outside world with its sickness and its untidiness and its refusal to part like the Red Sea itself when he walks out into it with his umbrella in hand. From his computer he has the ability to check every single camera Robert has ever installed for him, to access every telephone line Sebastian ever spliced with his office landline, to bring right into his lap every record, every file, every tiny piece of information he has quietly arranged to receive. To leave all that invariably feels like stripping himself naked and stepping out into the streets: raw, exposed, out of his depth and his area of expertise.

Mycroft is a watcher. To go outside his office is to be seen instead of to see, to be viewed instead of to view. Messy. Dangerous.

But the cameras were gone, and Mycroft was not about to leave this business up to someone who did not know Sherlock intimately. He asked Thomas to bring the car, and then he extracted himself from his neat office and went into the disorder of London.

Sherlock was waiting for him, which did not surprise Mycroft in the least.

"Ah, the government man," Sherlock said, smiling the thin smile that pressed his lips flat.

"The government man," Mycroft agreed.

"Well?"

"Well what?"

"Are you going to take me to task now?"

"No," Mycroft said. "You dismantled my system. For the doctor?"

"Yes." Sherlock settled into his armchair, drawing the bow of his violin along his cheek, sliding it along the tips of his fingers as if they were the strings of a Stradivarius. "My own privacy - that's never been of concern to you. John is another matter."

Mycroft watched him.

Mycroft has never understood love. It isn't that he hasn't contemplated it; as motivators go, it's significant. But it's a messy thing, a chaotic thing, too prone to devolve into sex (sex disgusts Mycroft - slimy exchanges of bodily fluids, open pores, curious diseases that produce madness and parasites).

If Sherlock were in love - Mycroft watched him, settling the black umbrella he's so fond of across his knees. How curious. Sherlock had always been so asexual, so casually oblivious to the anyone's advances. But now there was in his voice something protective, however subtle. His pale eyes focused on Mycroft's, his face hard, the thin and jutting line of his chin and jaw clearer than ever as he tightened his lips again.

"I'll have them put back," Mycroft said.

"I know," he said. "I expected that."

"Is he so important to you?"

"He interests me."

"Interests?"

"Yes."

"One of your experiments?"

"No."

"Do you intend to keep him?"

There was a long silence, and then Sherlock said, "Perhaps."

"It doesn't change the situation. Not at this time."

"I'm aware."

"Good."

"Hullo, Sherlock - " They both turned as the Doctor appeared in the doorway, in his worn-out jacket with the leather patch on the shoulder, a litre jug of milk in his hand. "Oh, sorry. I. Sorry." He started to back out of the room, but Sherlock smiled at him. It was the same tight smile he had given Mycroft, but this time there was something warm in it that Mycroft had honestly never seen in Sherlock before, in all his years of watching.

"No, no, come in. Mycroft is just leaving."

Mycroft stood. "So I am. The situation remains static, then?"

"For the time being."

"All right. Good afternoon, baby brother."

Sherlock ignored him, rising to take the milk from the Doctor - a cursory glance would have made it look as though Sherlock were simply retrieving his prize, but Mycroft could see the way his long fingers lingered on the Doctor's forearm for exactly two point seven seconds longer than necessary, the very fact that his grip didn't make the Doctor wince. He didn't look up as Mycroft went out the door.

Mycroft had the cameras reinstalled-has them reinstalled, in fact, every week, as Sherlock locates and dismantles them, sometimes leaving a message for Mycroft and sometimes not. It's merely a formality, as Mycroft sees enough to keep an eye on his brother; but the cameras in the Doctor's room are always the first to cut out.

Then, one evening, Mycroft turns on his computer and pulls up the circuits for Sherlock's flat, and finds Sherlock sitting on the couch with a piece of rubber tied around his upper arm, sliding a shining needle into the dark vein in the crook of his elbow.

For a very long time, he sits still and remembers.

Then he calls for Thomas and the car, and watches the lights reflected on the rainy streets as he drives through London. It's a tedious journey, takes too long. The traffic irritates him, but he doesn't ask Thomas to hurry. There's no use in hurrying.

Thomas pulls to the kerb in front of Sherlock's flat, and Mycroft gets out and climbs the stairs, opens the unlocked door (of course unlocked) and goes to the couch, where he sits, and, for the first time in his life, gathers Sherlock into his arms.

Sherlock buries his face in Mycroft's shoulder. His white hands knot in the sleeves of Mycroft's thick coat, and he slides to his knees, his shoulders shuddering, holding as tightly as an infant grasping a finger. Mycroft strokes his hair. He can't help it. He doesn't like to touch other people, doesn't like the possibility of what they might transmit to him, because nothing is sterile enough to make him happy. But Sherlock is all but weeping, and he feels as small and frail to Mycroft now as he was in the hospital, and Mycroft can almost see the intravenous running into him, his dark hair spread out in the pillow, dressed in nothing but a blue cotton gown, a symbol of the unwell.

Mycroft holds him close.

"What happened?" he asks softly.

Sherlock, who has something cutting to say about everything, shakes his head wordlessly and knots his hands tighter.

"I'll change it," Mycroft says. He has, after all, arranged for most of the accommodations in Sherlock's life. It's his responsibility. He's the watcher. "Tell me."

"No," Sherlock says hoarsely. He's not so high, then, that he doesn't understand.

"What happened to you?"

"Nothing." There's an undercurrent of anger, feverish and frustrated. Mycroft strokes his hair again soothingly.

"Where's Dr. Watson?" he asks, realisation dawning - Sherlock is alone to-night.

"Nowhere." That same undercurrent, revealing the problem clearly enough. Sherlock is ordinarily too clever to make that sort of mistake, to open himself to Mycroft, so the cocaine (the fucking cocaine, Mycroft thinks, so genuinely angry for a moment that his usual encompassing composure gives way) has affected him. Or perhaps he's just throwing another of his tantrums.

"A woman?" Mycroft asks.

"A woman," Sherlock says, disgusted. "A woman! Why the hell would he want to see a woman? She's so ordinary, she's dull, she's simple, I could define her in under five key terms! I could dissect her and label every organ in her body! What the hell is he doing?"

"He's left you alone."

"Why should I care? What does it matter? It doesn't matter. It's all pointless. If he wants to do something as mediocre as taking off his clothes and putting his cock into some woman, that's his own business, isn't it? Not mine."

"Shhh," Mycroft says. He's never done this before. He's always stood back and watched Sherlock - interfered, yes, certainly, but never touched him, never touched the problem itself with his ungloved hands. "Come here. I'll sort it out."

"Oh, you'll sort it out, won't you? Spying and watching like fat sphinx, keeping us all out of Thebes. What do you do with the people you catch, eat them? Hearts are high in cholesterol, you know, and you should be watching your diet." Sherlock's body quivers; he's been trembling with the same ferocious energy since Mycroft arrived. "I don't want your government magic to touch him. He'll wake up with wires in his body unless he stays in my flat, or a camera up his fucking arse to keep an eye on everything he does, I know how you work."

Mycroft purses his lips. Sherlock's right, in a way, although the cocaine is making him crude. But of course Mycroft had considered drawing the Doctor aside for a frank conversation, much as he has considered sending someone to find out who the woman is and arranging for a sum of money that would encourage her break off her relationship with the Doctor.

"I know what you're planning," Sherlock says accusingly. "Threaten him, bribe him. Take away his job if he doesn't stay. 'Oh, Doctor, someone has to look after my poor brother, he's come to rely on you', sell me out for your own satisfaction, you smug bastard, with your cameras and your wiretaps and your fucking drug busts, you think I don't know how Lestrade gets his tip-offs? Buy John's soul before he knows what's happening."

"Hush."

"I won't fucking hush!" But he clutches Mycroft tighter, trying to struggle to his feet and failing; he slumps back into Mycroft's arms.

"Lie down," Mycroft says. "Let me clean you up."

This time Sherlock doesn't answer. Mycroft eases him onto the couch, kneels beside him and unbuttons the sweat-stained silk shirt. He navigates Sherlock's deplorable kitchen and brings back a wet cold towel to bring down the feverish heat of Sherlock's thin chest and angular face, bathing him carefully. All the while, Sherlock watches him with dilated pupils, eyes flickering like the reel at an old-fashioned film showing.

"It's not like you to meet with someone on his own terms," Mycroft remarks, after a while.

"They're my terms." Sherlock is fading fast, any leftover lightness in his eyes dissipating as the high winds down. With this Mycroft is familiar: the sense that as the cocaine wears off Sherlock empties out, until he's only a fragile golem of pale skin, filled with air and brittle bones and little else.

"And yet you won't allow him to be coerced into staying with you. You want him to make the choice on his own."

"No. I want to coerce him myself. Not you."

"Then why did you do this when you knew I would see you?"

Sherlock grits his teeth. "It doesn't matter. You don't fucking matter, don't you understand? I'm not sitting here waiting on your every movement, waiting for you to swoop down out of the sky and save my skin every time I put a toe out of line. It's my own life, if I want to put the needle in my eye I'm not waiting for your God-damned say-so."

Mycroft winces. Even knowing that Sherlock is trying to bait him doesn't smother his disgust at the thought of a hypodermic piercing the posterior epithelium, entering into the vascular tunic. "Sherlock," he says. "Let me bargain with you."

"Why should I make bargains with you?" Sherlock's lip curls. "Because you've been as naughty as I have? Because Mummy's pretty little china heart would break if she knew you were as bad as I am?"

My croft ignores him. "No more cameras on your doctor. No reports to me on his movements. I'll have the tap taken out of his mobile."

"In exchange for what? Slavery? His first-born? Is the Empire in danger so boringly that I wouldn't take the case otherwise?"

"No more cocaine," he says, far more gently than he meant. "No more. And I'll take all surveillance from the doctor."

Sherlock's face twitches. "Should we cut our palms and grind them together on a blood-oath? I can give you my diseases. Just think, Mycroft, I could transmit my intellect to you like a pissing venereal illness. Then you'd be the one dying."

"The offer will stand. Any time you choose to take it. Don't be a fool."

"Don't take me for one." Sherlock closes his eyes.

Mycroft gets to his feet and takes the towel into the Doctor's room, where he knows the laundry hamper is. When he returns Sherlock is in the same place, and Mycroft sits down, settling him back into his lap. At first Sherlock lies like a dead weight, but then his body shifts slightly, and by the time Mycroft falls asleep, Sherlock is clinging to him again (and Mycroft wonders, for the first time in his life, whether Sherlock has ever wanted anything from him, or whether they've both known, without ever speaking, that the watching is the best gesture of love he has to give).

In the morning Sherlock is sober and irritable, and Mycroft has a stiff back and a wrinkled suit. Moreover the Doctor is back, and Mycroft lets him deal with Sherlock's black mood; he himself has responsibilities that have been neglected for nine hours too long, and he calls for Thomas. He needs a shower, disinfectant, clean clothes, his personal physician-on the off chance he scraped himself on Sherlock's needle he wants to know immediately and address any consequences. He's tired of the unpleasant flat and the disorder and his temple is throbbing from the uncomfortable sleeping arrangements.

For a day, he doesn't address the problem of Sherlock; he concentrates on other problems, simpler ones, whom to have killed, who to promote, whom to employ under what name. But on the second day he has the cameras reinstalled in Sherlock's flat, in every room as usual.

Every room but the Doctor's.

When he plays back the footage in the evening just before he leaves his office, his computer screen is filled with Sherlock's face. Sherlock is standing on a chair, eye to eye with the hidden camera, watching Mycroft through layers of technology and invisible electrical signals.

His voice is fuzzy and far-off, slightly indistinct, but Mycroft can still understand what he's saying.

"I've taken your offer under consideration."

Then he sits down in his armchair, sets his violin under his sharp chin, and begins to place, long fingers grasping the bow tenderly. It's a song with which Mycroft is unfamiliar, one which holds no meaning for him, but Sherlock closes his eyes and plays with the same intensity he puts into his work, the taut lines in his throat and collarbone standing out, as statuesque and aesthetic as any sculpture (the genuine soft flesh of a Bernini, long-limbed and fragile as Michelangelo's Pieta). He plays until there is nothing but the music. He plays the way he thinks. He plays until the Doctor comes into the room, mild face warm with wonder, and says,

"That was magnificent."

Then Sherlock smiles.

And Mycroft watches.