Three days ago, in an East End interview room, a suspect asked the officer in charge of his case if, and I quote, 'the great Sherlock Holmes' had had a hand in his capture. The policeman in question said no. He lied. As a matter of fact, Sherlock and I were on the other side of the mirrored wall, watching all of this, hearing it. Me, I laughed at it. And why not? It seemed such a ridiculous thing to say. Childish, almost. I tipped my head to say to Sherlock, "If only he knew, eh?"

All I got in reply was the closing of the door. I hadn't even felt him go. I followed, of course; damned if I was going to stay for the rest of the questioning. The case was solved. I had heard it all right there on the crime scene where, par for the course, Sherlock had cracked it in under three minutes. Why should I hang around and listen to the proud confession of a disappointed lunatic? The case hadn't exactly been remarkable. Nothing to get excited over, not the next reader sensation for the blog. Pretty much your common or garden…

Oh, look, surely you know enough by now not to hold it against me if I use the phrase, 'bog-standard multiple murder', don't you?

So when Sherlock left, I presumed he'd heard all he needed to, and I followed. But he was ahead of me, and wouldn't slow down. By the time I got to the street he was already stepping into a cab. Didn't wait, and left me there wondering.

You haven't heard about any of this. You haven't heard about the case, because there was a car bomb on Threadneedle Street the same day, so it didn't make the news. You didn't hear about it on the blog because… Well, we'll come to that because.

I got the next taxi (eventually) and went home. Presuming I'd find him there, I walked through the door, "This had better be good, Sherlock; it's raining out there." But he wasn't there. Hadn't come back. Tried texting, got no reply. As the day wore on and on it started to annoy me. I'm sure you can understand. The idea of just taking off, without a word… I don't get surprised anymore, but it does still irritate me.

I wasn't worried. Sherlock's reactions to the solution of a mystery, while the specifics are unpredictable, are never great. You don't need medical training to understand. It's the mental and physical exhaustion, his refusal to eat or sleep while he's working, not to mention the strain when the thing he's working on, which has so totally consumed his mind, is complete, and suddenly folds. So annoyed, yes, but not yet concerned.

It was after six when Mycroft rang. Sherlock wasn't answering him either. I said, in the interests of friendly warning, "I'd leave him alone, if I were you. He had a case for all of two hours this morning and-"

"And he hasn't come back yet, has he, John?"

"How would you know that?"

"Do you remember what I told you, after Lestrade's little raid?" Yes. About Sherlock, and who he was before I knew him. About all the things he's moved on from. About how some fights are never won, and must be fought each and every day as long as he lives. About what to do if there was any danger of his losing.

But I never got the chance to search the usual places. That was when Sherlock walked in, coat buttoned, hands in his pockets. I tried to tell him, "Your brother's on the phone." But he swept clean on through the other room and slammed the door.

"Keep an eye on him, would you?" Mycroft said.

"Why? I don't understand."

"You could be absolutely right."

The words, on paper, they look like he was conceding the point. In reality, in tone, it sounded like he was humouring me. Once he'd hung up, I put the phone down and went to the bedroom door. "Sherlock?" No answer. "Sherlock, for God's sake-"

Mumbled from within, something that might have been, "Sod off."

I tried the handle, but the door was locked. What could I do, then? How could I even broach the subject, through a door, without even looking him in the eye?

Those were long, long hours I spent there. Without the television, without the radio, without even boiling the kettle. Just in case he spoke, or in case there should be any other sign that he needed me somehow. I fell asleep, in the end, in the armchair. That must have been when he emerged. I think he tried to eat something; found an abortive attempt at a sandwich on the worktop the morning after. A mug left out with the coffee already in it, just that the water was never poured.

He'd moved to the sofa. This is two days ago.

Sitting sunk in the corner, pressing into the cushions like there was comfort in them, resting his head on his fist. Staring ahead. Silent.

There's not a lot else to report. Since then, he has moved twice. The first is the reason you've never read about this. I mean, don't get wrong, I started to write it up. Had to post something, after all, and it can't just be successful case after successful case now, can it? However much Sherlock might want it to be… Anyway, it was as brief and boring a piece as you might expect.

"Sherlock?" I asked. He responded, too. Turned his head and everything, as if he might deign to answer, if the question were up to scratch. "What the third thing you said about the bloody fingerprint on the Venetian blinds? I've got the height thing, and the point about exhibition, and-"

And then he got up. I thought that was a good thing. But then I'm not as clever as he is, am I? He got up, crossed the room in three determined strides, and grabbed the plug out the wall. Then turned the laptop over on his hand and took out the battery, so that everything was lost. This, all, with calm efficiency. Then he returned to the sofa, and since then he hasn't even been reacting when I try and get him to speak.

He moved this morning too. I didn't see it. I got fed up with it all last night and went to bed. But when I came down this morning, his position had changed, and there was a stained, empty mug on the windowsill I hadn't put there.

Of course, I've learned better than to assume that this is a good thing. I skipped right past the movement, the attempt to ingest anything, and went direct to asking myself what could have held his attention at the window in the night.

He doesn't look well.

…Obviously, he doesn't look well, he's not eating or sleeping, but that's not what I meant. He's unshaven, still wearing the clothes he sat down in, sunken eyes, but it's more than that. He slouches, as if he's carrying some great weight across his shoulders. I have tried asking him to explain to me, but it's like he doesn't even hear my voice anymore. I'm this close to calling Mycroft back, telling him there's something deeply wrong.

Again, he doesn't give me a chance to get to desperate measures.

"Forty-two," he says.

Very much doubting he's been working out the answer to life, the universe and everything for three days, "Beg pardon?"

"Forty-two separate indicators. Forty-two times I blinked and missed everything. It's obvious. The closed blinds were the giveaway. Then there's the note under the carpet, not hidden enough to stay hidden, the changing of the woman's clothes post-mortem, the blue ribbon on the wrist… Forty-two. The moment we walked on to that crime scene I should have walked off again, rather than give that bastard his wish."

I'm not sure I've ever heard him swear before.

"Hindsight's useless, Sherlock."

"Hindsight is hell. You don't need to remind me."

That wasn't what I meant. He won't let me explain, but it's not what I mean. That's why I'm just sitting here, why I can't even speak, as he gets up, grabs his coat and goes out again exactly as he is. I still don't know where.

The murderer. The murderer who requested him specifically. It made me laugh. That's what's done this to him and it made me laugh. That crime was committed for him. Those people are dead for him. Or, as is apparently the case in Sherlock's head, because of him.

As hard as I've been trying to put it off, that's how fast I get Mycroft on the phone. "You knew," I tell him. "You knew the reasons behind this, before he ever even came back here. Why didn't you tell me?!"

He doesn't answer right away. Maybe because I'm shouting. Maybe because he doesn't have an answer to give. "Would it have made a difference?"

"Of course it would! I… I could have spoken to him at least."

"And what would you have said?" Something, rather than just sit here guessing at him all this time, not knowing what to do or if there was anything I could do, at least I would have known. But what would I have said? Specifically? Word-for-word? I don't answer, because I don't have an answer to give. "John, in recent years my brother has gone to extraordinary lengths to be… self-contained. The deepest recesses of Sherlock's heart are nothing to do with the man himself. They
are triggered only when that containment can no longer hold. When some part of him, quite without his permission, has lashed out into the world and had some effect over which he does not have perfect control. That's when he gets hurt. There, now. You've had your explanation. You know the details of the case. What would you have said to him?"