John's on Westminster Bridge, leaning on the painted iron railing.

Just to get this straight at once, he is not thinking about jumping. Sherlock's death is still indigestible in his being, but not (tonight anyway) the corrosive poisonous pain that blacks out John's vision. Right now it's more of a concrete ghost along his back and shoulders, weighing every movement of his body. His mind is clear enough but he's so tired, carrying his loss everywhere, having to fit it into every cab he takes (Sherlock tended to avoid the tube) and find it a seat with him at every table (though Harry's flat has always been free of everything but a whisper of Sherlock's disdain and Harry's naked growling animosity toward him, never mind how rarely they'd met).

John walks to find some rest. He sleeps better when he's truly tired, and he aches less when his body is honestly distracted. London has been part of his life since he was old enough to take the train in with his schoolmates (accompanying the real geeks to Forbidden Planet ); he became part of London while he was a medical student, not that he had much time to enjoy it. After Afghanistan, those first couple of months, it was a cold noisy place, starved of sun and oozing damp into every ache the war had left in him, but still so alive.

And then, Sherlock.

Mycroft thought that walking with his brother was to see the battlefield; but the battlefields in Afghanistan were not the pitched battles of older conflicts. They included people, neighbourhoods, shopkeepers, parks, the blurry outline of history repeating itself or doing something briefly new. Sherlock's London was very like that. At times their days had echoed to John particular moments in a city or a village where the army or its translators had had friends (yes, also the ones where someone shot at them from an alley). London with Sherlock was like having a native guide with friends among all walks of life: people for whom he had done some favour or other, or asked one; the people mostly without power or influence who painted their faith in him on walls now, or offered John an unexpected drink or biscuit, or once rather strangely insisted he take their seat on the bus.

Sherlock gave John a city of layers, threads of the past that still wove into the living story. He might delete the Copernican system (John saw that come and go more than once), but the blue plaques that marked a place or a person significant in time provoked a series of remarks and usually caustic opinions. Sherlock's scattershot enthusiasm delivered a running commentary on their surroundings that might have spawned another colour of plaque entirely ("Cellar of that house? Last real craftsman counterfeiter I encountered worked there. Amazing engraving, wasted on the paper he used, really —" "That café? Owned by the nicest poisoner, you'd have loved her, John—").

If it had been difficult to consider leaving London before Sherlock, he knew he never could, now. As much as the memories ached or stung, he saw the streets and doorways through his friend's knowledge of the city, like Sherlock-colored glasses. Possibly unlike Sherlock, John knew the familiarity, the detail, was love.

So John liked to walk, for the parts of town that held or did not hold these memories; for the motion itself, easing the places his body held the emotions he preferred not to examine; for the icons and landmarks so overused they were almost empty, passed unnoticed by thousands to their own destinations. For the changes in light: gritty early morning mists giving way to spitting-down lunchtime rain or buttery relaxed late afternoon, to sloppy distracted evening, full of City people leaving and suburban people coming in for all that London offered; to lambent cloud-lit soft drizzly night; or most rarely, to a night with the sky so dark it consumed all that human ingenuity could throw at it, still dark, and the strongest stars showing themselves to whatever few looked their way.

It's something like the last of those tonight. Jupiter has pulled itself out of earth-glow, over the water now. The sky is black, and the Thames running to meet it shines like tar sprinkled with sequins. So late at night, he probably shouldn't be out; he has work the next afternoon. But it's just hours at the surgery, not The Work. Which is not, John completely realises, his work. It was always Sherlock's even though John never felt so perfectly where he belonged as when he ran at Sherlock's side, not even up to his wrists in blood in Afghanistan. That had been John's work, perhaps, but without the joy.
These weeks, when he would have welcomed the exhaustion and the focus of real battle and real wounds, he's felt remote from everything. No urgency to chase without the game afoot, no satisfying climax of a fight or a cascade of deductions… unsettling to realise how much he'd been nourished, exhilarated, from the same sources that Donovan had told him would lead to a crime scene of Sherlock's very own. John couldn't do it himself, but it had not been insignificant to conduct the light Sherlock untangled—crushed—cohered into a laser.

The wind changed from barely a whisper to a warm riffle, a gust that moved in his hair; from a whiff of low-tide mud and petrol to a different not-quite stink of saltwater and coffee, diesel and bananas, chocolate and fish guts. Or that might have come from the woman who now stood next to him, a dark outline, taller and perhaps broader than himself. John thought he felt her warmth radiating through the inches between them. Despite the wind that had gasped once, the air now was almost still; the only noises coming to him were those of the water below.

"John Watson," said the woman, "the tide of your sorrow has turned. You do not drop your tears into my waters tonight."

It speaks for his life that this is in no way the creepiest thing that's happened to him lately. Nigerian accent, many years' fluent in English. Neither frightened nor frightening. Formal but remorselessly familiar. She reminds him, actually, of Mycroft, without the edge of sinister. Mycroft has an agenda. This woman simply is. And she's right; John's heart is not healed but he is almost aware, now, that his feet can touch the bottom. The waves of grief still batter him but it's becoming clearer he will not drown there, even if that sometimes still looks attractive.

"It's not for you to follow where he's gone, not yet." The trick of answering John's unspoken thoughts is hardly new to him. He's ignored the amount it annoys him so often it really doesn't, now; or it may be the peacefulness of the night has entered his heart.

"I miss him so much," John says.

He feels the depth of her sigh. "I miss him every time he leaves. As I feared we would miss you."

"You don't know me—"

"The Companion with a Thousand Faces? Of course I know you."

John's inner sane man (he knows most people have one; he hopes, on the whole, that most people listen to theirs more often than he does) quietly moves the woman from a Mycroft-flavoured column to one marked 'Whacko.' Not the same one as Moriarty by any means. More of a Hyde-Park-Corner, Professor-Trelawney, mostly-harmless column. But in himself, in this moment, John-who-is-beset-by-all-comers, the one Sherlock loved to poke and who gave as good as he got — John-in-the-experience doesn't judge. He wants to know more.

"I cannot tell you more. You already know that your heart must work with your head, that you find both of them in your hands. It's good your eyes are clearing, for you are not done needing them, and nor is he."

"He can't need anything anymore." At that the sorrow flushes back into John's throat. He can't need me.

"His work is far from finished."

"Is Moriarty still out there, then?"

"Does that matter? His work is far from finished either."

A criminal web with a thousand radiations— "That's not my work," John says. Mycroft's. Maybe even Lestrade's. Because, he doesn't even need this woman to tell him, they've done such a good job so far. But John has no idea where to pick up the thread. Well, the kidnapping, perhaps. You know my methods.But John can't see himself doing anything but plodding blindly over the same ground Sherlock had read, flawlessly, while running at top speed. "I can't do what he did."

"Then do what you can."

Well, that's unfair. Not what he signed up for. Alongside his sorrow John lives with bitter anger at his friend, the one it's so much safer not to look at. He managed well enough with the death of friends, comrades, trusted officers in his Army days; he'd tried to counsel others who felt the same as he did, broken and furious at the dead for leaving almost as much as at the ones who had killed them. Sherlock had been more to him, in less time, than any of those; but his killer was the same man as the one John had loved. The heat of his rage threatens to burst out, to cover the landscape of his mind with ashes and burning, broken glass. (It's just what Ella's looking for, but he doesn't trust her with it either.) John can't begin to deal with it, and this strange woman is demanding he deal with an enemy no one has managed to lay hands on. Part of him snaps.

"Why am I left all alone to make up my mind what to do?" The words don't feel like his, but the feelings do.

She taps him, not hard but chidingly, on the cheek. "You are the man Sherlock Holmes could not do without."

"He stepped-he leaped— off that building. He left me, us, to do without him."

She shrugs. "You can only judge what you understand. If he had left less cruelly, would you be any more capable?"

"I'm sure to go wrong." John wants to sulk, but years and years have taught him nothing is worse. No anger more deadly to friendship than disengagement. He sighs. He's lost this argument.

"You said he gave you so much; would you throw it back in his face?"

She has no right to say such things. But she has the right of the situation. "No." John is an eight-year old again, wanting to shuffle his feet.

"'No' what?"

"No, ma'am, I don't want to throw it in his face."

He sighs.

"Better."

It is better. Some of the weight on John's bones has lightened.

"You may call me Mama Thames if we meet again. Look at me—" and she kisses his forehead, terrifyingly close. John feels like someone's sluiced a handful of water down his back, and shakes it off, and is alone on by the railing once more. He wonders about psychotic breaks and what the hell was in that beer he drank hours ago; and he goes back to Harry's to sleep, deeply and without any dreams he can remember the next morning.

A few days later John's taken to see Mycroft again, somewhere more public than the Diogenes Club, more suitable for a low-level functionary in Her Majesty's government (he swears he sees Sir Humphrey Appleby go past). Once again, it's not the time to take him by the throat and slam him against the wall; but maybe someday. Right now it suits John's purposes to use and be used by Mycroft; he squares his shoulders and goes into the building.
The door to the office where Anthea has sent him this time opens, and out comes a strikingly handsome woman. She's dark and tall and slim, with black eyes slanted like a cat's and an air of entitlement so thick she nearly walks through him. John smells cigars and new car seats, horses and furniture polish, Stilton, Belgian chocolate and behind it all the hemp and a crowd like a Roman circus. She stops and looks at him hard.

"Oh," she says. "I thought you'd be taller."

"So did I," says John.

She makes an inarticulate sound of dismissal and disdain, possibly more cutting than Sherlock at his worst, and departs without another word.

Mycroft, in his office, is looking oddly harassed, a sight that would fill John with delight if life felt more secure these days. "Posh bird," John remarks, hoping for response . Mycroft's agitation — too strong a word — the ripple in his calm sends out more rings.

"Lady Cecelia Tyburn Thames. The most dangerous woman you will ever meet."

"I did share a flat with Irene Adler for a few hours, you know."

"Who was proven, incontestably, to be a mere mortal like the rest of us. Stay clear of Lady Ty. A dominatrix may cause trouble, but Lady Ty's a politician."

John grins at the venom the word offers from Mycroft's mouth.

Mycroft's calm is reasserting itself now; he can accept incoming data once more, and from the look he gives John, he's getting some. He leans across the desk and sniffs. John wonders whether the thinnest thread of bananas and diesel in the air is his imagination or not. "How on earth did you come by the blessing of the River, John?"

"If I had the slightest idea what you were talking about, I might be able to answer," John told him. "Is it like being an Elf-friend?"

Mycroft's gaze rakes over him. "Fools and children, I suppose. Now, John, who's following you these days? Besides my people, of course…"