A/N: I dunno I guess I just really like the idea that Sherlock has massive PTSD but won't tell anyone? Follows directly after the final scene of TSoT.

As he left the reception solitude seemed to settle over him like an old, familiar blanket.

Warmth of the Belstaff over his shoulders - he'd missed this ridiculous coat - and the enveloping stillness of the gardens surrounding him, silence punctuated only by his own footsteps. The muffled noises of John's wedding had diminished with distance, muted to such a level now as to seem unreal. A figment of his imagination, perhaps. Easily dismissed.

The suit and tails left him feeling overdressed and foolish out here with the quiet and the trees, but he had nothing to change into and so did his best to ignore it. Patted down the pockets of his greatcoat instead. He'd promised himself he wouldn't bring them, but... ah, yes. A pack of smokes and a lighter. As usual he'd subverted his own rules.

A quick, practised movement had an ember going. Muscle memory, reinforced by having fallen back into the habit during his self-imposed exile. Twenty-one months almost to the day, now, counting from the precise moment he'd started again. Nearly two years... christ, had time really moved so quickly? Betrayed by the steady march of a clock yet again, always managed to take him unawares.

Years ago, but he still hadn't been able to delete that half-minute he'd wasted. Dallied for ten or perhaps twenty seconds before taking off running. Too late he'd skidded to a stop on the edge of a high embankment, sweat soaking through his shirt in the humid air, shattered burst of a gunshot ringing in his ears. Below him red and pink and black and jagged shards of white splayed out in a halo around the empty space a girl's head had once occupied.

She'd been around ten years old. Just a filthy beggar child off the streets with a penchant for eavesdropping, he'd initially secured her assistance in return for a handful of change and a chocolate bar. Over his next days spent in the city she'd taken to turning up in his shadow at the unlikeliest of times, all smiles and outstretched palms, nagging him incessantly for more food or money or sometimes simple companionship. What information she provided often proved useful, her presence not unduly irritating, so Sherlock had come to accept her trotting merrily along after him through the open markets as a matter of course. She had a decent sense of humour, good memory, budding talent as a spy. Despite himself he'd almost grown to like her.

Those warped seconds, then, staring at the blood-stained, faded floral pattern of her shirt, the colour draining from nut-brown skin... she'd never again pop out of nowhere like a mischievous ghost to accost tourists for handouts, a disgusting mange-ridden stray dog trailing along in her wake while she sang stupid made-up nursery rhymes at the top of her lungs. Those smears of colour seeping into the parched dirt were all that remained of a vibrant human mind. That mass of crushed bone and torn skin had once been a mud-streaked face with a crooked, gap-toothed smile... he couldn't even tell where the eyes were meant to go now.

And for the first time since leaving home, something inside him cracked. All at once it wasn't enough to name himself a sociopath, carefully ignoring the twinges of feeling which would insist on proving otherwise. For a fleeting instant he merely stood horrified and uncomprehending as any other human being in the face of endless looming darkness. The enormity of his task... the futility of it all. This child had died for the sake of a few pointless scraps of information. How many more like her would it take to topple an empire?

One, then two halting steps backwards, away from the dry ravine where she'd soon be buried by flood runoff. Her grave. The shooter had fled immediately. Sherlock hadn't paid him much heed, knowing he'd be hunting the man down anyway. Not for revenge, of course, but necessity - this branch of the organisation needed to be eradicated completely or they'd just find new recruits and start the whole thing over. Every one of them had to be either arrested or killed before he'd allow himself to move on.

Finally Sherlock's legs did their job of turning him round and he walked, dazed, numb, his chest feeling oddly hollow, back towards the crowded city centre.

Picking up a pack of black-market Camel knockoffs hadn't really been a conscious choice. By the point of finding a lighter, however, he'd known full-well what he was doing. Gone almost a year without smoking, at the time. Personal record. He gave it all up with a flick of a spark and the acrid smell of burning tar.

Diminished tolerance made the first drag come on far too strong and he coughed, hard, doubled over against a fence railing. But he straightened himself back up and soon remembered precisely why he'd developed such fierce dependence on these foul things in the first place. Nicotine settled like a soft, familiar cloud over his brain, slowing racing thoughts and covering up all the things which hurt too badly to process.

Two fags later, he could cope.

Three... and he could fight.

A mid-sized waystation of Moriarty's international crime ring collapsed a scant few days later. Crew and headquarters alike thoroughly and mercilessly dismantled. The work of at least ten men, untraceable, no one had any clue what had happened.

Start to finish it had taken twenty-eight cigarettes.

From that point on he'd always kept count. Portugal took thirty-four, Germany just five, Romania eighty-six. Time's steady march had failed him, stole precious seconds away when he'd not been looking, so he found a new way to quantify how much of his life was lost. Four cigs, twenty cigs, a hundred.

And tonight... John's wedding. One cig.

Sherlock stared at the ember glowing softly against the darkening night. In the distance he could just barely make out the sound of music. John would be dancing with his wife... they'd be happy. They were happy. Plainly had been for quite some time, in fact, a warm budding romance to replace brittle friendship. And Sherlock still couldn't quite believe his luck at having been allowed to share what he could of their companionship these last few months, even after all he'd done. Any sane couple would have shut him out the first chance they got.

A child, though. That changed everything. They'd need to focus their efforts, their... love... on the infant. Minimal distractions would be best. Mary should avoid as much stress as possible whilst her body did the work of two, and John would want to invest every resource into forging a strong bond between them. Tomorrow the two of them would leave for their honeymoon, the first step of that process. John had asked Sherlock to update the blog for him, but after that... what? What was Sherlock meant to do?

Remove himself...?

Yes, that. Precisely. Best plan in the long run, wasn't it? Non-interference. No better way to avoid stress than to avoid him, after all. Sherlock would retreat to a safe distance, eschew all non-essential contact with them, give the new family space to blossom. Then, when John was ready to handle the strain of putting up with the ridiculous man he called his best friend, he'd say as much. Come round the flat, maybe. Ask where Sherlock had been, why he hadn't called, see if he wanted to get a Chinese.

Or... alternatively, he might not even acknowledge his absence. Forget Sherlock had ever existed. They'd drift apart and never speak again. End of an era.

Sherlock flicked a bit of ash off his cigarette but didn't take another drag. Just stood and watched the smoke coil around his hand, up his sleeve, snaking round his trouser leg. The sharp scent of burnt tobacco would seep into the expensive textiles before much longer. His coat would smell like an ashtray.

That thought was enough to get him to lift his hand, prop the cig between his lips like he used to do when he was younger. Easier to wash the stench out of his hair than scrub it off thick wool.

An idle glance back the way he'd come showed the decorative garden shadowed and empty. In a kinder world, perhaps, someone might have followed him. This world was far from kind, and he wondered instead if anyone had even noticed he'd gone.

Likely not. And even if they had they plainly didn't care. Not enough to come after him, in any case. But that was just as well, really. This was John's night; his and Mary's. Sherlock's part had been played. He'd done all they asked, filled the role expected of him - been sociable, outgoing, tried his best to behave like a normal human being. John deserved the effort. Even if the act exhausted Sherlock's mental reserves straight down to the core and made him feel a transparent fraud, squirming and uncomfortable in his own skin.

But it was fitting, wasn't it? To have spent the day playing a role so antithetical to his nature. Like a final performance. Farewell to this era of danger and heartbreak, key player sent off with a flourish, then on to love and familiarity. Happiness.

John's wedding: two cigs.

Calling a cab to meet him at one of the buildings would draw too much attention to the fact that someone had chosen to duck out early. And despite the faint twinge in his chest seeming to have been clinging to a tiny spark of pointless hope for the sight of a friendly figure striding down the path in his wake, Sherlock found he couldn't really stand the thought of anyone taking it upon themselves to comfort him. They'd see in his behaviour the worry of being left behind by John, would doubtless offer some trite reassurance that it wasn't quite so bad, really, they'd still be friends. And that was fine. Friends, yes, he'd like to keep hold of the few he had. Perfectly reasonable to be upset about that.

No one would see the halo of blood surrounding a dead girl's shattered skull, though. Nor the first time he'd put a pistol to a man's leg and fired, listened to the tortured screams and told himself it was the only way. The double-agent he'd exposed to save his own skin, realising far too late the man had been blackmailed. Those images were his alone. And perhaps it was reasonable to be upset about that, too, but no one had asked, and no one really knew. And if no one knew then he couldn't very well indulge in the urge to react properly to the spectres still haunting his steps. They'd all think him mad.

There were so very many memories crowded into the locked rooms of his mind palace, now. Haphazard and disorganised, tossed in without his wanting to look, they'd begun to spill out and infect everything else. He couldn't so much as hold a kitchen knife without remembering the searing pain of being stabbed in the side, the frenzied fistfight afterwards and the sickening feel of metal on bone when he'd plunged that same weapon deep into the chest of his attacker.

Had that woman died? He'd been forced to flee before finding out. Had she crumpled in the street behind him, gasping feebly whilst her blood drained into the gutter, alone and terrified?

John's wedding: three cigs.

Fifteen minutes' walk would bring him close enough to a main road for a cab to pull up without the headlights being visible back at the reception. There wasn't any hurry to get there, though, so he drifted along through the dusk like a wandering spirit. The dwindling ember at his mouth was his own personal will-o'-the-wisp, bobbing on ahead of him to light the way.

Alone like this it was easy to abandon self-awareness. He could almost forget who he was. Dismiss all notion of the world with its rules and social expectations and just... exist. Free of personal ties.

The nicotine had long since dimmed the distracting ache of thoughts and memories, and with no faces in the darkness to remind him of his status as a human being Sherlock let himself pretend. He was nothing but a ghost, then - the disconnected soul of a dead man. Perhaps even a shade of the man who'd done all those awful things, the one who'd seen blood and squalor and death and survived his own suicide. That man's ghost would be a vengeful, malevolent poltergeist, he decided. Chucking furniture about just to hear the din. Not a pleasant haunting at all.

But he didn't have to go that route. Could just as easily be a nameless apparition if he liked. A soul unfettered by the memory of flesh. No life had ever ticked by tracked by packs of cigarettes, no friends ever punched him square in the jaw for failing to remain dead. His only companion was a flickering orange spot of faerie fire guiding him faithfully along through the fog.

A sudden streak of movement overhead caught his attention and he stopped to look up, spotting the tail end of a shooting star. Some silly part of him suggested he make a wish, but he couldn't think of anything he wanted so instead he just stood and watched the slow dance of the heavens for a few silent moments.

As he stared into the distant sky the warm glow of his dwindling cigarette finally winked out. Without thought he lit another one.

His will-o'-the-wisp flickered back to life, ready to weave him a new path through the aether.

John's wedding... four cigs.