Notes: The result of yet another prompt on the Sherlock kink_meme.

The Man who Sold the World - because linking David Bowie is never gratuitous. Though the same can't be said for that Ziggy Stardust image they pasted to that video. Just...listen, don't look.

Chapter 1

An impact like a full-body fist. The first air-splitting crack before deafness drowned the full thunder of the explosion.

Bomb.

Sherlock.

Sherlock. Bomb.

Clawing his way up from the dark, John knew he was in flashback even before consciousness registered. Male sweat and desert dust and a thousand miles of ancient resin-laced wind washed the angry stab of chlorine from his sinuses. The heavy canvas cot supporting his body, the smooth weave of his fatigues pressing into his skin, were such bright points of sensation that it seemed only natural to find his old barracks when he opened his eyes.

But it was all wrong. He'd just been in an explosion. With Sherlock. In London. He did not have time to hallucinate. No one was coming to help them; he needed to find his flatmate and get them the hell out of the building before everything caved in on them. Machine oil and the endless white dust (cement dust) coated his tongue in a bitter paste. He tried to concentrate on that, grasping for the flavour of ruined building and semtex beneath the illusion to pull himself out of this.

Ignore the men milling around the barracks. Ignore the laughter and hum of camaraderie. Ignore the bleached brightness of the Afghani sun.

He flinched back as fingers snapped in front of his face. "Hey, Doc, you in there?" Bill Murray leaned down, brown eyes crinkled with laughter. "You sleep at all last night? Christ, even I threw it in around 3 am."

The man sitting on the next cot over snorted. Dick Caville, John's short-circuiting mind supplied. Died a month before they shipped you home. "Watson was on that poor fuck who found the IED till the sky turned light. Doing surgery on 36 hours no sleep and even the Colonel couldn't chase him off. You saved that bastard's life, Johnny, and no mistake."

John smiled distractedly at him. Saving a life was always good, even if it was heading the wrong way from reality. No, no, goddammit, he could feel himself sliding into overload. Get a grip, Watson! Not. Real. "Um. Could you guys… I need to." He made a vague motion in the direction of outside.

"Shit, yeah." Bill straightened up to give him room. Forcing himself not to hyperventilate, John squeezed past him and down the narrow aisle between the rows of beds.

He pushed aside the canvas flaps of the doorway and was slapped in the face by the familiar maze of gravelled alleys and barracks tents. A few lounging soldiers glanced up at him, startled by the look on his face, but they were experienced enough to recognize a personal freak-out when they saw one. He'd thought it would end at the entrance. Step outside back into reality. But there was more white dust, more army smell, more…

He broke into a run, gravel clattering beneath his boots, till he got out to a wider lane between structures. Camp Bastion. Helmand Province. February 19, 2007. He remembered the surgery Dick and Bill had mentioned. Colonel Burroughs had given John's surgical team 24 hours downtime as a reward for nearly killing themselves putting a platoon back together after they'd been pulled out of an ambush.

But you don't flash back to the day after the trauma. For that matter, he hadn't found it traumatic in the first place. Gruelling, yes, but he'd never revisited this in dreams, let alone in 3D surround sound.

He walked over to one of the huge shipping containers that lay sprawled everywhere around the base, pulled back and punched it.

Ow.

Alright, that was real. He looked down at his hands. Steady as bedrock. It occurred to him abruptly that his shoulder didn't hurt. Not even the vague background awareness that it could hurt if he pushed it, which had been there ever since it had healed.

Adrenaline? He queried his system. Panicking heart rate, respiration rate just shy of hyperventilation, razor clarity of perception, hyperawareness. Adrenaline and then some. But it was from confusion-fuelled fear; nothing like the consuming surge of a PTSD episode.

Bill came crunching up behind him as John was licking the abrasions he'd just put on his knuckles. "John? You okay? You looked like you were losing it."

"Bill?" John turned around to face him, hating how small his voice sounded. "How do you know if you're dreaming?"