So yeah, true story: I was actually getting some work done tonight, but someone linked to Kinkajou's delicious NSFW Sherlock gif on Tumblr (a-kinkajou dot tumblr dot com/post/113305256158/30-days-otp-challenge-nsfw-version-day-4) and I got a little distracted. And then I wrote some porn. And now I have porn but no progress on my real book and it's 1 AM and I'm not the least bit sorry.

John would be furious if he knew. Probably. Well, at least 78% certain. Sherlock kept the box of pictures very well hidden, on the top shelf of his bedroom closet where he knew John couldn't reach without dragging in a chair from the kitchen, and why would he do that anyway? In a perverse way, the picture kept Sherlock from ever being too tempted by cocaine again. Because if he relapsed, John would storm around the flat and uproot everything that was Sherlock's, looking for a hidden stash, and then he'd find the box and he'd go all angry and silent and dangerous and then he'd leave, probably for good. Better to hide it and stay clean.

Sherlock double-checked that his bedroom door was locked (silly habit, John was at the clinic all day, but it still felt safer with an extra barrier between him and the front door) and pulled down the small box. Five pictures, all nicked from the collection of four-by-sixes in the shoebox at the bottom of John's footlocker. John never went back through his souvenirs from his time in the army, but he liked keeping them close. Safely locked away. (Like a simple mechanism like that could deter Sherlock.) These five were the best of the lot - John in his fatigues, smiling cheerfully at the camera. Group shot of John and his squadmates. Another solo photo of John, serious now, gun and gear slung over his back like he was about to head out on a patrol. Probably had been, when the picture was taken. A fourth of John and his friend Bill, shoulder-to-shoulder, mugging for the photographer in what looked to be a third-rate bar somewhere off-base. And the fifth . . . Sherlock traced his finger over it. John shirtless, dog tags dangling from his neck, camouflage pants belted loosely around his waist. With the best fuck-me expression Sherlock had ever seen. Female photographer, then - someone he'd been flirting with. Someone Sherlock would never be able to deduce.

The only other item in the box were the pants. Fire-engine red with white trim. They had been John's, too, and Sherlock never wore them except for times like this. When he was so desperate for something that he couldn't stand it any longer. He stripped, efficiently and quickly, and pulled on the pants. They didn't smell like John anymore - hadn't really to begin with, since Sherlock stole them while they were clean and hidden at the back of John's drawer - but he liked to imagine they did. Imagine they were full of John's sweat and maybe a bit of precome and all those wonderful chemicals that made up John were now cradling his own hips, his cock, his bollocks. Sherlock reached down and adjusted himself through the fabric.

Right. Best make this quick. Not that it ever lasted long, once he got to this point - Sherlock was always too preoccupied with discovery to let himself tarry. He knelt on the hardwood floor, pulled the pants down to his ankles. Out of the way of any mess, since he couldn't exactly throw them in the laundry for John to see and wonder about later. Sherlock's cock was already nearly erect, just from thinking about it, just from flipping through the photos. He pulled one out, the one of John smiling at the camera, and propped it up against the baseboard of the wall. Left the others scattered around on the floor behind him, amid the military and fitness periodicals he'd bought "for John" once upon a time and then reappropriated to stick under his bed. (No need to hide those, not as closely - John wouldn't realize what they were really for, not unless he already had his suspicions. And Sherlock was very careful to not give anything away and frighten his not-gay flatmate.) They were good, full of gorgeous muscled men in uniform doing stretches and advertising combat boots and workout programs, but it wasn't the same without John.

John, who was smiling at him out of the photograph in front of him. Sherlock fisted his erection with a single lazy stroke, smearing the hand cream (less suspicious than lube to have on his bedside table - John already thought he was a bit poncy with his personal care products - but nearly as effective) down the length of his shaft, then tightened his grip and started stroking in earnest. The red pants restricted his ankles, kept his feet together at an unnatural angle as he knelt facing the wall, but that was good. He could pretend it was John telling him to stay put, to be a good boy. Sherlock imagined it was him putting that smile on John's face - maybe as John laid back on the bed and watched him pull himself off, watched him breathing more heavily and breaking into a light sweat as he worked his cock with just the right amount of pressure.

And maybe that wouldn't be enough for him. In Sherlock's mind, John was pushing himself to his feet, clomping over to stand in front of him - because of course John was in his fatigues and combat boots, he always was in these fantasies - and reaching down to draw Sherlock's face up with a single fingertip under his chin. He was smiling gently, approvingly, even as he unfastened his zip and pulled himself out. He'd be just the right length to fit in Sherlock's mouth - not porn-star huge, nothing like that, but pleasantly filling all the way to the back of Sherlock's throat as Sherlock swallowed him down. He'd dig his fingers into Sherlock's hair and lean back against the wall, maybe. Still smiling, but murmuring little words of encouragement as he nudged forward with little jolts of his hips. And Sherlock would take it, would let John fuck his face as long as he wanted, would revel in the way those blunt fingers gripped his hair and twisted and pulled.

Sherlock threw his arm up against the wall and braced himself as he picked up the tempo. John would be getting a bit more violent, now, that edge of command in his voice as he told Sherlock exactly what to do. Deeper, use your cheeks, that's it, now just tongue the slit. The imaginary voice sliced through Sherlock's brain, firing all his synapses at once. What would it be like if John turned that military-sharp focus all on him like that? Sherlock let his eyelids slip partway down, but he refused to close them entirely - that would block out the picture of John. John, so happy, so satisfied. John, who wouldn't hesitate to give orders, would tell Sherlock exactly what he was supposed to do . . .

Christ. That was it, the shove that tipped Sherlock over the edge. He seized up and came with a single, soft groan. John. Eventually he sat back on his heels, surveyed the mess - his hand, the wall, the floor. Nothing on the pants, nothing on the pictures. Good.

When John got home two hours later, Sherlock was safely sprawled on the sofa, his apathetic mask once again firmly in place. Sherlock didn't react, even when John huffed at him and pulled himself up military-straight to give him the stink-eye.

"Have you moved off that bloody couch even once today, Sherlock?"

Sherlock sighed with as much drama as he could muster. "Bored," he said.

"Yeah, thought not." John's lips twitched, just barely, small enough that no one other than Sherlock would have noticed. "Tea?"