Written for trashyfiction in Tumblr's Johnlock Gift Exchange 2012. Prompt was "BAMF!John learns to deduce Sherlock". I did deviate a little I guess- learning to deduce as a whole rather than exclusively Sherlock.

This is also the first time I've written anything above Teen rating. Porn really isn't an experienced topic for me. So 'trashyfiction', take pleasure in the fact that you have just taken my slash writing virginity.

Anyway, I hope you like it, whether it was intended for you or you've stumbled across it.

WARNING: NSFW/MATURE RATED CONTENT. YOU HAVE BEEN WARNED.

"You know, that never gets less amazing." John said finally, breaking the silence as they sat in the back of the taxi headed back to Baker Street.

Sherlock smiled at the compliment. "I'm glad you appreciate my efforts."

If he let himself be honest, John far more than appreciated Sherlock's deductions. When the man unravelled crime scenes he was lost in his element, practically dancing to the grave melody of his own voice. Sherlock's mind could spill forth so many facts and observations at once that it was often difficult for those listening to keep up.

But what bothered John the most was that Sherlock was more than happy to read into other people's secrets so easily yet refused to share his own with the one person he had ever let closely into his life. After two years of living in the same flat and practically spending every waking moment with each other, John knew little more about Sherlock Holmes than he did that morning in the lab at St Bart's where they first met.

John turned to watch Sherlock gaze out of the taxi window. He studied his hands, his clothes, his hair- looking for any indication of something that he didn't already know.

"Is there a reason you're staring at me?"

John snapped out of the momentary trance he had slipped into, his eyes shooting up to meet Sherlock's before turning away abruptly. His cheeks flushed with embarrassment and Sherlock huffed amusedly.

"If you're going to ogle, John, you could at least be more subtle about it."

"Shut up."

The pair was sat in Speedy's when John finally plucked up his courage. The café is never busy and that day was no exception- a pair of old men sat together by the window and the young waitress cleaning a table by the counter. Sherlock had reluctantly agreed to get some lunch and they'd sat at their usual place by the menu board. The remnants of John's bacon sandwich had been pushed aside so he could rest his hands on the table and quickly survey the few other people there. Sherlock had been texting for the majority of their stay, pausing only to take a sip occasionally from his black coffee.

John cleared his throat to attract Sherlock's attention. The detective glanced up at him.

"Can I show you something?" John asked, smiling confidently.

Sherlock nodded silently, and followed John's gaze as he pointed to the men by the window.

"The one on the left is a war veteran, served in Africa during the Second World War. The medals are obviously a dead giveaway, but I can go deeper. You can tell because his skin is tanned like mine, and it's faded with time but not as much as it would if the colouration was caused by a brief holiday. That suggests a longer period abroad. But what if he'd just lived nearer the Equator for a while?" John paused to change his position, and a grin was spreading across his face as he continued.

"Well, he probably would have been a young man in the 40's so he would be eligible to serve. There are small scars dotted along his cheeks- possible shrapnel wounds- and a larger scar on his jaw just behind his ear which you can see now his hairline has receded significantly. He wears that hat because he's still conscious about it, and upset about its cause, so maybe it's an injury with particularly unhappy memories attached to it. The loss of comrades, an accident that may have been his fault… I've seen it enough times in my own experience to know that there are a couple of unpleasant possibilities. So, an ex-soldier scarred both physically and mentally by fighting in a world war, and I guessed all of that just from looking at him."

He looked back to Sherlock expectantly, who continued to stare at the old man for a few seconds before unlocking his phone and continuing to tap the screen nonchalantly.

"Not bad," Sherlock said, "but not overly impressive."

John sat completely still. He had hoped for more enthusiasm, or at least recognition that he'd managed to deduce a man's history just from looking at him. But Sherlock continued to stare at his phone with an unemotional mask, his eyes flickering occasionally to browse whatever he was scrolling through.

"Fine." John huffed, standing as he forced his chair backwards. It screeched against the floor which made everyone present wince and turn to the source of the sound. John blushed despite the firm frown on his face and stormed out of the café.

Sherlock glanced at him before following, barely making it through the door as it swung shut behind John. It wasn't hard to catch up with the smaller man, and Sherlock was soon striding alongside him.

"John, I apologise."

"Fuck off."

"You must understand that I'm not being rude. You were right- which was rather clever for an average person, I must admit- but it wasn't much of a challenge to work out."

John stopped at the stairs to the familiar black door of 221B. Sherlock faced him and gave him a small smile.

"It was good, John." Sherlock explained, "But not 'amazing' as you would put it."

John shook his head and hurried up the stairs, digging through his pockets to find his keys. Sherlock had the sense to stay behind him and not try to broach the subject further, instead following John silently through the door and up the stairs.

Eight o'clock, John mused, wonder what's on the telly.

Sherlock had left at least an hour and a half ago, without any explanation of what he was doing or why. Not that John cared anyway.

Let him get shot or stabbed or kidnapped. Stuck-up bastard.

He changed the channel from sitcoms to music charts, not really wanting to watch any of them. Eventually John gave up, switching the TV off and heaving himself out of his armchair with a yawn. It was getting late and he felt like some tea would keep him awake, at least until Sherlock got back. He may not be on the best of terms with his flatmate at the moment, but who knew what state Sherlock might come back in. It wouldn't be the first time John had patched him up from cuts and bruises.

He trudged over to the kitchen and had just flicked on the kettle when the door downstairs quietly shut, and footsteps sped up the stairs. Sherlock spun into the kitchen and removed his coat with a casual flourish, seeming not to notice John's presence. He hung it on the back of the nearest chair and followed suit with his scarf. John cleared his throat. "Evening."

Sherlock glanced up at him, as if noticing he was there for the first time. "Ah. Good evening, John."

There was a tense moment of silence, with the two men staring at each other for a minute. John stepped forward first.

"Listen, about earlier-" he began.

But Sherlock cut him off. "I'm sorry, John. It was wrong of me to brush you off as easily as that." he took a step towards John, "It was clever, which I told you. Not quite to my level of skill, admittedly, but nonetheless it was-"

"You got the Underground home." John announced.

Sherlock paused mid-sentence, and gave John a curious smile. "Go on." he encouraged.

"This is a test." John continued, starting to grin as everything slotted into place, "You never get the Underground if you don't have to, but you're in a perfectly good mood, so you had no reason to take it. But you smell like the Underground. Like damp, cigarettes and fast food." Sherlock grimaced at this observation, but John ignored it, "The bottom of your trousers are wet, so you've been running through puddles after someone, most likely. You didn't mention anything before you left so it couldn't have been more than a 6, otherwise you would have wanted me to come with you. I'm going to guess at a small time drug dealer?"

Sherlock nodded, and John continued. "You caught him, again made obvious by your good mood. As you came through the front door and closed it, you did so carefully rather than slamming it like you usually do. You were testing me, just to see if I'd notice on that one, weren't you?"

Sherlock laughed. "Guilty."

John relaxed. He wandered back to the kettle and took out two mugs, placing a tea bag in one and a few coffee granules in the other. Suddenly there was warm breath on his neck, and he spun around to meet Sherlock face-to-face.

"What the hell are you-"

"You were worried about me." Sherlock purred, staring down at John, "You're tired, that much is obvious, but you didn't want to go to bed until you knew I was home safe."

John tried to back away, but ended up against the worktop without anywhere else together. Sherlock smirked menacingly, reaching out to John's waist slowly.

"I'm impressed, John. You've learnt a lot."

John slapped Sherlock's hand away and pushed him back, hard enough to force him without knocking him over. "What do you think you're doing?!" he shouted, "That was out of order, Sherlock!"

John marched out of the kitchen, heading for the stairs to his room, but Sherlock was hot on his heels. As they reached the foot of the stairs, John spun around and punched Sherlock, stepping towards him as he toppled to the floor.

"I don't know what's going on here, Sherlock, but if you don't snap out of it this instant then I swear to God-"

But before he could finish his threat, Sherlock grabbed John's outstretched fist and dragged him down to the floor. John was too shocked to react, and Sherlock straddled his hips and leant dangerously close to his face.

Are Sherlock's pupils dilating? He's not high or anything, is he? No, there's no other obvious symptoms, so what… Oh god. Shit.

Just as John's thoughts snapped into focus, Sherlock had fallen forward and kissed him.

The first was experimental, taking John's shocked mouth inside his own and sucking on his lips gently. John did nothing to either protest or react, so Sherlock repeated, this time thrusting just a little with his hips. That second of friction brought John straight back into the moment.

"Get off!" John demanded, gripping Sherlock's arms and trying to push him away. But Sherlock was stronger than John had expected, and barely budged at all. He against John, and a growl rose from his throat. John's vision went blank, and it seemed that every drop of blood in his body had suddenly rushed down to his cock.

Sherlock was kissing him again, forcing his tongue in John's mouth to taste every inch of the hot warmth inside. John gave up trying to struggle free and thrust his tongue forward, fighting Sherlock's for dominance of the kiss.

If this is what you want, then fine. I'm not intending to disappoint.

John bucked up against Sherlock this time, humming loudly as Sherlock shivered.

"We are not about to do this on the floor." John ordered. He pushed upwards, forcing them both to stand. Sherlock took his wrist in a painful grip and crushed their lips together, his thin arms enveloping John's shoulders. They tumbled onto the sofa, John on top of Sherlock as he fought with the fly on his tailored trousers.

"Bit eager, aren't we, John?" Sherlock teased, biting John's lip.

"Shut the fuck up."

His fingers slipped- sometimes by accident, otherwise on purpose- but before long Sherlock's boxers were in full view as his trousers slipped to the floor, tented by the strain of his erection. The slightest patch of precome had already seeped through. John glanced down at it and bit his lip.

"So, 'Three Continents Watson'. Care to show me what you've got?"

John gripped Sherlock's shoulders and bit his neck hard, making Sherlock cry out in pain. John kissed the bite mark lightly and left a trail of faint teeth marks down Sherlock's neck to just above his collarbone.

"Shirt." John huffed, "Off, now."

Sherlock did as he was told, prising open each button with a deliberate slowness before shrugging the shirt off. John ran his hands along Sherlock's naked sides, taking in the pale sweaty skin and the faint outline of abdominal muscles. "Jesus. You're fucking gorgeous."

Sherlock laughed. "It's not the first time I've been told."

John nudged his knee upwards, straight into Sherlock's groin. It had intended to hurt him, but was instead more of a rub that made Sherlock's head spin. "Please, John." He gasped.

John grinned and licked the bruise on Sherlock's face from where he had punched him.

"That's once." he teased, "Think I could manage twice?"

For the first time in his life, it took Sherlock a second to realise what John was talking about. He shot upright and gripped at John's crotch.

"You dare talk about that woman when we're caught up like this, and I'll make sure you pay for it."

John gasped at the tight fingers grasping at his cock through his jeans. He managed a strained laugh and licked Sherlock's neck from his earlobe, down his jawline to his collarbone.

"Pay for it, huh?" he said huskily, "What did you have in mind?"

Sherlock pushed John back so he could run his hands up and down John's body without any restrictions. The excess clothes frustrated him, and he tore away eagerly at John's jumper and shirt. The slightly tanned skin underneath was tantalisingly hot and damp with perspiration. Sherlock kissed down John's chest and over the star-like shape of his gunshot wound. He'd never had time to examine it like this, but now wasn't the moment. Sherlock forced down the urge to study every inch of John- he could save that for another time.

"What do you want me to do?" he asked, his voice laden with lust as he leant forward and kissed John. He felt John rut upwards hungrily against his hand and pressed down with his own hips, and both of them groaned in unison.

"My- trousers." John managed to stutter, "Too many- ah, layers."

Sherlock chuckled and skilfully released John's cock from his jeans and boxers in a few simple hand movements. John was obscenely hard and oozing precome. His cock was burning red, begging for attention. John moved his hand to do as such but Sherlock swatted it away, before pulling down his own pants.

"Now what?" he whispered, leaning against John and laying flush on top of him. He ground his hips against John's and had to choke down a violent howl. John's hand wriggled between their two bodies until it found Sherlock's, grasped it tightly, and then lead it back towards their cocks. He wrapped their fingers around the two straining erections, pressing them together. Just the feel of the heat against heat was enough to almost tip John over the edge.

Sherlock thrust once, slowly, and John sat up to improve their leverage. His legs were wrapped around Sherlock's waist, hugging him closer as they rocked against each other, free hands tangled in the other man's hair. Their foreheads were pressed together and eyes shut tightly. Sherlock groaned as John leant forward to nip at his lower lip.

"Jesus fucking Christ." Sherlock whined, almost sliding off the edge of the sofa with a forceful shove into John's hand, "Fuck, John. Faster. So much faster."

John did as he was told, panting against Sherlock's neck as he increased his pace. He could feel an orgasm just looming ahead, his thoughts swimming with Sherlock's musky smell and the tiny scars along his shoulders and the almost unintelligible words spilling from his mouth- names of deities that might not even exist, explicit words that the entire street could probably hear, but more than anything was the constant chanting of John's name, over and over.

"I'm close, John. So fucking close. I need you to- yes, John, harder! John! Yes yes yes- John!"

Sherlock came first with an ecstatic cry, his cum splattering across his and John's chests. The sudden lubrication meant John soon followed, Sherlock's name a choked whisper on his lips. They rode out their orgasms as one, bound in the other's arms murmuring nonsense words. As the heavy breaths and voices died down, Sherlock and John found themselves staring at each other.

John leant forward and ran his tongue along the faded bruise where he had punched Sherlock what seemed like lifetimes ago.

"That was amazing." he whispered, grinning and planting a delicate kiss on the end of Sherlock's nose. Sherlock laughed loudly and traced out random lines along John's lower back, the signs of arousal already stirring again between their legs.

"I'm glad you appreciate my efforts."