Disclaimer: Sherlock isn't mine.

Firstly I just want to say that this is my first attempt at anything M rated in a very long time. I was so, so, so nervous and worried about posting this, also. :S I hope it's ok and I hope you guys enjoy it.

As promised and as you probably read in the summary, this goes out to anyone who read my other fic The Hangover and was disappointed by the fact John and Sherlock didn't get together in that. Hope this little one-shot makes up for it. :) Reviews are love.

Desire.

John had been drinking. Slouched back on the sofa, he looked up at Sherlock's approaching footsteps and groaned. The taller man regarded him curiously.

"Do try to not be sick on the carpet. Mrs Hudson will raise our rent again."

John grunted a reply, not entirely sure whether he was agreeing or disagreeing. His mind had wandered away from anything logical and straightforward the moment Sherlock entered the room. Through the haze of alcohol induced slumber, the only clear emotion and motive was desire.

Desire for Sherlock.

"Sherlock..." John knew he moaned the name in a totally inappropriate sensual way, but couldn't find the strength to care. With a grunt, the doctor lifted himself up slightly. Blinking, he brought Sherlock into focus. "I need you to do an experiment."

Despite being wary and slightly worried, Sherlock couldn't stop his eyes brightening at the suggestion. He'd been bored. No cases. No murder. No investigations. No experiments. Nothing. He needed this.

"What kind of experiment John?"

"Me," John slurred. "I'm the experiment."

Sherlock frowned. "What?"

"Take experimenting to the next level, Sherlock. Take me."

And the proposition was made like that.

John with his desire for Sherlock and Sherlock with his desire for experimenting. At least that was how it had begun.

"John, are you sure?" Concerned.

"Yes." Husky.

"You know I'm... incapable of love. Incapable of emotions and relationships. Incapable of what you want from me."

"I know." And John did know. But his heightened desire could not be lessened by that momentary sadness. Sherlock nodded and slowly stepped towards John and the sofa, observing everything in front of him.

John's pupils had dilated, widening with uncontrollable lust. Sherlock ran his eyes over John, taking him in. The thin lips, parted softly to allow his breath to come out in tiny, short pants. The ruffled hair, all messed up. The checked shirt, tight across his chest as he leaned against the sofa. And the tight jeans, already straining at the groin.

"Sherlock..." It came out a croak.

Quickly, Sherlock striped his jacket, throwing it on the back of a chair. Bare feet padding the carpet as he moved towards John, stopping only a foot away. And Sherlock's mind went into hyper-drive.

He wanted to take this slowly. He knew he should take this slowly. Slowly was logical. John was drunk, he shouldn't be doing this. Experiment or not. Taking advantage was wrong. So wrong...

Sherlock dipped his head as John lifted his and their lips met. Softly at first, as they tested each other.

Sherlock felt as though his world had exploded. Though physically impossible, electricity clearly sparked between them. John groaned and it took less than a micro second for Sherlock to involuntarily deepen the kiss. He ran his tongue along John's lips, gently tasting before plunging it deep into his mouth. John moaned again, reaching up to run his hands through Sherlock's hair. And, gently as though it were the most natural thing in the world, Sherlock's hand fell down, settling on John's hips.

Seconds passed. Then minutes. Then hours. Then a lifetime.

Time lost meaning and it was only when Sherlock forced himself to pull back did he realise. Red and swollen, John's lips were pulled into a pout. And Sherlock's heart stopped as though he'd just made the greatest discovery of all time. Something stirred deep within him. A boiling mess, frothing to the surface and threatening to spill over. It settled back in the pit of his stomach and Sherlock let out an automatic groan. He didn't fully understand, but he didn't need to. It felt too good. He wanted more.

Because this was desire. True desire that was nothing like his desire for work or for experimenting. It was suddenly a desire for John. And his addictive personality wouldn't say no.

Pushing the shorter man, back onto the sofa, Sherlock straddled him. Lips crushed and hips ground together. Sherlock felt like he would burst; the pressure was almost unbearable. Cool hands suddenly slipped beneath his purple dress shirt and he hissed in pleasurable agreement.

The shirt was discarded; thrown away a moment later. John trailed kisses across his jaw line and down his neck, stopping only when he reached a nipple. He paused to suckle, to nip and to flick his tongue across the taunt peak. Sherlock's eyes fluttered close; never had he been so glad about John being a doctor. Moments later and John's lips were once again smashing into Sherlock's. With groins still grinding and bucking together, they both knew what came next. "Pants..." Sherlock can't remember if he groaned the word or if it was John. But soon, the remainder of their offending clothes had disappeared.

And then they were unsure.

Naked, Sherlock straddled John again. Their erections bobbed between them, overly swollen with desire to be released. The phrase "pork sword fighting" sprung into John's mind and he started to giggle. And then he stopped. A hand, warm and gentle with impossibly long fingers wrapped around his cock.

John's mouth opened in a soundless gasp. Sherlock began slowly pumping. Up. Down. Up. Down. He stopped and a thumb brushed the tip, smearing pre-cum over the head. John bit his lip so hard it nearly drew blood. Sherlock began pumping again, increasing the tempo so slowly it was antagonising. And rhythmically, John thrust into his hand, his mind blank to everything except the pleasure Sherlock currently gave him.

"Sherlock." It was a restrained whisper. "Sherlock I... I can't... God, Sherlock!" John yelled as with a final thrust he came. Sherlock responded by pressing their lips together. He trailed wet hands up and over John's shoulders, caressing down his back, before coming to rest at his backside. Squeezing the cheeks, Sherlock used the leverage to bring their groins together again, trusting into John's navel.

He still ached with unreleased desire.

"John, I need you John."

John hushed him and then, with unexpected strength, he switched their positions. Gently he pushed Sherlock back into the sofa and spreading the detective's legs he marvelled at the sight before him.

"John!"

Sherlock hissed again as John lightly stoked cool fingertips up and down his length. His desire for this had built impossibly quickly out of nowhere. As John began returning the favour, Sherlock found he could no longer think. His mind was a haze, blanked out in white hot passion. The tempo increased only slightly, but it was enough. Enough to tip Sherlock over the edge and come.

John's name was on his lips as he did.

~ *XX* ~

Sherlock woke first the next morning, with a heavy pressure on his heart. John was curled up beside him, breathing softly. His arm was draped across Sherlock's chest, explaining the pressure.

At first he wondered why he felt so confused, but then the memories from the previous night returned. In minds eye, Sherlock watched how it had unfolded as though he had been spectating, not participating. He didn't understand. The desire had gone now. How could feelings and emotions be so fleeting? Were they always like this? Did they always make one feel so empty and cold?

"Morning," the faintest smell of alcohol was still on John's breath as he spoke. It made Sherlock cringe with unbearable guilt and feel almost dirty. He shuddered slightly as the stale alcohol tickled his nose. He'd never woken up so close to someone else before.

Sherlock didn't reply. Suppressing a groan and the sick feeling he suddenly had, he extracted himself from John and from the couch. And ignoring as John called his name, he left the room, hurrying to his own shower and locking himself in.

Leaning against the wall, Sherlock let out a shuddering sigh. Never had he felt so confused before. The memories from last night flashed before him and with a sudden weakness, Sherlock slide down the wall, curling into himself when he hit the floor. Everything about last night had felt right to him. Even, John, under all his intoxication, must have felt how right it had been. But now, in the harsh light of day, everything seemed wrong. Everything Sherlock had felt last night had diminished into nearly nothingness. He just couldn't understand how he could feel so strong about something and then hardly at all just a few hours later.

Never had he felt like this before. Never had he had emotions and feelings like this before. He had been wrong when he'd told John he was incapable of such things.

There was a knock at the door and John's muffled voice. Sherlock ignored both and ran himself a hot shower.

He stood there, in the hot stream until the water ran cold.

John was dressed in a striped jumper and holding a cup of tea when Sherlock re-entered the room.

"You remember, don't you," Sherlock said before John could speak. He felt the guilt overcome him again. "I'm sorry."

"What? Why?" John had obviously pushed the foggy hangover away and he frowned, placing his mug down.

"I took advantage."

"No. I forced it onto you." John took a step closer to Sherlock.

"I... I wanted it."

"So did I."

They paused, simply staring at each other. John had always found Sherlock's steely gaze disconcerting, but now he found it beautiful.

"You're beautiful," it was a hushed whisper. They were standing so close that John's breath wisped across Sherlock's face again. But the detective wasn't listening fully. He knew what he had to admit now.

"I was wrong," he said.

"About?"

"Myself. I'm not incapable of emotions and love. I feel so many things, I just..."

"Sherlock?" Soft.

"I just don't understand them. It's so fleeting. The desire, it was so fleeting and I wanted to... I just... I feel things now, that I didn't last night and I feel..." Sherlock trailed off, upset. He was smart. So why didn't he understand this. It didn't make sense.

But John was smiling slightly. "Sherlock." And he took Sherlock's hand in his, giving it a loving squeeze. "Sherlock, I can help you understand."