A/N: For any interested parties, the song he plays here is called Violin Sonata in G Minor by Tartini, more commonly known as the Devil's Trill Sonata. I've always found this to be one of the most seductive songs I know. I don't listen to it when I drive. Also, I was invited to a Bible study group while writing this. Just think about the irony there for a second.

John rolled over and glanced blearily at the glowing red digits on his bedside table. 3:47. Dear God, what had he done to deserve this. He groaned and placed the pillow over his face hoping it might dampen the noise. Even if it didn't, he mused, there was still the added bonus that suffocation would at least bring him some relief.

SCREEECH screech screech SCREEEEEEECH.

Sweet lord, death could not come quickly enough.

John gave a frustrated growl as he threw off the pillow and duvet, resigned to the fact that there would be no more sleep that night…this morning. Hell. He struggled into his pyjama bottoms and down the stairs.

The scene downstairs was exactly as he had imagined: Sherlock stretched out languidly on the sofa, fingers sure on the strings despite the seemingly random procession of notes. He didn't even open his eyes when John walked into the room.

"She used a different detergent," he mumbled as though it explained everything. In his mind it probably did.

"Of course," John said, running a weary hand over his face and groaned as he collapsed into what had, in the course of a few short months, become his chair.

Sherlock opened his eyes at the sound, his gaze focused on the doctor for an unnerving moment before closing them. "You look tired."

"Yes, well I've been finding it a bit hard to sleep with all the racket."

"I told you I play the violin when I'm thinking, and you –."

John cut him off. "Yes, but I'd assumed you meant playing real music."

One condescending eyebrow crept up. "Real music?"

"Yes. You know, something with a discernible tune would be nice every now and then."

Sherlock scoffed dismissively. "Boring."

"Boring?"

"What you call 'real music' is simply a study in predictability. Fantasy in the banal. Exercise in the key of mediocrity."

"What are you going on about?"

"Your 'music'," he snapped tetchily. "There's no spontaneity, no spirit, no mystery. Every note is so contrived and painfully predictable. What's the point, where's the genius and the joy in creation and composition if anyone with a half-trained ear can know the end before you've even begun."

"And what's the point of having a Stradivarius if you never use it to play the music it was made for?" Sherlock gave him a mutinous look as he tightened his possessive hold on the instrument's neck. John sighed and levered himself out of the chair. "Nevermind. Play what you want, I'll just go stuff my ears with cotton and try to smother myself with a pillow. Again."

He had almost made it to the stairs when Sherlock began to play a few gentle notes in a minor key. The melody shimmered in the air, barely louder than a hum, a light trill enticing him to turn around, come back. John did, slowly to find his flatmate staring intently at him breathing in time to the music. A quick forte, a slight quirk of the lips, and an equally swift decrescendo read like an apology, an invitation.

I'm sorry. Please, come back, sit down. Let me play for you. Let me play with you.

He did so, eyes never leaving the grey ones in front of him as he sat mesmerized, watching Sherlock's body sway slightly with the music, unaware of his own moving in response. His breathing and the tic of the clock seemed unnaturally loud as the first movement of whatever this was drew to an unassuming close.

They sat in silence for a few moments until Sherlock lifted his bow again. John was sure he saw a challenge there as the first salvo rang out, but what sort of challenge he was afraid to guess. He tore his eyes away from that transfixing gaze, trying to find a safer place to look, soon finding himself entranced by Sherlock's quick fingers on the strings. Oh, perhaps this wasn't safer. They showed all the surety they had before, but rather than moving randomly they now danced dexterously up and down the slender neck of the violin, drawing out crisp, delicate trills. The contrast between pale hands and dark wood was thrilling. He felt his pulse begin to race in time with the music, crossing his legs uncomfortably in his seat; never had he reacted so viscerally to a piece of music before. Music was just music, but now he was having difficulty separating that swirling melody from the eyes boring into his, the lean body and confident hands attached to that beautiful instrument. Perhaps he could just get up and leave. His jumper was long enough; it might still be able to preserve his dignity.

But the melody changed again, and John couldn't bring himself to go. Suddenly it was quiet and soft again. Slower, but not hesitant. Sensual, almost like a lover's reassuring caress.

No, don't go. It's alright. You'll enjoy this, I promise. There, see? Just stay with me.

John knew these were not safe thoughts to be having right now, but felt himself relaxing back into his chair as his heart began to slow again, eyes closing against the scene before him, missing the mischievous smirk before the music suddenly launched into a seductive staccato. His body tensed, eyes snapping to Sherlock's without conscious thought. His breathing once again sped up in time to the quickly climbing harmonies, and how was it that one man could control his body so completely with a simple piece of music? He could see those talented white hands again. They would contrast so nicely with his own tan skin; play so skillfully on his body. He desperately tried to conceal the growing discomfort in his trousers, but he knew there was no point. Sherlock's grin was almost predatory as his eyes raked down his body. The frenetic trills resolved into the reassuring purr of the legato, but John refused to be lulled into security again, as it quickly transformed into another dizzying slurry of notes.

His body remained taught as the legato came again, but instead of reassuring it now seemed darker, more like a challenge or a seduction before it flowed back into the playful and almost dangerous staccato. As the music became more frantic, John could no longer hide the slight tremor running through his body. Obviously looking at Sherlock's hands was not the solution, nor was looking at his lips, wet and slightly parted. He closed his eyes and tried to rally his self-control. Certainly this was his most dangerous mistake as when he opened his eyes Sherlock had moved to the chair across from him, eyes dark, breathing fast, fingers moving almost impossibly over the strings.

John's desperate swallow did not go unnoticed as Sherlock launched into the ridiculously complex, almost disjointed cadenza. God he was so close, and his scent and the sound of his heart and the violin in his hands were getting jumbled with eyes darkened with passion and hands almost a blur on the strings. He couldn't help himself as he felt his body tensing in time to the almost discordant and alarming spikes in pitch, eyes closed and mouth slightly opened. The piece came to an alarming stop as the music suddenly stopped. John gasped, breathing out a plea for forgiveness or relief he wasn't sure.

He opened his eyes to see Sherlock staring at him. His hair was mussed from lying on the sofa, his pyjama bottoms hanging off his slim hips, his breathing slightly elevated from playing, eyes wild and dilated, and God he already looked thoroughly debauched, and he could only think that this was most decidedly not helping before Sherlock lurched forward and captured his lips in a clumsy but demanding kiss. His groan was quickly swallowed by his flatmate's mouth as he felt those talented fingers slip underneath his jumper, and oh he could feel the calluses on the tips of his fingers as they played out notes on his body now, and it should have been weird but it wasn't and they should at least put the Strad away and…oh.

"You can't tell me that that was a study in mediocrity," John breathed. They lay tangled up in the sheets on John's bed as he quite frankly didn't want to know the experiments Sherlock conducted in his own room.

Sherlock's fingers played out an absentminded melody in three quarter time on his partner's chest as smirked into John's shoulder. "No, but I did have a pretty good idea of how it was going to end."