Well, here we finally are, the moment of truth, when I find out if I can actually write this stuff. Please be gentle. You will find that I drop into present tense when things start hotting up. It's a deliberate strategy – I think it makes things more immediate, puts the reader directly into the scene. Let me know if you agree. Oh, and there's more to follow…

On Sunday morning, Sherlock slipped out of bed and left John sleeping. It was early and the bathroom was filled with the pearlescent haze of winter mornings. He stood in front of the mirror and examined himself. He was naked – they always slept naked these days. John said he needed to be able to reach out and touch Sherlock's skin in the night. Apparently it helped with the nightmares, though Sherlock was sceptical about this, since he didn't seem to have experienced one since they had taken up bed sharing.

Sherlock was not under any illusions about his body. Everything about him was long and thin, something he had to get used to as a teenager when his first real growth spurt had started and then just didn't seem to stop. He had become one of those people who looked like they had been stretched on the rack. He was bony too, ribs like a toast rack, hips like plough shares. All bones and salt cellars, as Nanny used to say.

And he was covered in scars. Nothing like John's of course. That kind of scar tissue came from nothing other than life-threatening trauma, something Sherlock had been lucky to escape on several occasions, most recently during the pool incident. No, Sherlock's scars were subtle, they needed to be divined rather than seen. The scars on his arms and in his groins where he had injected himself during those miserable lost years. The seam across his belly from a childhood appendectomy. Various burns and scalds from experiments gone wrong. The notch in his thigh where the Lambeth cheese-wire killer had taken a chunk out of him while resisting arrest. Now he was adding another mark to his collection.

He took a long, hot shower.

The heat and water moistened the surgical tape just enough. He piggled it off with his fingernails. It left a white deposit on his skin. Underneath, everything was well healed. Perfect, in fact. He congratulated himself as he examined it closely in the shaving mirror.

Alert as usual, he heard movement. John was up, woken by the roar of the shower, no doubt. Everything going to plan then. He opened the bathroom door just a crack to confirm his suspicion, then called out.

'John! Can you come and look at this?'

There was a brief pause, and then the doctor came in, shutting the door behind him to keep the warm fug of steam in. Sherlock had carefully positioned himself with his back to the entrance, so John would not be able to see.

'Have you taken the dressing off? Sit down so I can get a better look.'

Sherlock sat obediently down on the lid of the lavatory and stretched his neck.

He heard the breath catch in John's throat. Shaking fingers reached out and brushed his shoulder. A faint whimper. He looked up and saw tears in John's eyes.

'Oh, my love, what have you done?' He murmured.

Sherlock grasped his hips and pressed his face into the doctor's soft belly.

'For you, John. Only you.'

It was a simple thing, and a small one. It had hardly taken any time at all, and had hurt much less than Sherlock had anticipated. Certainly much less than his backside had hurt that day. He had known exactly what he wanted, so there was no problem there. It started with the simple legend that John had embossed on his leather medical case, his passport cover, and on the dusty army kitbag that skulked in the bottom of his wardrobe. Sherlock had added two more lines himself, but the effect was very pleasing, he felt. Four lines of tiny, neat lettering in a rectangular frame at the base of his neck, just to one side, where the upright of his collar would cover it, but also where just a slight movement might reveal it to a casual observer. It read:

Property of:

Dr John H Watson RAMC

Inside and Outside

Now and Forever.

Sherlock presses kisses to John's fluttering belly, nuzzling the silky flesh, tugging the sandy blonde hair with his teeth. He strokes the satin skin of his lover's loins with the tips of his fingers and then presses his nose hungrily into the nest of John's pubic hair to inhale the delicious scent of him, so male, that aroma of lust and perspiration and damp that makes his mouth water. John makes a soft noise in the base of his throat. He is getting hard, more so as Sherlock pushes his nose in, taking long lungfuls of musk. A good, solid nose can be a sexual advantage, he has discovered.

Then, when he is satisfied John is sufficiently aroused for his purpose, he lifts his head slightly and begins to nip at the base of his cock, the place where the corpora and veins meet amidst rumpled skin, the very root of John's sexual being. The place he knows turns John on the most.

The doctor lets out a moan and flops his head back.

Sherlock gnaws lightly, expertly, because he has recorded every response on every occasion and he knows, without any doubt, that this is what feeds John's desire the heat it needs to unfold into a roaring conflagration. He nibbles, runs the flats of his front teeth along the ridge, kisses, licks, and returns to nipping, oh so gently, so tantalisingly.

'Oh, God, Sherlock!'

He takes his time, letting the pressure build under his lips, until even he can resist no longer. He traces the corpora up with the flat of his tongue, rasping it over the sensitive fraenulum at the head, then lapping at the sticky fluid that has already spilled from the crown. Above him, John moans. He thrusts his solid fingers into Sherlock's curls and tugs, but Sherlock won't be hurried. He swirls his tongue around the swollen glans, then tightens its tip and presses it into the tiny slot at the top. John gasps. Then Sherlock swirls again, and caresses circles around the base of the head, where John's foreskin has rumpled up. It tastes slightly salty, and so, so good. Against his lips he can feel the throbbing of the blood as it rushes under the velvet skin. John thickens continually as Sherlock licks.

'Oh, Jesus, Sherlock, please!' He groans.

No point in denying either of them the pleasure any longer, Sherlock decides, and takes the magnificent shaft into his mouth. They both moan with the shock of the heat from it. The hard, heavy flesh resists Sherlock's teeth. He sucks gently, swirling his tongue again. He's getting so hard himself it is almost torture, sweet torture, but he isn't going to stop now because he wants John to have the biggest orgasm of his life. He's been planning this since he sat on his throbbing arse in that coffee shop in Spitalfields and now, lo, it has come to pass.

Still, that's a huge wad of meat to fit into even the biggest mouth, and Sherlock has to concentrate hard on relaxing his soft palate so his gag reflex doesn't kick in. Because now John's hips are starting to writhe and thrust. He is helpless in the face of Sherlock's onslaught. His head flops forward and his fingers tighten in the detective's hair. His other hand clutches at Sherlock's shoulder for balance. Sherlock decides to ramp things up just a little bit more. He slips a hand down and between John's legs, and the little man scoots his feet apart just slightly to accommodate him. Sherlock strokes and rolls John's balls, then probes behind them and reaches the perineum. John starts to pant. Sherlock's fingers begin a relentless caress, in tandem with a renewed sucking and the introduction of just a little tooth.

'Oh yes, yes,' the doctor moans, thrusting harder now. He is getting so tight, so hard. He can't last much longer.

Sherlock gives in. He wants it so badly, and John is thrusting so hard, virtually humping his face. He wants to take the entire length down his throat but he can't do that yet, even though he is trying, because his jaw hurts so much. So he just lets go, softens his lips and receives. And as he does, he slips his hands around to John's magnificent buttocks and digs his nails in very, very hard.

John throws back his head again and lets out a strangled cry. And everything goes deliciously liquid.

Sherlock tips his head back and lets the gorgeous fluid pump down his throat, hardly tasting it at all. He sucks the last drop out and pulls away with a gurgle and a satisfied slurp.

John is shaking. His knees give out and he collapses into Sherlock's lap, a leg either side, and hangs on, head on the taller man's shoulder, trembling and sweating, while the last convulsions die.

'Oh, Sherlock,' he sighs when it is finally over.