Author's Note: Another entry in the 'Geography of a Shared Life' project. Prompted by Benedict Cumberbatch's comments, long ago, about his sensitive folicles. Posted for Josie, because she couldn't wait for the real smut to arrive!

They had been lovers for nearly two months, and the hair moratorium was still in place. To John's complete frustration.

The thing about being told you can't have something is that you want it all the more.

John wanted to run his fingers through Sherlock's hair. He always had. Right from the moment they first met in the labs at Barts, it had been his greatest desire to slide clawed digits through those fabulous curls.

No Go.

Sherlock had been categorical about that. As soon as they were deep in their first clinch, and John's hand naturally began to gravitate to the place it most wanted to be, Sherlock had caught those questing fingers and held them tightly in his own.

'Not the hair,' he had breathed into John's ear.

Red rag to a bull has never been a better description. John instantly began to obsess. Maybe that was what Sherlock had intended him to do, he conjectured a few nights later, after they had made love for about the fourteenth time. They were lying on their backs, ribs heaving, skin glossy with sweat. John had turned to his detective and studied him, studied the way those gleaming locks fell in a halo on the pillow, and wondered if this was Sherlock's way of keeping him interested (as if he needed one).

Today, poor John had just about had enough.

Today, there had been a soft wind flowing down the Thames as they picked their way through the crowds on the Embankment, on the way to the latest crime scene – a grisly slaying under a pontoon on the south bank – and Sherlock's curls had ruffled softly around his face. They were too enticing. If nothing else, John had to have a reason why he couldn't touch, he decided, as he followed his lover down the slippery steps that ran from the promenade along the bank to the muddy slope below. He needed to know the story behind the curls.

Sherlock pulled off his scarf and shook out his mahogany mane before he crouched down over the body – female, Asian, fully dressed, ligature marks on wrists and ankles, throat cut so deeply the head had almost been completely severed. He concluded within seconds that the girl (for girl she was, no more than fifteen) had been murdered by a gang of people-traffickers for non-compliance with their plans, as a warning to others as much as anything.

He stood up, brushed non-existent mud off his knees and turned to John. The breeze caught the hair around his face and pressed a particularly defined ringlet against his sculpted cheek.

'Well, I think that concludes that. Shall we, John?'

John nearly swooned. In public. It was extremely embarrassing.

This could not go on, he realised as Sherlock hailed a taxi back on the roadway above the river. It was now or never.

Back at Baker Street, Sherlock bounded into the kitchen, shedding his Belstaff in a tweedy swirl, and resumed his seat at the table, where he had been going through a box of slides of diseased liver tissue when Lestrade's intriguing text about the murder came in. John shed his coat more slowly, opened the living room sashes to let in the Spring breeze (and perhaps a little courage, if he was brutally honest), and wandered over to lean on the kitchen door jam. He watched Sherlock for a while, that dark head bent over the microscope and then realised he must take the plunge.

'Sherlock, we need to talk.'

Sherlock took one glance at John, rolled his eyes and groaned.

'Oh, God, this is going to be one of those hideous relationship talks, isn't it? This is why I have always avoided intimacy, John. It's not the sex I can't stand, it's all the bloody talking about it afterwards.'

'Look, I need to know-'

'About the hair, yes, I gathered that.'

'How-'

'Because you are perpetually staring at it. Sometimes, my dear, you are palpably transparent. It's getting embarrassing. I'm sure even Anderson noticed today, and he is about as observant as the average parsnip.' Sherlock resumed his study of the slides.

'Sherlock, look at me, for God's sake! This is important!'

The detective sat back. Then he turned to John, and raised an eyebrow in a way he knew the doctor found irresistible.

'You bastard.'

'I never pretended I wasn't.' He sighed. 'So what did you want to say?'

'Why?'

'Why what?'

'Don't be obtuse, Sherlock. Why won't you let me touch it?'

'I'm sensitive,' he said.

'Sensitive? What does that mean? You have dandruff?'

Sherlock didn't laugh.

'Okay,' John growled, rolling his eyes. 'Not dandruff, then. Psoriasis? Or are you bald?'

'I think you know my body intimately enough now to have detected whether a wig, or even a partial hairpiece, is in evidence.'

'Alopecia.'

'Eyebrows,' Sherlock said, pointing at his own dark arches.

'Not alopecia totalis, obviously. But you could have bald patches at the back. Maybe you keep your hair longer to cover them up.'

'Still detectible even to an idiot like you in a breeze like today's,' Sherlock growled. 'And I have certainly not had follicular unit transplantation, which was going to be your next question, I have no doubt.'

'There's no need to be ashamed of baldness, Sherlock.'

'You only say that because you haven't got it!'

'So you are worried about baldness-'

'No I am not!' Sherlock almost shouted. 'My hair is sensitive, that's all!'

John leant against the kitchen unit and stared at Sherlock very pointedly. The detective threw up his hands in exasperation.

'Alright, alright! I have sensitive follicles! I can't bear to have my hair touched! It's bad enough to touch it myself, but to have someone else-'

'You mean it hurts?'

'Not as such. Sometimes. Mostly it's more like a kind of sensory overload. Extreme sensation. If you pulled my hair, I would be helpless, John, I really would. I can't stand it!'

John frowned. 'Like Samson. All your power lies in your hair, and-'

'I am well aware of the story of Samson, John. And it is hardly applicable in this case, since cutting off my hair has no effect on my intellectual or physical prowess.'

'But you let it grow, so-'

'I do not keep it short because I cannot abide having my hair cut any more often than is absolutely necessary. It has taken me years to find a barber capable of working within my limitations. Until I did, I had to allow it to grow untouched.'

Sherlock with a wild mane of long curls was suddenly an entrenched image in John's imagination. Sherlock recognised the instant the fantasy arrived inside John's head.

'No, absolutely not! I am not doing that again!'

'You never know, it might be nice.'

'I do know, and believe me, if you find it hard to live with me now, you have no idea how bad I would be without a proper hairdresser in train.'

John thought for a moment. And then stepped forward.

'So you let your hairdresser touch it,' he ventured.

'Yes. Grudgingly, I admit, but I do. He is gentle.'

'Don't you think I could be gentle?' John let his voice drop low and soft. He had a naughty inkling in his head now, and a smile forming on his lips.

Sherlock looked up at him, sceptical. 'Is that a trick question?'

'You know I can be gentle, Sherlock,' he cooed. 'I'm always gentle when I-'

Sherlock cleared his throat awkwardly. 'Yes, I'm well aware of that.'

John took a step closer. 'So why don't you let me try it? Just a touch?'

Another step and John was standing over Sherlock, looking down at him, less than a foot away. Close enough for the scent and heat of his body to reach the detective. Close enough for his suggestive purr to have an effect.

Sherlock blushed.

'You never know,' John breathed. 'You might like it. It might turn out to be-'

'Nice,' Sherlock whispered, and closed his eyes very, very slowly as John's fingers reached out.

It was the same curl that had brushed Sherlock's cheek earlier, by the river. John took care to disturb the root as little as possible as he lifted it gently between his fingers. It was dark and richly glossy. The shaft of each hair was very thick and wiry, the kinks deeply formed within the structure. John let the spiral lick its way around his index finger, supporting its weight as he appreciated its shiny beauty.

Sherlock made a soft noise in the back of his throat.

'Is this okay?' John asked him, and received a tiny nod in response.

John released the curl and it sprang back, jostling its neighbours. The ringlets were too tempting not to touch. He cupped them in his palm, feeling them brush and bounce softly against his skin.

Sherlock sighed.

John lifted his hand fractionally, meaning to weigh the bounce in his hand, but as he did so, he realised he was releasing the weight that pulled each strand down, allowing the curl to rebound against its root and disturb the follicle. He was about to pull his hand away, but then something extraordinary happened.

Sherlock moaned.

Actually moaned.

And John knew that sound. Knew it from seven and a half weeks of making love to Sherlock Holmes. Seven and a half weeks of kissing, caressing, stroking, tantalising, licking, sucking and fucking him. He knew exactly what that sound meant. And it had nothing whatsoever to do with pain.

He lifted his hand again, bouncing the curls against his palm, letting them massage Sherlock's sensitive scalp themselves.

'Oh, God,' Sherlock whimpered. His head fell slightly forward, forehead coming to rest against John's chest.

John took the opportunity to stroke his free hand up over the nape of Sherlock's neck, downy as it was, and into the soft ruffles at the base of his skull.

'You like that?' He whispered.

Sherlock shuddered.

John let the pads of his fingers delve gently onto Sherlock's scalp. He didn't press hard, just made tiny, delicate brushes against the skin.

'Oh, fuck!'

Sherlock grabbed his waist and tugged him down suddenly, forcing him into his lap. The instant his weight settled, he felt Sherlock's cock against his thigh, digging into the flesh. He was already fully hard.

'My God, Sherlock!' he gasped in disbelief.'

'Don't stop,' Sherlock panted, and ground up against him. 'More!'

John slid his fingers under the curls at the side of Sherlock's face, stroking through them as he had always longed to, but careful to take it slowly, so as not to tug at a tangle with painful results. At the same time, he lent down and claimed Sherlock's open, panting mouth with his own, and was rewarded with another moan. They began to kiss hungrily, devouring each other's lips, John wiggling around to straddle Sherlock's lap, and Sherlock bucking up to gain the friction he needed to complete his pleasure while John skimmed his fingers all over his scalp.

It was clear this wasn't going to take long, even fully dressed, but John grossly underestimated just how quick and how strong the climax would be. Almost before he knew what was happening, Sherlock's hips were jerking underneath him, his whole body shaking as he reached a massive and sudden orgasm.

John stroked him through it, eeking every last delicious convulsion out, not with his fingers on Sherlock's cock, as he would have expected, but by cupping the back of his head and smoothing his fingers through the thick, dense curls. Eventually Sherlock flopped forward against him, trembling and weak with pleasure.

John pressed his lips to the detective's ear and let his hot breath do half the work.

'Did it ever occur to you, my clever darling, that your unusual follicular sensitivity and my interest in head massage were made for each other?'

'Oh, God, I'm so fucked,' Sherlock groaned into John's shirt.

'Not yet, you're not. But I'm hoping to change that…'

After some more heated kissing, John lifted his head and peered down at his quivering, sex-dazed lover.

'How come Samson didn't get deleted?'

'Serial killers like Biblical themes, John,' Sherlock murmured. 'Obviously. Do try to keep up.'