A/N: Sorry for the delay. It's the last week of the semester here, which means that I've written three essays in the last two weeks. I finished this while procrastinating from study for the two tests I have on Thursday. The plus side of this is that after Thursday I'm done for the year so nothing to do but update! More sex soon, I promise.

John was in the kitchen when Sherlock emerged from his bedroom, studiously cubing a chicken breast. He smiled at Sherlock when he leant past him to fill a glass from the tap. Sherlock saw his eyes flicker subtly from his face – the flush of orgasm most likely still fading from his cheeks – to his trousers, a noticeably different cut to the ones he had been wearing mere minutes ago when John had left him. A tiny smile made itself evident on his face, but he didn't comment; most likely because his own face was similarly flushed and his jeans bore evidence of being hastily rebuttoned. Sherlock's shame at his loss of control was mollified slightly, seeing the reflection of it in his flatmate.

They ate in relative quiet; John related a story of one of his younger patients who had managed to get a fairly sizeable McDonald's toy up his nose that made Sherlock laugh, and he, when asked, told John about his experience in the shop where he had bought the bondage tape. He'd originally reached for the purple one that had looked most similar to the one that the victim had used, but a bubbly female sales assistant had assured him that he didn't want that one and redirected him to the black stuff. He had felt slightly odd in the shop: most of the other shoppers had been couples or terrifically awkward youths. As soon as he had walked in, he had wished he were not wearing his long, black coat.

They didn't talk about what had happened, how it had affected the both of them. John's eyes lingered on him more often than usual when he thought Sherlock was looking at his food, and for his part Sherlock felt the stares burn through his skin and make it flush pink. He hadn't felt quite this caught-out since he was fourteen and Mycroft had found him in the laundry desperately trying to wash his pyjamas before his mother found them.

John insisted that he help clean up after they had eaten, which devolved rapidly into a rather childish battle of John splashing him with the dishwater and Sherlock flicking him with the tea-towel in response, and so it was in amiable, slightly giggly quiet that they collapsed on the sofa, John reaching automatically for the television remote and then realising that the coffee table was on the other side of the room. He sighed. "Sherlock, can we…"

Sherlock had no intention of moving the furniture, so he made a contented noise and stretched out, throwing his feet over John's lap as though he hadn't noticed the start of the request. John tried to glare at him, but after a moment he sighed and sank back into his seat. "Can I use my computer, then?" he asked.

"I'm waiting for an email from a man I met on a case last year about clients of his matching the victim's description," Sherlock replied. "I'll need it back immediately if that comes in." He lifted his feet nonetheless for John to get up and retrieve the laptop from the desk. John allowed him to lift his feet back onto his denim-clad thighs with a wry grin when he sat down, promptly resting the laptop on Sherlock's ankles and wriggling into a more comfortable position in his seat. Sherlock could see the home screen of his blog reflected in the mirror on the mantelpiece.

He smiled contentedly and settled his shoulders back against the arm of the sofa, closing his eyes and allowing the happy domesticity to fill him up until he drifted away.

"Sherlock."

He awoke with a start to John's hand on his shoulder, shaking gently, his blue eyes fond. "I'm off to bed now," the doctor said gently. "You should head there, too. You'll get a bad back if you sleep on the sofa too much, it's really not long enough for you."

Sherlock smiled at his flatmate, sleep slowing down his body somewhat, and stretched indolently. John's eyes widened gratifyingly as his shirt strained against his chest. "Thank you, John," he murmured sleepily. John smiled back, and for a moment Sherlock thought he might bend down and kiss him goodnight and tilted his face up gently to accommodate the gesture.

John didn't, though, merely held out a hand to help him off the sofa. Flushing, Sherlock took it, careful to overshoot the gesture a little and bump gently into his flatmate's good shoulder, apologising with a quiet voice and yawning helplessly again. He took a moment to consider that before he met John he never would have allowed himself to be so vulnerable in front of another person, and yet now falling asleep and waking up slowly with John seemed easier than doing it alone.

There was a pause as they looked at each other, and then John smiled again and said, "Goodnight," as though he was reluctant to leave. Sherlock returned the line softly, and then the good doctor turned on his heel and made his way up the stairs.

When he was gone, Sherlock glanced at his violin. Mrs Hudson had ever-so-subtly gifted him the sheet music for Sarasate's Zapateado, and he had intended to attempt it today before the case and its associated dilemmas had overtaken his mind. It was a complicated, punishingly fast piece, though, and the first time he played it – especially when he had just emerged from sleep – it would sound screechy and clumsy and would not at all make for a happy John.

Besides, he can't have been asleep for longer than two hours. John was always telling him that four was the minimum he should be getting, and that was when he slept every night, which he hadn't, so perhaps he ought to go to bed and try again. He cast one last wistful glance at the violin, yawned, and then conceded the point and went to bed.

Lestrade rang early the next morning, startling Sherlock out of sleep. "Sherlock Holmes," he answered it, unable to keep the tiny hint of bleariness out of his voice as he tried to blink himself awake.

"Hi," the DI said pointlessly. "Look, there's – hang on, did I wake you up?"

Sherlock rolled his eyes, already climbing out of bed and shedding the pants he had slept in. "Well, Lestrade, it is… seven o'clock in the morning," he replied reasonably, glancing at his alarm clock and trying not to sound surprised at the time. Had he really slept the whole night through?

"Yeah, but you're you," the policeman replied, still sounding amusedly surprised. "John routinely complains about you being up at all hours of the morning. I just assumed you didn't sleep."

He sighed. "Everyone sleeps sometimes. Did you actually have a reason for calling, or did you just want someone awake to talk to?"

Lestrade laughed. "If I wanted someone to talk to, you definitely wouldn't be the one I'd call, awake or not. Look, there's been another murder. Sally thinks it's the same killer as the one we had at the beginning of the week, but they're a bit different. Thought you'd like to come and have a look."

"How altruistic of you," Sherlock commented dryly. "All right, text me the address and we'll leave in twenty minutes."

He hung up on Lestrade's snort, already riffling through his drawers for a clean pair of pants and trousers; he grabbed a shirt on his way out of his bedroom door, still flinging it over his shoulders as he stopped to click the kettle on. He was about to shout up the stairs for John when he remembered Mrs Hudson's reprimand the last time he woke her before eight a.m., and clambered up the stairs two at a time instead.

"John?"

There was an indistinct murmur from the other side of the door as he rapped on it; taking that as consent, Sherlock opened it and moved through into the doctor's bedroom, averting his eyes just in case John was doing something he wouldn't want Sherlock to see – it wouldn't be the first time he had burst into the room to catch a glimpse of a healthy-sized erection as John struggled to hide it from him, invariably leaving Sherlock desperately trying to cover a blush and look away before his own body began to react – but when he looked back John was sitting up in bed, clearly having been woken from rather deep sleep.

The doctor blinked at Sherlock's torso, reminding him of the fact that he hadn't buttoned his shirt as he came upstairs. "Is this a dream?" he asked, his voice dark and husky with sleep.

"I'm afraid not, John," Sherlock lamented wryly, buttoning his shirt briskly and grinning at his flatmate, wondering shyly whether John often had dreams which involved him half-dressed. "You need to get up, there's been another murder."

John sighed, running his hand down his face, but he swung his legs out of bed nonetheless. "What, like the one on Tuesday? The femme fatale?"

Sherlock lifted an eyebrow at his colloquialism, but nodded sharply. "Donovan certainly believes so, although it seems Lestrade has his doubts. I suppose we'll see." He flicked out his shirtsleeves and began buttoning his cuffs with a flourish. "Kettle's on. Tea or coffee?"

A surprised look met his eyes when he looked up. "Are you offering to make it?" his flatmate asked.

"No, I was wondering which I should expect," Sherlock replied, affecting a slightly affronted look. "Of course I'm offering to make it. I'm already mostly dressed. I expect you'll want to shower."

John stared at him for a moment. "You're not going to drug me again, are you?" he asked suspiciously.

Sherlock groaned in frustration. "It was only a suggestion, John, I won't bother if it's such a big problem for you."

"No," John countered quickly, clapping him gratefully on the shoulder on his way to the dresser, "coffee would be lovely. Thank you." Sherlock smiled weakly and left him to it, jumping back down the stairs.

Sleeping was actually quite nice, he mused as he rooted around for take-out cups in the cupboard. It certainly slowed down his reactions for a few minutes as he woke up and an hour or so as he settled down to it, but he felt relentlessly, irritatingly good this morning. No wonder John had been so cheerful the morning before.

John, apparently, noticed too. "You're very upbeat this morning," he commented, towelling his hair thoughtfully as he entered the kitchen. "Sleep well, did you?"

"Tremendously," Sherlock confirmed, holding out John's coffee. "And then I was woken up by a possible lead on my case. Perfect predictors of a good day."

The doctor grinned as he took the cup of coffee, sipping tentatively and then smiling at the lack of sugar and hallucinogens. "Right," he said cheerfully. "So where are we going?"

Sally Donovan stood in front of the corpse as though attempting to shield it from their view, her arms crossed and her usual disapproving frown fixed onto her face. Lestrade cleared his throat at her when they came into the room, giving her a pointed look. Sherlock smirked as she scoffed in annoyance and flounced away.

The second man had undressed slightly further than the first, and therefore looked a little less dignified in death, his torso bare and his purposefully-ripped jeans shoved down around his thighs. He was younger, too, obviously less personally successful than Montgomery. Rich parents, Sherlock guessed. Those were £200 jeans he'd bought ripped like that, and actual diamonds gleaming in three places on his left ear. They weren't the only examples of careless wealth flaunted about his person, and the bedroom itself was even worse. The degree to which the man displayed the wealth that he had inherited suggested huge levels of arrogance – he imagined a youth entirely used to female attention. Dominance would probably be more than natural to him, and it was completely possible he could get carried away more than once. Sherlock allowed one corner of his mouth to quirk upwards humourlessly.

He had been left face down on the bed, the twin globes of his glaringly-white arse presented quite comically. It seemed as though the murderer had simply cast him aside once he was dead. A quick examination of his neck showed that he had been strangled, and the –

"John."

The doctor raised his eyebrows expectantly; the tiniest gesture toward the body brought him over to bend and peer at the ligature marks on the man's neck. "Fingernails," John pronounced. Sherlock nodded shortly. The doctor plucked Sherlock's pocket magnifier from his hand to look closer. "From the angle it looks like she was holding him up by his neck. Probably tried to overpower him but he was stronger than her – but that would mean she had both hands around his neck and he had both free." John reached right into the inside pocket of Sherlock's Belstaff and pulled out his handkerchief, using it to lift the victim's hand closer to his eyes. "His fingernails are clean," he said thoughtfully. "He didn't try to get her hands away from him, so he must have been able to reach her, focused on hitting her instead of defending himself. I imagine she'll have considerable bruises."

He straightened, handing magnifier and handkerchief back to Sherlock, who had to frantically remind himself to breathe. He had only intended the doctor to confirm the crescent-shaped fingernail marks, not to point out their angle or assess any other aspects of the body. John's ever-increasing powers of deduction left him oddly breathless and the room was suddenly uncomfortably warm. He cleared his throat quickly. "Yes, very good, John, you're really getting the hang of this. Of course, the fact that he didn't try to remove her hands also suggests that she's smaller than he is – supported by the fact that she couldn't overpower him or he'd be on his back, and he doesn't look particularly strong or intimidating. So she's petite, must be attractive to get both of these rich and arrogant dominants interested in her… oh, and she's blonde, but we knew that already." He lifted with the handkerchief a long blonde hair from just below the pillow. "Call around hospitals and see if anyone who fits that description turned up last night with extreme facial bruises. And it's probably worth running her DNA through the system, but I doubt you'll find a match."

Lestrade carefully bagged the hair, frowning at the corpse. "Did you have any other theories, then?" he asked.

Sherlock shrugged. "John and I explored a theory last night," he said, studiously not looking at John as he said it for fear of the expression on his friend's face. "I sent messages to contacts that could help, but I haven't received replies yet – I'll call them once we get out of here. Knowing that she'll have bruises will help. Lestrade, help me roll him over," he commanded briskly. The three of them carefully manoeuvred the body onto its back, John wincing as the bedsheets stuck awkwardly to the corpse's groin area. Sherlock hummed absently at it. "She must have removed the condom from the same angle," he said. "What made you think this wasn't the same killer?"

The DI frowned awkwardly. "Mainly the lack of the tape that was on the last one."

Sherlock glanced again at the headboard; there was indeed no trace of the deep purple tape that had been on Montgomery's bed. "That doesn't necessarily mean anything," he said. "Good-quality bondage tape isn't supposed to stick to anything except itself, he could easily have used better stuff than Montgomery. Or used a scarf or tie or rope instead of tape. And not everyone who's into BDSM plays with bondage anyway."

"Or he could have wanted to show his mental domination of her rather than his physical domination," John interjected, looking up from the wastepaper bin. Sherlock blinked at him, aware that the other police officers in the room were staring at him too. The doctor coughed slightly awkwardly. "He could have ordered her to keep her hands there rather than just tied them there - rely on her mental submission to him rather than forcing her down. Has the same end effect, but gives the dominant partner a lot more control."

John's knowledge of BDSM techniques made Sherlock pause for a moment, not realising he was staring until the doctor lifted an eyebrow at him. He forced a careless smile. "That would certainly allow for the element of surprise - he had no idea when she would begin to disobey his orders and move her hands. It's definitely worth exploring, thank you, John."

The doctor smirked at his repeated use of the word 'exploring'. Sherlock was momentarily grateful that Lestrade was looking in the opposite direction as he allowed himself to imagine the scenario.

Something was going on there. He desperately hoped it was what he thought it was.

"No, Lestrade," he said brightly in the meantime, clicking his pocket magnifier shut after examining a series of marks across one hip that turned out to be impressions from the chain on his trousers. "It's definitely the same killer. Just because they didn't use the same type of bondage equipment doesn't mean anything – nobody carries a roll of bondage tape around in their handbag on the off-chance they'll meet someone interested in tying them up."

John snorted. "Not cheap bondage tape, anyway. If you're that prepared, you're going to want the good stuff."

Sherlock rolled his eyes. "I'll make a few calls, John and I will investigate a few other angles so that we can find her more easily," he said briskly, avoiding John's eyes again. Lestrade looked suspiciously from one to the other nonetheless before apparently deciding he didn't want to know and giving up.

"So that's it? I'll get Donovan to put a notice out to the hospitals and that's all we can do?" he asked, sighing resignedly.

"Relax," Sherlock told him. "Either you'll find her or we will."

John caught up with him at the bottom of the stairs out of the apartment building, his shoulder bumping comfortingly against Sherlock's upper arm. Sherlock shot him a grin as he opened the building's front door with a sweeping gesture, indicating the doctor should move ahead of him. "So, John," he said brightly, closing the door behind them with a snap. "You're not busy this afternoon, are you?"

The doctor's face split into a wry smile. "Looks like I might be getting that way," he replied easily. Sherlock laughed.

"Well, I have to call the people I emailed last night as soon as we get home," he said as they slid into a taxi. "A cup of tea would be lovely."

John rolled his eyes, but he nodded his assent. His hand rested calmly on the empty seat between them, palm down, looking slightly out of place, as though that was not where it naturally wanted to rest. Sherlock considered reaching out and placing his own hand on top of it, but decided against it.

Not yet, he told himself sternly. Not just yet.