A/N: Trigger warning for the often abysmal way the police handle reports of sexual abuse. Also, there were two places I could have split this and the next chapter; I chose the earlier one, which means that there's no romance in this chapter – but it also means that I've written about two-thirds of the next chapter already. Hooray!

They reached the pub before the police; Sherlock held out an arm to stop John before he went inside, glancing surreptitiously through the window. "We can't do anything until Lestrade gets here," he reminded him. "All we can do is keep her here. Let me do the talking."

John smiled softly and shrugged. "I always do," he replied easily. Sherlock grinned back.

The blonde was sitting at the bar, nursing something brightly-coloured and smiling at Henzell as he kept chatting to her while drawing lager from a tap. Sherlock wondered if she had sat down there of her own volition or if Henzell had taken her there on purpose so that he could talk to her and work at the same time.

"So there's more than one BDSM bar in London?" John asked quietly as they wove their way over there.

Sherlock rolled his eyes. "This isn't a BDSM bar," he replied, looking around at the perfectly ordinary patrons. "It's just a pub. The man at the bar doesn't own it, he just bartends here sometimes. He also runs a swing club at his house when he's not here. Some of the people from the club come here because they know him."

John shook his head, smiling ruefully. "It really shouldn't surprise me how well you know your way around the London BDSM and swing scene."

"I could name several reasons for a detective to be familiar with them," Sherlock told him sternly. "Not just finding murderers. Accidental deaths from erotic asphyxiation sometimes look like murder, and vice versa. It's a fairly tight-knit community, everyone knows everyone. Of course, there are people who enjoy and practise that sort of thing who never tell anyone except their partners, but if they're into BDSM, and they're looking for other people who are into it, someone in this community is going to know them. I know two people personally who know almost everyone else who could give me information I might need. You're quite right," he said, looking over at John as they reached the bar. "You shouldn't be surprised."

He lifted a confident hand to Henzell, leaning idly against the bar-top and ignoring the indignant set of John's face. "Jake!" he greeted brightly.

The barman looked up at him and grinned, trying unsuccessfully to keep the relief off his broad face. "Sherlock!" he returned, just as enthusiastically, as if they were old friends. "Good to see you! Scotch neat, is it?"

"Perfect," Sherlock replied. He had winced at the sound of his own name, but the woman didn't flinch or bolt. He supposed he couldn't expect Henzell to be bright enough to use a false name without being told first, but if she knew he was a detective surely she'd be on her guard around him. Sherlock Holmes had become a far more famous name than he would like. At least it seemed to be that ridiculous hat people recognised, rather than his face; he'd often wished that he had looked at the accessory he'd picked up from the theatre before putting it on, but he had to admit that his choosing such a conspicuous one had its advantages. "And a pint of lager for John here. And I know it's short notice, but if we could have a room in the back? We're waiting on a few friends but they'll be here in about five minutes."

Henzell nodded to show that he had understood the veiled reference to the police. "I'll start a tab," he said, tapping at the screen of the till in front of him. "Sherlock, have you met Charlotte? She hasn't been to the club in a while, but maybe you've run into each other?"

Sherlock turned to the woman, straightening into a more commanding posture and looking her up and down with a predatory expression. She smiled demurely, shivering slightly at the attention. Definitely an established submissive, then, not someone who was only in the game for revenge. Especially since Henzell's language suggested she'd been a member of his club for quite some time. "Sherlock Holmes," he introduced, watching her face for any flicker of recognition or panic as he held out a hand.

She took it without either, clasping it carefully. "Charlotte Wilson." Her hands were soft, and without feeling them too obviously he couldn't detect any obvious scarring caused by fingernails. Not that that really meant anything.

"Charmed." He held onto her hand for a moment after he felt her start to pull away, making sure they let go on his terms and not hers. "This is John Watson," he said carelessly, throwing a hand over his shoulder in John's direction but cutting the doctor off when he tried to reply. "So is there any particular reason you haven't been by the club? It would have been delightful to see someone like you there."

Charlotte blushed slightly. "I was in a relationship for a while," she said, turning away and draining the glass of violently red liquid. "Since it ended I haven't felt like going out. Tonight I sort of decided I was ready to put myself out there again."

Sherlock smiled wider, leaning towards her slightly. "Lucky me," he said, lowering his voice further. "What was that red monstrosity? Can I get you another, or would you like a real drink this time?"

She laughed shyly. "It was vodka and raspberry," she told him. "I'd love another."

"Good," he replied easily, gesturing to Henzell and nonchalantly sipping his own drink. He turned his attention more obviously to the bruises on her face, neatly covered up by concealer and foundation but still visible. They looked slightly older than he would have expected, but seeing the lengths she had gone to to cover them up it wasn't unreasonable to assume she had put salve on them to speed their healing. It seemed like the routine of someone who had to hide bruises often. She shifted self-consciously under his scrutiny, her hand twitching around the empty glass as though trying not to touch her face.

"I know what you're looking at," she said softly, "and I'd rather not talk about it. It's not a problem anymore."

Sherlock smiled again. "Of course," he replied. "I'll only say that I am very definitely not like him."

She laughed, light on the surface but with a slightly bitter undercurrent. "Ah, that's what he thought too," she said, lifting the drink Henzell offered her in a mock toast. Sherlock frowned, but before he could reply John kicked him gently under the bar; he looked up to see Lestrade and his team weaving through the bar towards them.

"Ah," he said brightly, gesturing towards them. "Our friends have arrived." He waited until Lestrade was standing right behind Charlotte before dropping the predatory persona he'd affected. "Charlotte Wilson," he said in his own voice. "This man is about to arrest you under suspicion of the murders of Stewart Montgomery, Charles Trent and Vincent Stephens."

Lestrade gave him a stern look before he could say anything else; Charlotte stood up abruptly, her face draining of colour. "What?" she cried indignantly. "Murder? - but what do you -"

He smiled nonchalantly at the officer - he knew technically he shouldn't have said that himself, but Lestrade didn't even know the woman's name. "You do not have to say anything," the DI interrupted her gruffly, catching her flailing hands and drawing them together behind her back, "however, it may harm your defence if you do not mention when questioned anything you later rely on in court. Anything you do say may be given in evidence."

Charlotte's face as Lestrade took her away was a mess with angry tears, confusion, indignation, and just a tiny hint of smugness. Sherlock frowned.

"What?" John asked, draining his pint and watching Sherlock swill the dregs of his scotch and stare at the police as they left the pub.

Sherlock sighed as the door swung shut between them, the people around the tables who had been momentarily distracted by the arrest turning back to each other as though nothing had happened. "Something's not quite right," he said softly. "Or rather, a lot of things aren't quite right that could be explained away by themselves, but all together… it could be nothing."

John shook his head. "They can all be explained away - not everything can be perfect, Sherlock."

He drained the glass in his hand and flicked it back down the bar, standing up with another sigh. "Well, we'd better follow them, either way," he said briskly, yanking a fifty-pound note from the inside pocket of his jacket and holding it out towards Henzell. "Thank you," he said to the barman as he took the money. "Keep the change – for your help."

Henzell stared at the fifty. "Thanks, Mr Holmes," he said, sounding slightly bewildered. John chuckled as they wove their way out of the pub.

"You're a sucker," he muttered when they were outside, Sherlock weaving his scarf back around his neck. "Fifty quid for a vodka mixer, a pint of lager and a scotch neat?"

Sherlock shrugged as he waved an arm for a taxi. "I look after the people who help me so that they'll help me again."

John laughed. "Yes, you do," he said, and there was a strange note to his voice. Sherlock watched him curiously as a black cab pulled up beside them. "Well, you fixed my leg the first time we met. Must have seen something you could use in me."

"I certainly saw someone who could run a lot faster without that ridiculous cane," he replied nonchalantly, sliding into the taxi first. "If I'm honest, it was more what you saw in me. You said 'brilliant' when everyone else said 'piss off'. I couldn't let that go."

He watched as John's smile grew, facing away from him into the window. At least it was the truth. "Match made in heaven, then," the doctor muttered to the glass. Sherlock smiled at him. It certainly was, though he hadn't quite known it at the time.

John, about before…

He could say it. He could – have the whole issue wrapped up before they even got to Scotland Yard and jump on the doctor the moment they got home. The idea was desperately appealing.

The cabbie coughed, a deep, dangerous, wet cough that made Sherlock shudder and jolted him sharply back into the moment. It had taken him so long and he'd had to be so certain of John before he could think about telling him; he couldn't reveal so much of himself with a stranger watching. Not to mention he wasn't sure he could keep his hands off John once the barrier had been lowered, not even for long enough to close the case. The balance between his desire to say something and his doubt in his own self-control was dangerously close.

Sherlock took a deep breath, then reached out and put a hand on John's knee instead. Without looking at him, John casually rested his own hand on top of it, staring out the window as though nothing had happened. Sherlock's stomach glowed.

Donovan was standing outside the interrogation room when they arrived at New Scotland Yard wearing a bitter, disgruntled expression; she sighed grumpily when she saw them, pushing the door open and attempting to stare Sherlock down as they passed her. Charlotte was sitting at a table, her cuffed hands resting on her lap, looking pale and frightened but still confused, and still with that tiny hint of smug pleasure. Sherlock frowned at her.

Politely, Lestrade had waited until they arrived before asking any questions. Charlotte eyed Sherlock angrily when he walked in. "Is he a police officer? Surely that counts as entrapment."

Lestrade smiled thinly. "Not too up on current events, are you, Miss Wilson? That's Sherlock Holmes. He's not with the police, he's a consultant."

"Thank God," Sherlock muttered, sliding elegantly into the seat beside Lestrade and pulling it away from the table so that he could lounge idly in it, looking far less concerned than he really was. Something definitely wasn't right – and yet so much was right that it couldn't be chance. She had to be the killer.

Lestrade reached out and placed a photograph on the table in front of her, watching her closely. "Stewart Montgomery," he said slowly. "Did you know him?"

Charlotte looked wistfully at the photograph. "Yes," she admitted. "I dated him for about a month. He broke it off a week before he died."

She didn't try to reinforce how much she'd liked him, how upset she'd been to hear that he was dead. That was the most common mistake people made, pretending to be too upset about the death of someone they'd killed.

Lestrade pulled out the second photograph and laid it carefully on the table beside the first. "And Charles Trent?"

"I met him once, at a bar about six months ago. We slept together. He wasn't very nice, so I never returned his calls."

Sherlock looked at John, frown still firmly in place. If Montgomery had broken it off with her, would he have agreed to sleep with her a week later? He thought back to that first witness statement, the idea that had sparked the whole role-playing exercise. She had approached him, and the barman hadn't thought he looked hostile or suspicious or even surprised; only smug and seductive. That wasn't the behaviour of a man being approached by a woman he had just let go. Unless she'd called him, arranged a meeting beforehand? She had approached him and they had talked briefly, and then he had taken control, reasserted his dominance over her, perhaps to remind her that he was in control, and there had been the tiniest hint of a five o'clock shadow on John's jaw –

Sherlock took a deep breath. "And you hadn't seen Trent since that night?"

"I told you," Charlotte sighed, looking back at the photograph, "he wasn't very nice."

Lestrade breathed out slowly and put down the third photograph. "Lastly, Vincent Stephens."

Charlotte sucked in a breath through her teeth, her face pinching. "I thought I must have misheard you when you said it in the bar. I didn't even know Vince was dead. We were together for about eight months. I mean, this was over a year ago, but I…" she shrugged, staring pensively at the table. "Vince was a great guy," she finished instead. "I'm sorry to hear he's dead. I didn't do it. I don't know anything about these murders."

"You have to understand why you're here," Lestrade said lowly. "You've had sexual encounters with all three of these men, and from what you've just said alone at least one of them treated you badly. You have to admit you had the motive to kill all three of them."

Sherlock narrowed his eyes at Charlotte as she sighed. "I know. But I don't know anything about this, I swear. I… all three of those men were regulars on the London BDSM scene, I'm not sure if you knew that – the community isn't that big, I can't be the only submissive woman who's known the three of them."

"Tell us about the bruises," Sherlock distracted softly, tipping his chair idly back on its hind legs, feeling John immediately fix his hands on the back so that it didn't tip. He smirked over his shoulder at the doctor before turning back to Charlotte, who was staring fixedly at her hands.

"The night I found out Stewart was dead," she murmured, her tone of voice making it quite clear she'd hoped she'd never have to talk about this again. "I… I went out. I wanted to drink to forget, you know - Amy, my flatmate, wasn't there, or she would have tried to stop me. I ended up drunk enough that when a man invited me into an alley it seemed like a good idea, until he put his hands on me, and then when I said no he gave me these," she gestured towards her face, "and then walked off."

Lestrade leaned forwards, frowning concernedly. "He didn't rape you? Just hit you and left?"

Charlotte shook her head, still not looking at them. "Don't tell me I'm lucky, or that I should be grateful or relieved somehow that he didn't rape me."

"We weren't going to," Sherlock said, slightly sharply with a glance in Lestrade's direction. He'd seen plenty of interviews of sexual abuse victims handled absolutely terribly by the police; a few times he'd even thrown the officers out of the room and conducted the interview himself, apologising profusely to the victims. It was a sorry state of affairs, he'd remarked to John afterwards, when he was more sensitive and polite than the police. He didn't think that Lestrade would make the same mistakes, but this was important and he couldn't take chances. That kind of attitude suggested that she'd tried to report behaviour like this before, so either she was telling the truth about how she got the bruises or she was recounting a true story from a different time. "Where were you when this happened?"

"Soho," she replied. "At the Ball and Chain, it's a -"

"Members-only BDSM bar, we know," Sherlock cut off, though Lestrade probably didn't know. If she didn't come back inside after being beaten, Eliza wouldn't have picked her out from the other small blonde women she'd mentioned. He sat up properly in his chair, subtly taking control of the interview from Lestrade. "Where were you when you heard about Stewart and Charles?"

She looked up at him and smiled shakily. "Stewart's murder was on the news. I was at home in the flat - Amy was cooking. She dropped something and I was too stupid with shock to help her clean it up. She kept trying to say things to comfort me, but she didn't like Stewart so I knew she didn't mean them. That's why I left the flat. And then Charlie - I was at work. Someone in my cubicle found out and the whole office was talking about it. It sounds awful, but I was kind of… pleased. I've already said he was horrible. I think I said something terrible, like good riddance or something."

Sherlock's doubts grew as the interview went on; her alibis for all three murders were shaky at best, but she could repeat them back to front and inside out with a genuine amount of thought and they didn't seem rehearsed. After an hour he gave up his chair to John, who was swaying where he stood and had an early shift tomorrow. After two he suggested that the doctor go home and let Sherlock deal with this, but John stoutly refused and attempted to pretend he hadn't been falling asleep in the chair while Sherlock paced frenetically and Lestrade patiently put question after question to Charlotte. When John fell asleep around midnight they left him that way, lowering their voices slightly and watching him to make sure he didn't slip out of the chair. By four a.m. their questions had derailed from asking about the murders and her relationships with the victims and turned to her home life, questioning her as a victim rather than a suspect.

He wasn't as surprised as he ought to have been when Donovan interrupted them with a panicked look and a phone at her ear to tell them there had been another murder.

"Where?" Lestrade asked, looking as though he was trying very hard not to punch the wall of the corridor she had taken them into.

"Kensington," Donovan supplied, hanging up the phone and tapping it obnoxiously against the meat of her palm.

The DI sighed. "We have to go. That interview was going nowhere anyway, we'd already guessed it wasn't her. Strange, though, that she'd dated all three of them."

Sherlock shook his head. "It's like she said. The London BDSM community isn't that big. And she didn't exactly date Trent."

Donovan shifted impatiently. "What do we do with her, then? Let her go?"

"Keep her until we've looked at the scene. You're right, she fit the profile of what we're looking for so closely it's a terrific coincidence." Lestrade nodded at Sherlock's words as though it had been his suggestion. "And when you do let her go, take her right back to her house. Actually walk her to her door, see if you can talk to her flatmate about her dating habits, whether she ever tries to talk her out of her weakness for the wrong kind of men. If she's not a killer, she's certainly got a high-risk lifestyle for domestic abuse."

They looked back through the observation window to Charlotte, picking absently at her cuticles and shooting anxious glances at the door. "Call for someone to sit with her while we're at the scene," Lestrade said to Donovan. "Get her a cup of tea, maybe breakfast."

Sherlock's eyes fell on John in the chair opposite her, head bowed, clearly still asleep. He smiled fondly. "I'll get John," he ventured.

Lestrade sighed. "Try to send him home, will you? He looks like he hasn't slept in days."

"He has work in three hours," Sherlock said, checking his watch with a tiny smile. "I'll be advising him to call in sick, at the very least."

Sherlock knelt in front of the doctor and shook him gently. "John," he murmured. "John, time to wake up."

John started, waking with a sharp breath in and focussing slowly on Sherlock. Within moments, he had registered his surroundings and adopted a look of dismay. "I fell asleep," he stated, sounding somewhat indignant.

"Yes, you did," Sherlock told him. "Come on, now, we've got to go." He looked over at Charlotte while he helped John to his feet. "Someone else will be in in about five minutes to continue the interview," he said, trying to smile at her. "It shouldn't be too much longer now. I'm sorry that we had to do this to you."

John frowned at him as they left. "Not the murderer, then?"

"Unfortunately not," Sherlock replied. "There's been another murder."

"Okay," the doctor said brightly, rolling out a few cricks in his neck. "Where are we going?"

Sherlock frowned at him. "You are going home," he said firmly. "You just fell asleep at an interrogation desk. And I suggest you call in sick for your early shift at the surgery, too."

John shrugged, earning a crack from his back as well. "I've slept now, I'll be fine. I'll call the surgery, but I'm coming with you to the new crime scene."

"John," Sherlock tried to say sternly.

"Sherlock," John replied in the same tone of voice. Lestrade snorted.

Sherlock sighed. "All right, fine. Let's go, then."