"John."

John let go of the spoon he was using to stir his coffee, round and round the cup, creating a small whirlpool. Harry was looking at him sternly. As though he were the one that deserved lecturing for his behaviour. He leaned back in his chair; the cheap metal scraped against the floor of the cafe. He watched his sister's expression soften from reproving to concerned. He didn't know which was worse.

"I'm sorry about your marriage," she said.

She didn't know what she was talking about. That wasn't her fault though. He hadn't told her anything. It was her fault though. If she hadn't been such a rubbish older sister he might have told her more.

John shrugged. "Well, the wedding wasn't important enough to attend; I don't know why the divorce should matter."

He'd just wanted the name of her divorce lawyer. The one she used when she ended things with Clara. He had called her up thinking she would give him the name, maybe some brief condolences, but nothing exceeding a few minutes. Then they could both go back to their separate worlds where the other only existed for a day at Christmas, and sometimes not even then.

She had asked where he was staying. He told her he'd moved back to Baker Street. There had been a silence on her end of the phone.

Harriet was five years older. The age gap was too big when they were young. From the day they brought him home his parents had made her the babysitter. Watch Johnny, Harry. He interrupted her life—took the spotlight and gave her responsibilities when she'd had none. Watch Johnny, Harry. And she had resented him for it. She was sixteen when he was eleven, and she was made to stay home every Saturday night so his parents could go out. And that was even before their mum died, and their father had needed help with everything. John understood. But at the time it hurt. She was cruel, making no secret of the fact that he was nothing more than a burden. And John, recognising her lack of love for him from an early age, had been as difficult and nasty back toward her as possible. The damage was too deep, too long-lasting to be repaired just because they were adults now with better perspective.

He was shocked when she wouldn't agree to give him the information unless he met her for coffee. She had something to say to him. John was on the verge of telling her he'd have no trouble finding a divorce lawyer elsewhere when she said, "John, please. I think it's important."

Harry dropped her eyes to her coffee, but she took the comment about his wedding in stride. "I won't play at anything by saying, 'I know I wasn't the best older sister' or some bollocks like that. I was anyone's worst nightmare of an older sister and you were a piece of shit little brother."

John scoffed, "Is that what you came here to tell me?"

"No." She looked at him hard. "I want to tell you it's ok if you love him."

John blanched, caught completely off guard. But he recovered quickly. "Really?" he laughed humourlessly. "Are you giving me permission to be gay? I'm not, by the way, but thanks. I'll remember it the next time I feel like picking up a bloke on my way home. I'll think, 'This is ok because Harry says I'm allowed.'"

She regarded him silently. Normally she would rise to the bait, call him a twatface and storm off. But this time she was quiet. She let the silence go on until John felt uncomfortable and even slightly embarrassed by his outburst. He crossed his arms and sank back into his chair. He supposed they had taught her this strategy at her AA meetings.

"I have something I want to say to you, and I want you to listen. Even if you completely disagree with it I want you to listen, and not say a word until I'm done speaking."

"Why should I do that?"

"Because I don't do bollocks like graduations and funerals and weddings, and I know I'm better out of your life than in it, but believe it or not I do care about you."

John rolled his eyes. No, she didn't do any of those things. She didn't even attend their father's funeral, let alone help organise it.

"I said 'believe it or not,'" she snapped. "I don't care whether you believe it. It's true."

Touching. It was probably a good thing she hadn't come to the wedding. What with Sherlock and a murderer and the bride being an undercover assassin, the last thing that wedding needed was Harry Watson.

"My life is a mess, you know that. I haven't had anything I could give anyone in a long time. So, please, do me a favour and just let me say this. I want to feel like I've done something right for you, for once."

John cleared his throat. He knew it must have been as unpleasant for her to come here as it had been for him. "Fine."

"Promise you won't say a word."

"Fine."

She took a breath. "If you loved him, it wouldn't mean you're gay."

John lifted his eyebrows sceptically. A man loving another man was the definition of gay, the last he'd checked.

"We live in a revolutionary time for sexuality."

Oh god. There must be a wasp nest he could step on, or something better he could do than listen to his lesbian sister give him a lecture about sexuality.

"People are finally getting it through their thick heads that the world is not divided into 'gay' and 'straight.' Those words are just labels, and they don't work nearly as well as people think. If you loved him, it wouldn't mean you were wrong in dating women all your life. It wouldn't mean you've been gay the whole time and didn't know it or some stupid shit. All it would mean is that you fell in love with someone else. Just because your type tends to be female doesn't mean you're incapable of being attracted to a man."

John's eyes flashed up at her. He opened his mouth to protest, but bit it back, remembering his promise.

"It has nothing to do with 'turning gay,'" she continued, anticipating his argument. "If you were attracted to him, it wouldn't mean you suddenly like men when you never have. It would only mean you like him."

John let his eyes fall back to his cup.

"Sexuality is a scale, and no one is one hundred percent directly on either endpoint. Not me, and not even you, with all of your girlfriends. Everyone has the potential to fall in love with someone of either gender. It's less likely for someone closer to one side of the spectrum, but it's not impossible."

Unbidden, a memory of Irene Adler in the abandoned Battersea power station appeared in his mind.

Are you jealous?

We're not a couple.

Yes you are…

Who the hell knows about Sherlock Holmes, but – for the record – if anyone out there still cares, I'm not actually gay.

Well, I am. Look at us both.

Irene Adler was gay. She was living with a woman when they met her; she liked women. But she'd fallen in love with Sherlock. And she had assumed that John, straight, had done the same. She was gay and he was straight, but look at them both. Weren't they both living and breathing for Sherlock at that point? And this is what Harry was saying. They hadn't spoken in a year, and yet here she was now, telling him the same thing Irene Adler had told him years before.

"It's not impossible," Harry repeated, bringing John's attention back. "Look, you can bugger off and forget I said anything if you're positive you could never love him. But I've read your blog, John, and the way you write about him, the way you describe him—I just don't want you to be a dickhead and automatically rule out the possibility just because you believe 'straight' is some kind of authoritative, prison cell of a concept. I have friends from all points on the spectrum, and I've had friends who've made themselves miserable over these stupid labels. Stupid words. I thought I could save you both time and pain by telling you what it takes a lot of dumb twats years to figure out: Don't let a word prevent you from doing whatever the hell you want. You shouldn't give a fuck about what label it would fall under, or what anyone else would think. You're a free adult. Why should you care if some random wankers can't categorise you into their simplistic little thought boxes? You don't owe anyone anything, and it's none of anyone's goddamn business what you do in your own flat."

John raised his eyebrows at her increasing vehemence and she checked the rise in her voice, taking a breath. Clearly she had strong opinions on the subject. She'd been living the controversy herself since she was fifteen.

When she continued her voice was more even. "It's hard enough to find happiness in this hellscape," she said, glaring out the window facing the main street behind him. "Don't make yourself an obstacle in the way of yours. Life is too short."

John opened his mouth but Harry cut him off. "Just think about it."

They sat in silence for a moment.

"If it's the sex you're worried about, I hear a lot of straight couples specifically choose to do it that way, so the idea shouldn't be too foreign to get used to."

It had been the wrong time to take a sip of his coffee. John choked. "Jesus Christ, Harry!"

She gave him a wry grin. "Do you hate me?"

He smiled in spite of himself. "Yeah, definitely."

"Oh this poison!" Sherlock couldn't help saying out loud for the second time. "Absolutely delightful." He reached for another blood film and readjusted his microscope.

"You know it's fine," John said from where he was finishing his dinner at the kitchen table, "if you say that when it's just the two of us here. But I hope you haven't forgotten our discussion about not calling things that kill people 'delightful.' At least not in front of sane people."

Sherlock was not really listening. David Rodgers' autopsy results had come in and he'd spent the morning at the lab analysing the victim's blood. He'd found poison, as predicted. (Of course Rodgers hadn't died from the stab wound, it would take Anderson-level blundering not to have seen that.) But what kind of poison? He was England's unofficial expert on poisons, and this was not something he'd seen before. It was something new.

"It's genius—virtually undetectable by standard autopsy," Sherlock said to himself and by proxy to John. "I was only able to find it because I was looking for it."

John cleared his plate and came to stand behind Sherlock's chair. "How does it work then?" he asked.

Sherlock could feel him leaning slightly over his shoulder to look at his notes. The familiar smell of wool and toast mingling with the unique, warm scent of John's skin enveloped him. Sherlock had an unusually sharp sense of smell and a remarkable scent memory. It allowed him not only to pick up but to differentiate with unerring accuracy between barely lingering traces of perfumes, tobaccos, and even deodorants. Considering this and the fact that there was no one he spent more time in physical proximity with, John's scent was as familiar to him as his childhood bedroom, as instantly recognisable as the smell of blood, formaldehyde, propane—It was different though, because it was softer than any chemical or perfume and certainly more agreeable. But despite its subtlety Sherlock could pick it out of a crowded place and know John was there even before seeing him. He found it unexpectedly… nice, even comforting in a way no other human's was. John's scent was an integral component of 221B, and the flat had never smelled right when he wasn't living there.

"It suffocates the body from the inside," Sherlock explained, straightening in the chair as he realised he had unconsciously leaned back. "It lowers the victim's blood pressure to dangerous levels which eventually results in—"

"Hypoperfusion," John cut in. "The organs don't receive enough oxygen, the body goes into shock and shuts down."

Sherlock grinned into the microscope. He had many reasons to be grateful that John was a doctor and not an accountant.

"But a person would notice if his blood pressure dropped that low," John added. "Why wasn't Rodgers checked into a hospital when he died?"

"Because the poison increases its effects exponentially. It starts slow, just a few basic symptoms of hypotension, which almost any otherwise healthy adult would ignore. It increases in very small increments. The victim doesn't notice. And then BAM"—Sherlock slapped his hand down on the table—"he's in shock. Confusion. Delirium. No time to call the ambulance. Dead."

"Please don't enjoy this so much."

Sherlock smirked. He leaned back again, speaking to the wall opposite but feeling John's presence behind him all the time. "As far as poisons go this one is rather brilliant. The murderer distances himself from his victim by a matter of weeks and there's no poison found in the autopsy. He gets away clean."

"An autopsy really won't catch the poison in the blood?"

"No. It's only a catalyst. It triggers an effect that tricks the body into killing itself. Evidence of the poison could only be found by someone who knows exactly what he's looking for. And no one knows that, except me."

"How did you know what to look for?"

Sherlock turned to give John a scathing look. "I am arguably the best chemist in England and I specialise in poisons. I had an idea what to look for."

"Modest as always," John muttered, walking over to his chair and dropping down into it.

"Modesty is a waste of energy. It accomplishes little more than to cloud facts with half-truths."

"Can I quote you on that?" John asked, opening his laptop.

Sherlock returned his attention to his notes.

"So the question is," John said after a minute, "who invented it?"

"That is indeed the question," Sherlock murmured absently.

"You think it was Moriarty."

A pause.

"Such an assumption would be purely guesswork at this point. Best not to make assumptions with insufficient data."

"What about the scars? Do you think the scars are connected to how he was poisoned?"

Sherlock had scrutinised the corpse Molly wheeled out for him that morning: David Rodgers—the corpse from the alley, but unclothed this time, allowing him to do a more thorough examination than he had been able to do on the street. He'd texted the photos on to John at his surgery. There was nothing particularly noteworthy about the body—thirty-five years old, fit, a regular runner judging by his muscle tone—except his thighs. On the otherwise unmarked, un-tattooed, unblemished skin, thin silver scars latticed the man's inner thighs. In a word: Odd.

Sherlock turned in his chair to face John. "Either directly or indirectly, yes. The pattern of scarring is too unusual. It would be a considerable coincidence if it was entirely unrelated to his murder."

"You're sure they weren't self-inflicted? I've seen scarring like this before. The location is right for it, upper-thighs makes it easy to hide—"

Sherlock rolled his eyes. "How old were the patients?"

"Well, typically fourteen or fifteen years old but—"

"No. He's a successful lawyer in his mid-thirties with no history of anxiety or depression. I searched his flat this afternoon. There's nothing there to suggest hidden angst." Sherlock scoffed the last two words.

"So what's your idea then?" John returned with an edge in his voice that Sherlock felt prickling the back of his neck. He narrowed his eyes.

"I can tell you the cuts were made by different knives at different times. I can tell you the width and make of the blades. However, I need more data to form a viable theory as to the circumstances in which they were received."

"In other words, you don't know."

"There are many unknowns in this universe," Sherlock snapped, "including how you manage function on a daily basis with such a miniscule store of knowledge in your brain."

John lapsed into silence and Sherlock was able to return his attention to his work. But after just five minutes he was looking into the microscope when he felt John's presence close at his side. He looked up and John was standing over him with his arms crossed.

"Why did they stab him then?" John was nothing if not tenacious. "If an autopsy wouldn't find the poison, why bother trying to hide it by making it look like a stabbing?"

"The poison is new," Sherlock said, tilting his head to admire John's ability to look defiant in a wool-knit jumper. "My theory is they're testing it and they don't want anyone looking too closely at it before they've had a chance to get it right. A stabbing rules out the need for an autopsy completely and they think they're safe."

"Weren't counting on you though." John smiled tentatively.

John was like a soldier in Kevlar: His ability to withstand Sherlock's outbursts must be medal-worthy.

Sherlock felt himself smiling in return. "Perhaps not."

If the poisoner wasn't counting on him investigating it was a strike against the Moriarty theory. However, if he knew Moriarty, and he was fairly sure he did (at least better than anyone else), this murder could also be a message for him. A clever poison saying, 'let the game begin (again).' Sherlock allowed himself a moment to appreciate the circumstance: competing with a dead man. He had to hand it to him, the mad genius had truly taken 'never say die' to a new level.

"Why did they choose him though?" John asked, looking at the picture of Rodgers.

"Not why," Sherlock said, swiftly scribbling a note across his calculations. "When."

"When?"

"According to these results he received the poison just over two weeks ago. I would estimate sometime between the seventh and the tenth of October."

"Ok," John said, returning to his laptop to type the note. "And how about the movers who stuffed the body into the armoire? Any more info on them?"

"Two men, brothers, late-twenties. Lestrade's holding them until the trial. He's got enough evidence to strap them with a long sentence. Said he offered to reduce it for the name of the man who hired them, but they won't talk."

"Well, that's a dead end then."

"Hardly. It tells us the person they're working for has power and influence. These men would choose years in prison over the consequence of revealing his name."

"Sounds like Moriarty again."

"Could be. Or someone close to him."

"Are there any of those people left? I thought you destroyed his network."

"Abroad, yes, but in London…" Sherlock rolled his shoulders to stretch them and stood. He turned around and leaned back against the table. "His closest agents were—still are—well protected. Moriarty would have known that his death was a possible outcome of our confrontation. Clearly, as he showed with vivid performance, it was an outcome he was not entirely averse to. Of course he would have prepared his closest operatives with instructions to carry out should he not return. We know he must have had powerful allies here in London, but there's no evidence connecting anyone to him."

John was looking at Sherlock with raised eyebrows. "So this could be it then. This case. It could lead us straight to Moriarty, or at least one of his top players."

Sherlock was silent as John voiced what he'd deduced almost from the very beginning.

"Might run into bit of trouble then," John said, giving Sherlock a half-smile.

Sherlock returned it. "Might do. If I promise you danger will you come?"

"I would come with you to catch Moriarty and his gang even if all it involved were days' worth of paperwork."

It occurred to Sherlock that John was the only person who ever made smiles want to break out across his face. He attempted to stifle one now as he said, "John, your courage is truly impressive."

"Yoo-hoo!" came Mrs. Hudson's voice through the door barely a moment before she opened it. She was carrying a large plate of biscuits covered by cling film. "Hello, boys," she said looking back and forth between them. "I hope I'm not interrupting anything."

"How could you possibly be interrupting anything?" Sherlock wanted to know. "Our time is entirely occupied by trivia. We do nothing but wait in anticipation for your intrusions."

"Oh Sherlock, you get bored of everything. When are you going to get bored of sarcasm?"

"As soon as it stops suiting my purposes so nicely," Sherlock said, moving from where he was leaning on the table to drop down into his chair across from John. "I would ask you to have a seat, but you're clearly just on your way out."

"Oh, no thank you dear, I'm just on my way out. I only wanted to pop in to drop off some biscuits," she said, walking to the kitchen and placing them on the worktop. "Homemade; I thought you might like them."

"Thank you, Mrs. Hudson, that's very kind of you," John said with his unerring ability to be tactful when he felt the situation called for it. Sherlock didn't know where he found the energy.

"Why don't you get right to it and tell us what favour you need," Sherlock chimed in. "I'm sure I'll say no directly, but I believe John will require time to work out some kind of polite wording for a refusal."

John shot him a glare. Sherlock took it in stride. If he had an unmarked corpse for every glare John threw at him he would be a happy detective.

"Now that's not fair, Sherlock, how did you know I was going to ask you for a favour?" Mrs. Hudson looked put out.

"'Homemade.'"

"What?"

"You said the biscuits were homemade. You often make biscuits but you don't bother to say you made them because it's obvious. Specifically mentioning that they're homemade now is your subconscious way of emphasising that you put time and effort into something for us, which suggests we owe you something in return. Such as," he drawled for flourish, "a favour."

"Well," Mrs. Hudson said indignantly, "as a matter of fact I did want to ask a favour."

"Shocking," Sherlock said, rolling his eyes at John.

"Sherlock," John said in his best warning tone before looking back up at their landlady. "What can we do for you?"

"Well"—she shifted her weight on her feet, suddenly nervous—"I was wondering…" She hesitated. Perhaps this was going to be more interesting than he'd thought. "Well," she said more firmly this time, "it's just that my charity, you know the one I help out with from time to time?" She received blank looks from both Sherlock and John but continued bravely. "There's a ball on Thursday to raise money. The man I've been seeing—"

"The bank clerk who's been divorced twice, has two children, three grandchildren, asthma, and a secret obsession with Star Trek?"

"Oh Sherlock you make everything so difficult"—she took a deep breath—"Yes, that's him. We planned to go together, but just this morning his daughter called with some kind of scheduling emergency and now he has to look after his grandchildren on Thursday."

Sherlock sighed heavily, "And you want me to accompany you to the ball."

"Actually," she said hesitantly, "I was hoping John might come with me."

John looked up in surprise. Sherlock gave a short laugh, "John? But he's rubbish at dancing."

"Hey!"

"Oh come on, what do you want me to say? That you're a natural? Move over Nijinsky, John Watson's taking the stage?" He knew John wouldn't get the reference to the legendary male ballet dancer, just as he never got any of John's pop culture references. Sherlock had managed to keep his love of dance a secret so far. He'd told Janine as a necessary confidence to ensure her affection, which he'd needed to exploit later. The only other possible giveaway had been when he'd taught John to waltz for his wedding. But then it seemed John had put his knowledge of the steps down to his public school upbringing and hadn't enquired further.

John cleared his throat. "Erm, he's right, actually," he said to Mrs. Hudson. "I barely managed my wedding dance, and if I did it was only because he taught me—"

"It's not about being a good dancer!" Mrs. Hudson assured him. "I just need someone to escort me. And I thought I'd have better luck asking you than Mr. Sulky over here."

John laughed and Sherlock glowered.

"Might have to remember that one for my blog," John said mirthfully. "'Scotland Yard baffled, calls in Mr. Sulky.'"

Mrs. Hudson and John were both giggling and Sherlock stood to let his glower radiate further. "There's a lack of school children present for such childish humour," Sherlock said sulkily.

"I'm sorry, love," Mrs. Hudson said, regaining her composure. "It's just that I thought you'd have no interest in something like a charity ball. But of course if you'd like to come…" She trailed off as if she couldn't imagine him saying he would, that the sentence wasn't even worth finishing. He'd kept his secret well.

"I'd be happy to take you," John said, standing as though he were accepting a mission. "After everything you've done for us I'd be glad to return the favour. As long as I don't have to dance."

Mrs. Hudson grinned from ear to ear. "Oh, wonderful! John, thank you." She took his hand and pressed it affectionately. "You certainly won't have to dance. Just being as handsome and charming as you are will be more than enough."

John looked down uncomfortably.

"I'm afraid it's a rather posh affair. Black tie, you know how these things are," she looked worriedly at John as though he might back out.

"No problem," he said. "I'll find something."

"Perfect!" she smiled. "Well, I'd best be off then—"

"I'll go," Sherlock said, crossing his arms and half-sitting on the arm of his chair.

They both turned to look at him. "What's that, dear?" Mrs. Hudson asked him.

"I'll go. I'll dance. I can dance." Goldfish need goldfish-level explanations. "I'm good at it."

"Really?" It was John asking.

"Really."

"Oh, well—well that's lovely!" Mrs. Hudson trilled. "Thank you, Sherlock."

"In that case you won't need me," John said, a note of relief in his voice.

"Oh, erm, I'd still be glad if you came…" She cast a concerned glance over at Sherlock. "Actually, John, can I have a word? Sherlock, I'm thrilled you'll be my dance partner. I'll look forward to Thursday."

John directed a puzzled expression at Sherlock before following Mrs. Hudson out into the hallway.

The door shut and in a flash Sherlock was pressed up against it.

"You know how he is," Mrs. Hudson was saying. "Would you mind—would it be all right if you still plan to come? You know how Sherlock forgets about these things. You could come in case he has to run off at the last minute, or you know, in case he doesn't."

"What do you mean?" John asked.

"It's just—well, he's Sherlock. I can't have him offending everyone there. The ladies on the board are—let's just say their sense of humour isn't as good as mine." Her voice picked up its insistence. "He's better when he's with you, John. At the very least you could stop him from causing a scandal by announcing who's sleeping with whose husband—"

"I'm not his caretaker." Sherlock could hear the slight bristle in John's voice. "And I can't say I'm all that bothered about the secrets of a bunch of humourless adulterers."

Sherlock grinned.

"I know, I know…"

A pause.

"I'll go."

"Really? Will you?"

"But only to prevent him from shouting weirdly specific criticism at the musicians."

Sherlock recalled the reference to John's wedding. However, he maintained there was nothing 'weird' about preventing a violinist from butchering a Mozart classic. One would expect a so-called professional to recognise the difference between forte, mezzo-forte, and fortissimo, and that he should be reprimanded upon his failure to do so.

"I'm not going to spend the whole night trying to stop Sherlock from being Sherlock," John continued.

"Fine, fine, fine," Mrs. Hudson replied hastily. "It'll be worth it anyway to see the looks on their faces when I show up with the two of you. You'll be the handsomest men there. By a long shot," she added.

Sherlock could practically hear John's embarrassed silence through the door before Mrs. Hudson continued, "Do you think Sherlock knows how lucky it is for him that he's so pretty?"

"Right," John said abruptly, "we'll both be there, so don't you worry. See you soon, Mrs. Hudson."

Sherlock sprang away from the door and just managed to grab the closest slide from the table when the door reopened. He pretended to study it disinterestedly as John walked back into the room.

"I guess I'm going as well then." Out of the corner of his eye Sherlock could see him flexing his hands the way he did when he was anxious.

"Fine," Sherlock muttered, not looking up.

"You know," John said, "I think we have an abnormal relationship with our landlady."

Sherlock didn't respond. He didn't know anything about normal relationships.