It turned out that John's landlady, who had expressly promised he wouldn't have to dance, was as underhanded and manipulative as her mad scientist tenant.

"John, this is Mrs. Avery," she said almost as soon as they entered the ballroom.

"Pleased to meet you," John said, taking the hand of a woman who looked to be about the same age as Mrs. Hudson.

"Oh my, what a dashing young man," Mrs. Avery said, smiling at him.

"I told Mrs. Avery you might be kind enough to accompany her for a dance," his lying, conniving landlady beamed.

But John was too much the English gentlemen to say no. As he walked out onto the dance floor he silently cursed Mrs. Hudson with as many Sherlockian social catastrophes as could be pulled off in a single night.

The couples took their places on the floor, and John desperately ran through everything Sherlock had taught him when he'd been preparing for his wedding. The song would be a waltz, Mrs. Avery kindly informed him. He knew he could manage all right if he could just remember the steps.

"I want to apologise in advance, Mrs. Avery," John said. "I think I've fallen down a set of stairs more gracefully than I dance."

Mrs. Avery laughed. "Not to worry, dear, it's all in good fun."

John took a deep breath and the music began.

From his position on the dance floor Sherlock watched John closely over Mrs. Hudson's shoulder. He was doing all right, only occasionally fumbling the steps. He had the same stiff posture as he'd had during his wedding dance. Sherlock had tried to explain to him that half the success of the dance is appearing confident and relaxed. John currently looked like someone had a gun to his head. Actually it was a bad metaphor because John was much more relaxed when someone had a gun to his head.

No, John your left foot…

"No, John your left foot," Sherlock said.

They were standing in the living room, furniture cleared aside for the purpose of the dance lesson.

John had stormed into the flat earlier that evening. "Well, that's it, I'm not getting married."

He still had a key to 221B. Mrs. Hudson had never asked for it back when they thought Sherlock was dead. Sherlock had never asked for it back afterward.

Sherlock looked up from his laptop, startled. "What?"

"My fiancée is insisting we do a waltz for the first dance."

Sherlock snorted. "Were you hoping for a quickstep?"

John glared. "Sherlock, this is serious. It's going to be humiliating when I step all over her feet."

"So, you're not getting married then?" Sherlock confirmed.

"Nope," John said, crossing his arms and dropping into his chair. "Better to just call the whole thing off, I think."

"Hmm," Sherlock said, returning his attention to his laptop. "Shame."

Several minutes went by.

"You don't—" John started. "You don't know how to waltz, do you?"

"Nope." Sherlock kept his eyes on the screen in front of him.

"Ugh," John said with his usual eloquence, "this is a nightmare."

"Why?" Sherlock wanted to know. "You said you're not getting married."

John sighed, "No, I am, but we could set the record for the world's shortest marriage if Mary dumps me at the reception for being shit at dancing."

"How likely is that to happen?"

John looked at Sherlock strangely. "I was joking. I don't really think she'll dump me over it. The whole thing would just be a lot less painful if I knew what I was doing."

"Fine," Sherlock said, standing up. He gripped the table he'd been sitting at and pushed it up against the wall.

"What are you doing?" John asked.

"I'm going to teach you how to waltz."

"I thought you said you didn't know how."

Sherlock rolled his eyes. "I know the basic steps. I thought everyone did."

John scoffed. "Yeah, maybe everyone who went to public school…" He trailed off looking up at Sherlock, who was standing directly above him. "What?"

"The chair will be easier to move without you in it."

"Oh." He got up. "You're really going to—"

"Yes."

"Ok then."

"It's bloody complicated!" John huffed when he'd been corrected, yet again, about starting with his left foot.

"It's not complicated," Sherlock said. He'd taken off his suit jacket and unbuttoned the top of his shirt. John was considerably more awful at this than he had anticipated.

John, in turn, had removed his jumper, his long-sleeved button-up, and was now down to a black t-shirt.

Sherlock moved from where he'd been watching John to stand beside him. "Watch my feet," he said. "Do what I do."

Sherlock demonstrated the steps slowly, aware of John clumsily mimicking his movements beside him. Sherlock played the music and they continued. When John seemed to get the hang of it Sherlock stepped away. He folded his arms and watched the doctor move through the steps.

"You need to look like you're enjoying it," Sherlock critiqued, "not like you're getting a tetanus jab."

"I feel like a right idiot," John muttered, still moving through the steps.

"You look a bit like an idiot," Sherlock agreed.

John stopped. "You can't call your student an idiot. What kind of instructor are you?"

"The kind that is a detective, and not a dance instructor." He paused the music.

John clenched and unclenched his hands. "Sorry, it's not your fault I'm complete rubbish at this pissing stupid fucking bollocks arsehole dance."

Sherlock was looking at his friend with raised eyebrows. "I wasn't aware a dance could be an arsehole."

John crossed his arms sulkily. "This one is."

"You'll look better when you relax. It's better to look relaxed and make mistakes than it is to be accurate with the steps but look like you're watching one of Mrs. Hudson's YouTube videos."

Actually, John's expression while he danced was remarkably similar to the one he had worn the night Sherlock had been bored enough to google 'Martha Hudson,' and shown John the resulting clips of her former exotic dancing days.

Sherlock moved to stand in front of John and took a step closer. He took John's left hand with his right.

John stepped backward. "What are you doing?"

"Believe it or not, waltzing is a two-person activity."

"Yeah, but—" Sherlock noticed a slight flush around his neck. "I just need to know the steps. I don't need to practice with a partner, do I?"

Sherlock did not restrain the eye roll. "Dancing is not two independent sets of steps mashed together. You'll have to lead her."

John dropped his head. "Bugger." He looked back up and met Sherlock's eyes. He straightened his shoulders. "Ok," he said, "tell me where to put my hands." Sherlock felt a grin tug the corner of his mouth. Soldiers fear no waltz positions.

Sherlock played the music and stepped forward. He took John's right hand and placed it on his back. He rested his left hand on John's shoulder. With his right hand he clasped John's left and raised it out to the side.

"How close… should we be standing?" John asked. There was just a thin gap between them.

"This is fine for a beginner's waltz."

"Is it different at different levels?"

"A professional can lead with his hips."

John cleared his throat. "Well, we don't, er—"

"We are not professionals."

"No, no, that's not, erm, we're not—"

"Relax," Sherlock said.

"I am relaxed." John squirmed.

"You are not relaxed. You are squirming."

"Well why aren't we moving?"

"We're not moving until you get used to the position and relax."

John stilled and took a deep breath. His eyes flicked up and locked on Sherlock's. Sherlock's muscles tensed but he willed them to ease. He was role modelling, after all.

"We'll wait until the beat comes around… One, two, three… No, your left foot. Again. One, two, three…"

John moved better with a partner. Apparently a sense of responsibility for another person's movements was motivating for him. John had a strong, innate sense of responsibility for those around him. The mark of a good soldier.

John's dominant streak, which mostly lay dormant during their work together (asserting itself only when necessary—a few memorable occasions), but which Sherlock had observed in his interactions with women and sometimes in their own domestic life when they'd lived together ("Sherlock, you will put your dishes in the dishwasher, or I will put your mould cultures in the dishwasher"), was activated by being placed in the leading position. Instinctually he used the hand on Sherlock's back to gently pull him forward and push him back in a way Sherlock didn't have to instruct him to do.

He stepped wrong several times, swearing under his breath, and Sherlock corrected him when he tried to pull with his left arm. But Sherlock had put the song on repeat, and they continued until John was making fewer and fewer mistakes.

John had relaxed considerably from when they started. Sherlock could feel the tension easing in the muscles across his back. John was not overtly muscular, although in the t-shirt his muscles were noticeably defined. He'd known John was strong—he'd certainly received enough evidence the night John knocked him over in a restaurant. The doctor was in good shape, and he could feel the strength in the grip on his back and the sturdiness of his shoulders.

Sherlock had had the advantage of living with John, when he'd walked around the flat in t-shirts and pyjama trousers, but for others it would be hard to tell the state of John's figure under the nearly comical number of layers he wore. T-shirts under button-ups under jumpers under coats—a Victorian lady in January could hardly wear more clothing. He hadn't seen John wearing just one shirt in a while and it was… agreeable to know he was still in good form.

When they had made it through the set of steps multiple times in a row without error, Sherlock decided it was time.

"Look up," he said to his dance partner who hadn't stopped watching their feet since they'd begun.

"Do I have to?"

"Yes."

Sherlock felt John's grip tighten on his back as if to stabilise himself. He raised his eyes and looked directly into Sherlock's. Deep, dark blue. John was looking at him intensely, as if holding Sherlock's gaze hard enough would prevent him from looking down. When they returned to the first position he let go of John's hand and stepped back.

"That's, er—"Sherlock pushed his hand back through his hair—"that's good. Erm, for future reference you don't have to look directly into your partner's eyes. You can, erm, look out at the dancefloor... Technically you should look left, over your partner's shoulder, to, erm, avoid collisions…"

John was looking at him oddly. Sherlock was aware he was babbling, but somehow that didn't stop him.

"I suppose you and Mary will be dancing just the two of you so, erm… collisions won't be… er…"

John gave him a concerned look. "A problem?" he suggested.

"Yes, that's it. So you can probably go ahead and look at her. You can make eye contact like, erm—" He gestured at the air between them.

"Are we done then?" John asked. Sherlock was surprised to hear a trace of disappointment in his voice. "I think I was just getting the hang of it."

Sherlock raised his eyebrows. "You—did you want to carry on?"

"Erm, sure, I mean, if you don't mind…"

"No, that's all right."

John stepped forward to fill the space Sherlock had made when he'd stepped back. He took Sherlock's right hand with his left and he wrapped his right hand around to Sherlock's back. The spot was warm from where John's hand had been before, and he felt the heat of his palm again through the thin material of his shirt. The music was still playing and Sherlock counted, "One, two, three."

John stepped forward with his left foot and they moved through the paces. John, either not understanding Sherlock's incoherent ramblings or disregarding them, looked directly into his eyes again. Sherlock was better prepared this time and he held his gaze firmly.

John kept his feet moving in the right steps. Eventually he broke the eye contact by dropping his eyes lower—not to their feet, he was being good about that—but just to the level of Sherlock's mouth. And then to his neck.

John fumbled, stepping forward and pulling Sherlock toward him when he should have been pushing him back. They collided and John stopped.

"Sorry," he murmured.

Sherlock waited, wondering why he hadn't let him go. The scent of John's hair was laced with honey and Sherlock remembered this was his favourite of John's shampoos (the better ones he'd convinced John to buy after tossing out the cheap ones that do more damage than good, back when he'd lived at Baker Street).

Sherlock kept his left hand on John's shoulder, but moved his right to John's hip, meaning to push him back into the correct position. John's left hand reflexively gripped Sherlock's arm as if to push it away, but he didn't. His eyes shot to Sherlock's and neither of them heard the door opening.

They both, however, heard Mrs. Hudson exclaim, "Good heavens!"

They dropped their hands as fast as if they had been burned. John spun around and walked a few paces away. Sherlock stopped the music.

"My goodness, I'm so sorry to interrupt!" his abhorrent landlady prattled.

"He's teaching me to waltz," John said hastily. "For my wedding."

She grinned. "You look like you're getting on well."

John raised his hand to his forehead.

Sherlock leaned back against the window. "Mrs. Hudson, if you insist on burdening us with your presence you may as well tell us what tiresome reason you have for being in our flat."

Sherlock realised his error as soon as he said it. It wasn't 'our' flat; John didn't live there anymore. Neither John nor Mrs. Hudson seemed to notice.

"Oh, Sherlock, I'm sorry, love, how was I to know you two would be up here… waltzing?" she gave him a sly wink. "I wouldn't have come up at all, but, John, Mary's phoned me."

John looked up, startled.

"She says she hasn't been able to reach you."

John walked over to his neglected phone on the kitchen table. Evidently it had been on silent.

"She was worried, so I told her I'd come up to check if you were here…" she trailed off. "Should I not tell her you're here?" she asked conspiratorially.

"No, Mrs. Hudson," John said with audible strain in his voice. "I'll give her a call. Thanks."

Mrs. Hudson walked to the door, but she turned on her heel.

"John, don't marry her."

Sherlock and John both snapped their heads toward her in surprise.

"What?" John asked, dumbfounded.

"Oh, love, you know how much I care about you. I'll support you in whatever you choose. But just… think about it. You still have time. I know you boys don't think much of my history, but I've learned a thing or two in my years and I can tell you it's better to change your mind now than later."

Sherlock had never wanted Mrs. Hudson to shut up less. Weddings were despicable, melodramatic displays of sentiment—wholly repugnant social constructs designed to cultivate embarrassing and frankly pathetic levels of emotion. If John could be reasoned out of such an appalling affair Sherlock would not hesitate to shake the hand of the person who did it. John didn't need to marry Mary. He didn't need to live with Mary either. He could live here, at Baker Street, like they had before.

"Mrs. Hudson, what are you—?" John started.

"Just think about it, dear. Be certain. That's all I'll say on the subject. If you choose to marry her you'll have nothing but my warmest wishes and total support."

She left the flat and John turned to Sherlock. "What do you think that was about?"

Sherlock was pulling the table back out from the wall. That was enough dancing for one night.

He shrugged. "She wants you to reconsider your marriage."

"Why would I reconsider my marriage?"

Sherlock sat down in front of his laptop. "No reason at all."

Mrs. Avery was terribly polite about John's mistakes.

"Don't worry, dear, you just need a little more practice," she said when the dance finished and John apologised again.

"The next should be a quickstep," she continued.

John shook his head, "I can't, er—"

She chuckled. "This really isn't for you, is it?"

John smiled in relief at her understanding. "No," he said, "it's really not."

"Well, that's all right, thank you for the dance. I think I see my nephew over there. Perhaps he'll be my next hostage." She winked at him.

John had no trouble finding his way to the bar. He had just paid for the whisky when the next dance started. He had a good view of the floor from the stool at the raised bar. He picked out Sherlock and Mrs. Hudson from among the crowd of dancers and almost choked on his drink.

Sherlock Holmes was a bloody brilliant dancer. He glided across the floor as gracefully as—well, as he did everything else. John had never met anyone so agile and poised. It was only logical that he would be an exceptional dancer. Sherlock's body was made for dancing like it was made for expensive suits.

Mrs. Hudson also seemed to be one of the better dancers on the floor. John supposed it wasn't entirely surprising, considering she had been a professional dancer in the past. He cringed as certain YouTube clips took their cue to pop up uninvited in his mind.

The quickstep turned out to be just as fast and formidable as the name suggested. John watched the complicated footwork of the dancers in awe. When the consulting detective and his landlady moved past the edge of the floor John watched as they successfully executed a complex set of steps before he swept her off again.

It occurred to John that Sherlock had lied a few years ago when he'd asked him if he knew how to waltz. First he'd said 'no' before admitting that he knew the basics. Now it was obvious that he'd known much more than the basics. John had been suspicious at the time—the detective had given him oddly specific instructions and critiques, and the ease with which Sherlock had been able to dance the steps opposite the lead suggested he knew more than he was letting on. At the time John attributed it to his wealthy upbringing and just being a ponce generally. But now he could see differently. Sherlock loved to dance. And he was damn good at it.

John continued to sip his whisky. He watched Sherlock: his posture, his movement. He remembered that evening at Baker Street. Sherlock had been a shockingly good teacher. Shocking because the discretion required to teach ran counter to his personality. John wondered if he could remember a time when Sherlock had been as patient as he was taking him through the steps that night.

Sherlock was a many-faceted being, John marvelled. Whenever you felt sure you knew him he showed you another side of his capabilities, possibilities. He was, in other words, fascinating. But John had always known that. He'd known it from the moment they met in the lab and the young scientist with the dark hair and flecked eyes had sent his head spinning. He'd been captivated enough to move in with him, to write a blog about him.

John watched Sherlock guide his partner across the floor as fluidly as if there were no one else present. As if the steps were as natural as walking. Mesmerising. The consulting detective was a violinist. The violinist was a chemist. The chemist was a dancer. Incredible.

John finished the whisky and ordered another.

The cab ride home was a giddy affair. Mrs. Hudson was overjoyed to have her boys back together in 221B, and she was in the highest of spirits in the wake of the ball. Sherlock had turned out to be a spectacular dancer; she had received compliments on their dancing all night. The evening couldn't have been more of a success. She sat backward in the cab gleefully watching the doctor and the detective struggling on the seat across from her.

"Sherlock, stop leaning on me. Mrs. Hudson, Sherlock won't stay on his side."

Sherlock was sitting next to the window and John was practically draped over him in a slump.

Mrs. Hudson giggled and Sherlock shot her a glare.

The two of them had found John at the bar, later in the night, chatting with Gail Perry's son over a few too many drinks.

"Hullo!" John had slurred upon their arrival. "This is Nathan," he gestured at the equally intoxicated young man sitting next to him. "Nathan, these are my…" He broke off laughing.

"I'm Sherlock," Sherlock had said, offering his hand stiffly to the tall, auburn-haired gentleman, who shook it warmly.

Mrs. Hudson already knew Nathan Perry. He was a sportswriter for the BBC, a fact Gail wasn't letting anyone forget. He was younger than John, the same age as Sherlock, if she remembered correctly. He greeted her cheerfully.

"We are both better at drinking than dancing," John announced.

"And we're not that good at drinking," Nathan snorted.

They dissolved into giggles.

"I think it's time we went home," Sherlock said sternly.

Mrs. Hudson didn't miss the way he stepped forward, territorially placing himself slightly in front of John. She sighed inwardly. It was funny how in some ways young men were all the same, even Sherlock. He didn't seem to be aware of the unconscious shift in his stance. But Nathan stood up, body probably instinctually reading what his mind was too busy with alcohol to notice.

"John, I think they're better at drinking than we are," Nathan said, swayingly observing their stability.

"Yes," Sherlock said, impatience clear. "We're so good at drinking we haven't drunk anything."

John laughed into his glass.

Nathan nodded. "That is good."

John had stood up from the stool, catching Sherlock's arm to steady himself. Mrs. Hudson had smiled at how readily the two of them depended on each other, leaned on each other…

"I am not leaning on you. You are leaning on me," Sherlock insisted. He twisted in the cab seat, putting his hands on John's shoulders and sitting him up straight.

"Mmm," John said. "Difficult." He slumped back onto Sherlock's shoulder.

Mrs. Hudson giggled again and Sherlock slatted his eyes at her, as though his current position as a pillow were her fault. But when he looked back at John his expression softened.

"D'you mind?" John muttered sleepily.

Sherlock hesitated, an expression briefly flickering over his face that Mrs. Hudson had only ever seen on him when he looked at John. "I don't mind."

Mrs. Hudson's heart melted.