Sherlock was uncharacteristically jittery for most of the ride. He looked rather pathetic, actually - he was all dressed up in that mouth-wateringly tight black leather and sparkly fishnet, but his shoulders were slumped and he kept looking out the window like a small child who knew he was headed for a long day at church and would much rather be anywhere else. The combination was incongruous and gave John second thoughts about the whole affair.

"We don't have to do this, you know," he said.

Sherlock glanced at him, then back out the window. "Don't patronize me."

"I mean it - I could go alone, ask around, and report back. If you don't get off on this kind of thing, you're going to find Restraint a bit shocking. And probably distasteful. And since you've never done this before-"

"What makes you assume that?"

John eyed his flatmate. "The fact that instead of practically vibrating like you usually are when we've had a breakthrough in a case, you're hunched in on yourself and you actually look self-conscious in that outfit."

Sherlock immediately straightened his shoulders. "Don't assume I'm naive just because I've never been to a sex club."

"Aren't you?"

He arched an eyebrow in his John-I'm-disappointed-in-your-tiny-brain look. "My past experience hasn't been entirely vanilla, John. And I do take in information from other sources, much as that might surprise you."

"Fine, fine." John was already wishing he hadn't brought it up. "I'm not trying to pry, just - observe now and analyze later, all right?"

"Why?"

John huffed out a long breath. "Because I'm nervous too, okay? Not about the club - everyone's very discreet and it's a good environment to play in. No complaints there. But I've never had you there with me, and I'm finding that's a bit more exposure than I'm used to. I've never played in front of someone who could notice the way I hold my elbow when I wield a whip and deduce my entire sexual history from that. It's kind of unnerving."

". . . You have a whip?"

John leaned his head back against the window and closed his eyes. "Yes, Sherlock, I have a whip. And quite a few other things in the bag at our feet. Want me to plan to use it tonight?"

There was a long pause before Sherlock finally answered, "I don't think so."

"No impact play, then?"

Sherlock shifted in his seat. "Never tried it."

"Thought so." John sighed. "Look, all I'm saying is, I do intend to have a long talk with you once we get back to the flat. About whatever happens tonight, both for the case and between us. But I'd really appreciate it if you can just focus on the case first, and leave all the other stuff for later."

Another pause. "I can do that," Sherlock said slowly.

The taxi lurched to a stop. "Good," John said. "Because we're here."

"You're still nervous." John pushed Sherlock into an alcove in the antechamber, just past the coat closet, and blocked him in with his body. "Stop worrying about it."

Sherlock looked away. "I'm not worried," he lied.

"Yes you are." John dropped the duffel and reached up to grab the nape of Sherlock's neck. "Come here." And then he kissed him.

Sherlock's mouth tasted sweet, like his afternoon tea, with a hint of chocolate from the three biscuits John had managed to get him to eat. He didn't respond immediately, but John pressed harder and eventually Sherlock made a tiny sound of surrender and his lips softened. John immediately took advantage, exploring the inside of Sherlock's mouth with his tongue and drawing a longer groan out from the detective.

When he finally drew back, Sherlock was a bit flushed and breathing heavily. "Perfect," John declared. Sherlock looked dazed but perfectly alert - the ideal combination for the evening. "I'm going to give you some rules for tonight, and you're not going to argue with me."

Sherlock blinked.

"First rule is, you're going to address me as 'Sir.' No exceptions. It's something I require of anyone I play with here, and everyone will expect it."

Sherlock licked his lips. "Yes . . . sir."

Oh, God, the sound of it in Sherlock's deep baritone was already sending shivers down John's spine. He allowed himself only a second to indulge, though, before pulling up to his full height and reverting to his dom stance. "Second rule: when I'm at your side, you will not speak unless I ask you a direct question. The only exceptions are safewords and when you're . . . thirsty." He looked Sherlock directly in the eye to underscore their agreement from back at the flat. "If you should find yourself apart from me at any point during the evening, you may speak when spoken to, but always respectfully. And always defer any decisions to me."

Sherlock swallowed, but he kept his eyes on John. "Yes sir," he said again.

"Third rule: you will speak up if I'm making you do something you're not comfortable with." John grabbed Sherlock's hand and squeezed to underscore the point. "Usually I insist on step-by-step consent with new subs, but we're going to have to pretend we already play together, so we don't have that option here. And I don't give a flying rat fuck about the case, if it means accidentally pushing you into something you're going to have issues about later. So I'm going to be assuming consent unless told otherwise."

"That's . . . reasonable." Sherlock nodded, not breaking the intense eye contact John was forcing on him. He licked his lips. "I trust you," he whispered. "Sir."

"Good." John stepped back and smiled. And yes, Sherlock was responding properly, taking a little breath in confusion at the sudden extra space around his body. John crouched down to rummage in his duffel bag and pull out a short length of his thinnest rope. "Hold still - this is going to make everything easier."

Sherlock raised an eyebrow, but didn't comment. Even when John started lacing one end around his waist, weaving it in and out through base of the fishnet shirt. John tied one end off in a slipknot, then took the rest of the rope and wrapped it around his hand. The effect was a loose leash with which he could throw Sherlock off-balance whenever he wanted, but which wouldn't twist the shirt unnecessarily. He glanced up at Sherlock's face, half-anticipating resistance, but Sherlock merely looked intrigued.

"Right then. Ready to meet everyone?" John gave a slight tug - eliciting a tiny indrawn breath from Sherlock - and led him inside.