II.
The hall is large and, when they arrived, John couldn't resist raising his voice a little to see how it echoed. It's filled with people now, though, and any echoes there might once have been are muffled by the press of well-dressed bodies. Frankly, Lestrade can't believe Sherlock's agreed to take this case for Mycroft at all; it's only a little less incredible that he and John have had to come along, dressed in tight, scratchy evening wear that only sort of fits.
Sherlock is prowling the perimeter of the room; his evening wear is tailored, of course. Lestrade and John have already finished grumbling about that and have moved on to wondering exactly why they've had to come.
"I need backup. Obviously," says Sherlock, coming up behind them.
"Sherlock, you've never admitted to needing backup in your life," John points out and finds himself on the receiving end of a black look.
"Not for the case," the detective elucidates. "For Mycroft."
Lestrade grins. "Never run interference for the Holmes brothers before, John? It's a question of keeping Sherlock as far away from Mycroft as humanly possible while convincing Mycroft you're doing your damnedest to get Sherlock to talk to him."
Sherlock smirks and wanders away, and Lestrade adds under his breath, "… and then 'accidentally' bringing Mycroft his brother if it really is important."
"Or if Sherlock gets particularly irritating?"
"I thought you said you hadn't done this before."
In the end, Mycroft saves them both the trouble by catching Sherlock on his second lap of the room and pointing out that a group of three men, standing at the sidelines instead of dancing despite a surfeit of partnerless women, draws rather a lot of attention, considering they're trying to be undercover. Then he leaves Anthea (no, it's not her name, but John and Lestrade have found it works as well as any other) with them and gives his brother one last, hard look before he moves along.
"I am not," Sherlock tells her, "going out there and… dancing."
Anthea smiles apologetically at him. "I'm afraid that isn't what your brother said."
"Yes, well, my brother doesn't know everything, much as he would like to believe he does."
She keeps on smiling, tinged with pity.
"Oh, get on with it, Sherlock," says John. "Lestrade and I can keep an eye on the perimeter." At Sherlock's derisive snort, he points out, "A detective and a soldier? You could do worse."
They all stand there for a minute at an impasse, Sherlock motionless with his hands at his sides, Anthea frozen in a sort of half-shrug.
Finally, Sherlock grits out, "Mycroft is doing this on purpose."
"What, making you dance with a gorgeous woman?" John asks. "Whatever it is he's doing to you, d'you think we could get him to do it to me instead?"
Anthea's eyes flicker to him and he grins ruefully. "Yeah, I didn't think so."
The hands that have been hanging loosely curl into tense fists. "Mycroft is well aware," says Sherlock, "that I refused to participate in my mother's attempts to bring me into polite society."
"Don't know if polite society would have him," Lestrade mutters to John.
"Sherlock," asks John, "are you saying what I think you're saying?"
Arching an eyebrow, Sherlock points out that, without further information, that is rather difficult to determine.
"Are you saying that you – " John's going to savour this moment – "can't dance?"
"I never found it worth my time," the detective snaps.
Lestrade bites his tongue and manages not to point out that this time, the knowledge Sherlock hasn't bothered to acquire could actually have helped him with a case, so his usual argument won't work.
Instead, he offers an arm to Anthea.
She looks at him. Mycroft did say that Sherlock was to dance – but then again, Sherlock says he can't, and the DI is awfully good-looking.
Sherlock gives him a look. "You?"
"Shut up."
"Well, someone had better," John cuts in. "We're getting loads of strange looks, and wasn't the point of all this to avoid that?"
"Right," says Lestrade, and he wraps the arm around Anthea's waist. "For the sake of the case."
"Right," she echoes vaguely, and they're off.
It turns out that Lestrade has been rather less than forthcoming about this particular skill of his, and even Sherlock looks briefly impressed, before he hides the expression behind a much more characteristic scowl.
John shrugs – they can't blame him for not dancing; he's a war veteran and he can still conjure up a fairly effective limp when necessary – and strikes up a conversation with a young lady nearby. That ought to look unsuspicious enough, and she is, after all, quite lovely.
Sherlock has never thought before that he would regret his decision to abnegate his mother's ballroom dance classes, but now he's realized exactly where his lack of dancing skill has left him.
Alone at the side of the ballroom floor.
With Mycroft.