The disguise is a poor one; Watson sees through it within seconds. This means, of course, that Holmes intended for him to see through it, because Holmes is never sloppy by accident. It is, Watson supposes, enough to fool anyone who might be passing by on the street, but to someone who has spent years sharing lodgings (and more) with Holmes, there are several telltale signs—his way of holding his shoulders, a certain twist to his mouth—that give the game away.
Watson sighs when he sees him, and returns his attention to the notes he's been making about Colonel Beckwith's dropsy, because he'll be damned if he'll reward Holmes' little act by watching as Holmes removes the costume of a feeble old man. He ignores the part of himself that is actually glad to see Holmes walk in this way; that's all in his past now.
"Well?" Holmes is annoyed by Watson's lack of attention; that much is clear.
"Really, Holmes. Couldn't you have just sent a note informing me that you were going to call?" Watson asks, not raising his eyes from his paperwork.
"Why in the world would I do that?"
"It would be polite."
"And what are manners between old friends?"
Watson finally looks up at him. "Why are you here, Holmes?" he asks. "If you want me to accompany you on a case, I'm afraid I can't—"
"I came because I'm worried about you, Watson," says Holmes, with exaggerated insincerity. "And from the look of things, I'm quite right to be."
"What is that supposed to mean?" Watson mentally kicks himself for sounding more frustrated than bored, but there's no helping that now.
"Just look at you, old chap!" Holmes exclaims. "Only six weeks married and already working late, though you haven't any patients who require your attention. This is hardly the picture of domestic felicity you painted for me before you vacated our rooms at Baker Street."
Watson clenches his teeth and says nothing, because he refuses to let Holmes goad him like this. He's only in his office because Mary is attending a meeting of her Ladies' Charity Association, and Watson knows that Holmes must know this, and besides, the state of his marriage (which was just fine until a minute ago) is none of Holmes' business, thank you very much.
"Ah. Touched a nerve, I see."
At that, Watson stands and slams his hands down on his desk in front of him. "I cannot have this, Holmes!" he says. "You can't just walk in here unannounced and expect me to—"
"Expect me to what?"
Watson draws in a sharp breath, because he knows exactly what he was about to say just now, and he's actually relieved that Holmes interrupted him. "You must leave, Holmes. If you wish to see me, you can arrange an appointment, like an ordinary person."
Something flickers in Holmes' eyes then, and Watson isn't sure if Holmes is actually hurt or if he's just play-acting. Whatever it is, it's enough to make Watson soften his tone. It's not as though he wants to cease all contact with his old friend, after all.
"Listen, Holmes," he says, making his way around the desk. "Why don't we meet for lunch at the Royale on Saturday?"
Holmes frowns at him. "You'll bring Mary," he says in the tone of a petulant child.
"Is that a problem?" asks Watson, even though he already knows the answer.
"Yes," says Holmes. "I'm very much afraid that it is."
And then, before Watson has time to recognise Holmes' intentions, he finds himself pressed hard against his bookcase with Holmes' lips hot against his own.
"You see," Holmes continues, not breaking contact, "if Mary's there, we can't do this."
Watson wants to point out that they can't do this in the middle of the Royale anyway (which is half the reason he suggested it), but he can't; he can't because Holmes' mouth tastes like coffee and tobacco, just as Watson remembers it, and because Holmes is doing that thing with his tongue, where he teases Watson's upper lip just so, and Mary hasn't learned how to do that yet (and maybe Watson hasn't wanted to teach her; it's not right to think of Holmes when he's with her, it's not). This is safe and familiar and dangerous and exhilarating all at once, and Watson surrenders himself to it. When Holmes works one of his hands between them, placing his palm over the distended front of Watson's trousers, there is only one word on Watson's lips:
Holmes wastes no time in dropping to his knees and Watson can't help but shudder as he feels Holmes unbutton the flies on his trousers and his drawers. That's nothing, however, to the cry that escapes Watson's lips as Holmes takes him into his mouth. Watson hands grip the shelves behind him tightly; he feels sure that his knuckles must be turning white. The warm, wet heat of Holmes' tongue on the underside of his shaft, the way he moves his head with the rhythm of a musician, in perfect counterpoint to the way that Watson thrusts against him.
Watson's missed this, and he hates that he's missed it, that he's given into it, but they're too far gone to stop now. He yells when he reaches his climax, and he trembles as he feels his seed spilling into Holmes' mouth.
When Holmes pulls back from him, he's wearing a satisfied smirk, and Watson knows that if he wasn't still overcome with the warm afterglow of his release, he would want to punch the man, because he'd sworn to himself that they wouldn't do this again, and Holmes knows that. But at this moment, he's too sated for anger, so when Holmes stands, Watson doesn't find it difficult to draw him in close again, to press their mouths together so he can taste himself on Holmes' tongue.
His hands make their way to Holmes' trousers as though by instinct; he undoes them deftly, and it only take a few well-practised strokes before Holmes finds his own release in Watson's hand. His hands are tight on Watson's shoulders, and for a moment they look each other directly in the eye, and Watson thinks that Holmes is saying, This is how it should be.
It takes an effort to break from Holmes' gaze, but Watson finally manages it. He finds a handkerchief in his waistcoat pocket and Holmes steps away from him, leaving a cold space between them. Watson turns towards the bookshelf as he tidies himself and refastens his clothing; he can hear Holmes moving behind him, and when he turns back towards his office, he sees that his friend has resumed his disguise.
"Mary deserves better than this," Watson finds himself saying. "I want to give her better than this." Mary is smart and brave and loyal, and everything that Watson always told himself he wanted in a woman. Everything he was supposed to want.
For a moment, Holmes almost appears to be regretful. "I know, old boy," he says. "I know."
"This mustn't happen again," Watson says.
"If that's what you wish," Holmes replies. "If you really wish it."
Watson thinks that it's best not to reply to that, and Holmes turns away, making his way to the door. When his hand touches the doorknob, however, he turns to face Watson again.
"By the way," he says, with a definite glint in his eye, "a hansom cab will be waiting out front of your house at eight o'clock tomorrow morning. Do try not to be late."
"What?" Watson feels himself spluttering.
"Oh, didn't I tell you? I'm investigating a most singular case at the moment, and I know you won't want to miss out on it. You'd better bring your service revolver."
Holmes is out the door before Watson has the chance to respond, and Watson finds himself cursing loudly with no one to hear him.
"I won't do it," he mutters. "I won't."
But even as he speaks, he's beginning to compose a letter to Dr. Firth next door, asking him if he'll take tomorrow's patients, because some urgent business has come up.
I'm sorry, Mary, Watson thinks. He can't quite bring himself to admit that part of him isn't sorry at all.