That part near the end of “You Do It to Yourself” when Sherlock’s expression turns to one of concealed pain as he hurriedly leaves the room has always fascinated me. His tone when he says “Good show, Mr. O’Brien” isn’t all that different from other times he’s given someone a sincere (if awkward) pat on the back, but it’s also just such a strange thing to say—not insensitive, no, but not exactly heart-warming either. And he doesn’t even address Jun. With hindsight, you know he’s no doubt thinking of Irene, but I don’t believe he’s being self-pitying in this scene. What I think is that he sees in Mr. O’Brien a somewhat bumbling figure who, just this once, stepped up to the plate, even as Sherlock thinks he’s also “the ultimate sap.” Something about it doesn’t sit right with him though.
It doesn’t sit right with him because he resents the fact someone he looks down on is able to be with the one he loves. Especially the man who didn’t even really earn it, so to speak. And maybe also a little because he himself failed his love when he couldn’t protect her from being murdered, though of course there was no way he could have seen it coming. But still. For a moment, Sherlock was forced to see himself in another person. To Sherlock, his past self “comes across looking a little bit dim.”
