It's true that Mayland Long can make himself more inconspicuous than most, merely by the fact of his not trying. Someone attempting to sneak is more often than not furtive--Sherlock's mind is attuned to little motions out of place, noise in silence, silence where there ought to be ambient noise. Long, on the other hand, just insinuates himself into crowds. And Sherlock absorbs himself utterly into what he's doing, when it takes his interest, which Paganini certainly does. As capable as he is of broad and meticulous observation, when he fixes himself on a point he's also capable of massive oversight.

As recent events have borne out.

Sherlock starts a little at the greeting. It surprises him more than the others he's received today, maybe because Long has never come to see him play before. At least he approves of the music--Sherlock is fairly certain he would know if Long disapproved of the music. He's a tolerant old dragon, but he has less tolerance than most for bad taste. Something they have in common.

"Yes," he answers after a moment. "I suppose I have."

He sets his bow aside but keeps hold of the instrument by the neck for the time being. It has not failed to occur to him that, excepting exactly one set of clothing, his violin is the only tangible object that has any chance of being real and from his world. The corpus carries microscopic blemishes where others' fingers have touched it--perhaps imperceptible damage to the varnish on the waist in the shape of the pads of John Watson's fingers from the time or two he's handled it without Sherlock's permission. The dust on it is gone from routine cleaning: the accrued detritus of a London flat, wiped away the first time Sherlock took a chamois to the instrument in Taxon. The coat and scarf will wear out with time. Little by little, he loses the pieces.

"Fortunately," for ceremony's sake he checks the watch on his tablet, "I don't particularly work on a schedule. I am at your disposal, Mr. Long."