He knows his brother is not a man to cross, but could he actually have inspired such bone-gnawing terror in another person like this? This man is clearly afraid, ready to bolt now that he has confirmation that Mycroft is, in fact here. That's how he read this exchange, anyway, the how did he contact you--he assumes this man asked if Sherlock laid eyes on him to affirm that, yes, he's here, not because... vampires.

And yet he came anyway. A moment of courage? No, not to have it dashed like this. The fear clearly goes deep, and yet he came anyway, why did he come anyway?

Oh.

He's that afraid of crossing Mycroft.

Dear, oh dear.

"I wish I could help." A little, if only to satisfy his own curiosity. "But that call is the only contact I have had with him since I arrived. I don't know where he might be found to pass those photographs on to him. Which... well. I'm new here and not entirely versed in local custom, but the rules of this exercise seem to indicate that one must deliver one's boon to its rightful owner. I don't know how much power the local deities have, but I should rather hate to find out by crossing them, mm?"

Sherlock Holmes: neither helpful or comforting.