[He is very hurt that Stiles apparently disapproves of all his work efforts, kk. Tada, one cave guide popping his head in.]
There you are, Mr Stilinski. [He almost thought you'd been eaten by something. Is Sebastian on a rescue mission? Nah, his tone has that hint of mild surprise to it that basically adds "fancy running into you here".
...Then he smiles.] Oh, and you have made a friend. [It's funny because Stiles doesn't look thrilled.]