... I've never been here before.
[If this is someone he's met before, he should recognize him, right? It's confusing that he doesn't, and it leaves him wary.]
Who are you?
Other options:
no subject
... I've never been here before.
[If this is someone he's met before, he should recognize him, right? It's confusing that he doesn't, and it leaves him wary.]
Who are you?