Ianto watches, partially amazed as this strange man burst into the cafe, then out, then back in again, seeming to under some sort of manic impulse. He's clearly not a stranger here, although he's a stranger to Ianto. He's surprised to be directly addressed by someone he doesn't know, especially in such a direct way.
His expression shifts as the man introduces himself as the Doctor, though. He, the one before, had talked about regenerations, and there were mentions in Torchwood records of men of varying appearance going by the same title. It's jarring, but not more than he can handle.
He waits for him to settle down, this version of him apparently on some sort of permanent caffeine buzz, then walks over to him, expression neutral, voice cool. "I think we have a lot to catch up on indeed, Doctor."