Ask the weird man who he is
From Create Your Own Story
You: Excuse me, sir, but may I ask who you are before I go running off with you?
The unusual man pauses and seems to internally punish himself for being so silly as to forget to introduce himself. Waving his hand with a flourish, he answers your question.
Strange Man: Oh, allow me to introduce myself. I am the Doctor. Well, people call me the Doctor. I don't know why... I call me the Doctor, too! I still don't know why...
The Doctor pauses to consider this for a moment before bringing his eyes to meet yours once again.
The Doctor: Well, there really is no time for introductions, we have to run!
You rather like this "Doctor." You decide to...