Bill: Well plenty of people come to your lectures that aren’t supposed to. Why pick on me?
The Doctor: Well I noticed you.
Bill: Yeah, but why?
The Doctor: Well most people when they don’t understand something they frown. You… smile.
The Doctor: That’s my face, yeah?
Bill: I see you’re a bit flexible on the subject.
The Doctor: Oh, you have no idea.
The Doctor: I’ll tell you what. Let’s just pop into my box.
Bill: Your box? What good is getting in a box going to do?
The Doctor: What an extraordinarily long and involved answer this is going to be.
Bill: So your box can move. It can go anywhere it likes?
Nardole: Mm. Good, innit?
Bill: Anywhere at all in the whole university?
The Doctor: Is it my imagination, or is this taking longer than normal?
Bill: Are you from space?
The Doctor: No, of course not. Nobody’s from space. I’m from a planet like everybody else.
Bill: This planet?
The Doctor: No, not specifically this one.
Nardole: So how do we know this water thing is actually dangerous?
The Doctor: Ah, because most things are.
Nardole: Hm. That’s true.
Bill: Why? Is everything out here evil?
The Doctor: Hardly anything is evil. But most things are hungry. Hungry looks very like evil from the wrong end of the cutlery. Or do you think your bacon sandwich loves you back?
Bill: I’m not stupid you know. That’s the trouble with you, you don’t think anyone’s ever seen a movie. I know what a mind wipe looks like!
The Doctor: I have no choice. I’m here for a reason. I am in disguise. I have promises to keep. No one can know about me.
Bill: This is the most exciting thing that’s ever happened in my life. The only exciting thing!
The Doctor: I’m sorry.
The Doctor after the TARDIS chimes in: Will you all please just leave me alone. I can’t do that anymore. I promised!
The Doctor: It’s a big universe. And maybe one day we’ll find her.
Bill: What changed your mind?
The Doctor: Time.
Bill: Time?
The Doctor: And Relative Dimension in Space. It means, “What the hell.”