The Doctor and Idris in “The Doctor's Wife”

I don't understand. Who are you?

I'm the— Oh, what do you call me? We travel. I go... [makes the TARDIS materialisation noise].

[disbelieving] The TARDIS?

Time And Relative Dimension In Space. Yes, that's it. Names are funny. It's me. I'm the TARDIS.

No, you're not! You're a bitey mad lady! The TARDIS is up and downy stuff in a big blue box!

Yes, that's me: a Type 40 TARDIS. I was already a museum piece when you were young, and the first time you touched my console, you said—

[interrupting] I said you were the most beautiful thing I had ever known.

Then you stole me. And I stole you.

I borrowed you.

Borrowing implies the eventual intention to return the thing that was taken. What makes you think I would ever give you back?

You're the TARDIS?

Yes.

My TARDIS?!

My Doctor! Oh... We have now reached the point of the conversation where you open the lock. [The Doctor unlocks the cage with his Sonic Screwdriver. Idris steps out in front of him] Are all people like this?

Like what?

So much bigger on the inside. I'm... Oh, what is that word?! It's so... big! So complicated. It's so sad...