Dark Water

DOCTOR: You betrayed me. Betrayed my trust, you betrayed our friendship, you betrayed everything that I've ever stood for. You let me down!

CLARA: Then why are you helping me?

DOCTOR: Why? Do you think I care for you so little that betraying me would make a difference?

MISSY: (as Maggie Smith) I am in charge.

DOCTOR: Well, who's in charge of you?

MISSY: I'm in charge of me.

DOCTOR: Well, who repairs you? Who, who maintains you?

MISSY: I am programmed for self-repair. I am maintained by my heart.

(Missy takes the Doctor's hand and places it on her bosom.)

MISSY: Is everything in order?

DOCTOR: Who maintains your heart?

MISSY: My heart is maintained by the Doctor.

MISSY: Hello. I hope you're well. How may I assist you with your death?

DOCTOR: Well, there is, er, no immediate hurry. We're just, er. We're just...

CLARA: Browsing.

DOCTOR: Yeah, yeah, browsing.

MISSY: Please, take all the time you need. At 3W, you always have the rest of your life.

DOCTOR: Who maintains your heart?

MISSY: My heart is maintained by the Doctor.

DOCTOR: Doctor who?