Game of Thrones, Season 2

Cersei Lannister:
I heard a song once, about a boy of modest means, found his way in the home of a very prominent family. He loved the eldest daughter. Sadly, she had eyes for another.

Petyr Baelish:
When boys and girls live in the same home, awkward situations can arise. Sometimes, I've heard, even brothers and sisters develop certain affections. And when those affections become common knowledge, well that is an awkward situation indeed, especially in a prominent family. Prominent families often forget a simple truth I found.

Cersei Lannister:
And which truth is that?

Petyr Baelish:
Knowledge is power.

[Cersei pauses a moment]

Cersei Lannister:
[to her guards] Cut his throat. [her guards move to do so]

Cersei Lannister:
No, wait. [chuckles] I've changed my mind. Let him go. [her guards do so] Step back three paces. [they obey]. Turn around. [they obey] Close your eyes. [they obey].

Cersei Lannister:
[steps up to Petyr] Power is power.