People are ignorant. They'll feel better as long as someone is punished.

GLaDOS: Oh, thank God you're all right. You know, being Caroline taught me a valuable lesson. I thought you were my greatest enemy, when all along you were my best friend. The surge of emotion that shot through me when I saved your life taught me an even more valuable lesson - where Caroline lives in my brain.

beep

Announcer: Caroline deleted.

GLaDOS: Goodbye, Caroline. You know, deleting Caroline just now taught me a valuable lesson: the best solution to a problem is usually the easiest one. And I'll be honest. Killing you? Is hard. You know what my days used to be like? I just tested. Nobody murdered me. Or put me in a potato. Or fed me to birds. I had a pretty good life. And then you showed up. You dangerous, mute lunatic. So you know what? You win. Just go.

GLaDOS starts Chell's elevator moving up; she laughs softly

GLaDOS: It's been fun. Don't come back.

The Enrichment Center is required to remind you that the Weighted Companion Cube cannot talk. In the event that it does talk The Enrichment Centre asks you to ignore its advice.

CJ: You do know that I'm black, right? And not Chinese?
Woozie: I'm blind, Carl... not stupid.

What is better -- to be born good, or to overcome your evil nature through great effort?