A Quote from Portal 2
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.
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.