At the end of Portal, when you are fighting GLaDOS(big computer lady) her various AI cores each hold aspects of her personality. The first one, which is purple, although has no dialogue, is apparently morality. The second orange one seems to be curiosity, because it drills you with questions such as "Where are we. Who are you, where are you going?, etc." The third one seems to be cake making. It says things about flavors and garnishes. The fourth and final red one seems to be viciousness, screaming wildy and twitching uncontrollably. Very interesting, neh?

I couldn't help but burst out laughing when the curiosity one asked 'do you smell something burning?' when I dumped it into the furnace.

One of the funniest moments of the game for me there.