- Sam: Well, I found this. Hidden in their library. It's ancient. Written by a priest who went dark side. There's a binding spell in here for trapping a reaper.
- Sam: I mean, he must have had some kind of reason for saying it, right? Did he know the demon's plans for me? Am I supposed to go dark side or something? What else did he say, Dean?
- Ruby: Now's not the time to bellyache about Sam going dark side. He does his thing, he exorcises that demon, or we die.
- Sam: You think I'll do it, don't you? You think I'll go dark side.
- Sam: So we tell him the truth. You say Jesse's destined to go dark side — fine. But he hasn't yet. So if we lay it all out for him — what he is, the Apocalypse, everything—he might make the right choice.
- Bobby: But if we ain't... If there's a snowball of a snowball's chance here...that means we're dealing with a Superman who's gone dark side. Which means we've got to be cautious, we got to be smart, and maybe stock up on some Kryptonite.
- Castiel: Superman going to the dark side. I'm still just Castiel.
- Dean: If I do go dark side, you got to take me out.
- Dean: Yeah. Hey, if Cain found a way to live with it after going dark side, then I just got to find a way to keep it in check, so haven't had a drink in a week, eight hours of rack time every night, and... now this masterpiece.
- Dean: How's the kid, he go dark side yet?
- Sam: Nope.
- Mary: Dean, like it or not, Lucifer is Jack's father. He's going to take an interest in him.
- Dean: So, what, we're supposed to just let Lucifer drag him over to the dark side?
- Mary: Jack isn't going to the dark side. He'll see Lucifer's true nature. And he'll see through his own eyes, not yours.