"What the fuck else would they do?" says Dean.
Sam's nose twitches as Spokane blows a tickle of hair across it. "Not like that. I just meant-- I wondered if they still had that kill drive, or food drive, or whatever. They're technically dead over there, right? So there's no reason to eat. No need to, anyway. Without that, what do they do?"
Dean stares hard at the red light before them. He says, "Did you run out of Sudoku or what? They kill things, Sam. They're monsters."
"I'm not saying they didn't, man. I was just wondering if maybe--maybe that's the difference between a monster and an animal. I've always figured it had something to do with survival instinct versus sadist instinct. Or something."
Dean considers this. "You mean like, all vampires want blood. But some of them are dicks about it. Which makes them monsters."
"Sure, I guess," Sam shrugs. "It's not a perfect taxonomy. Your average wendigo isn't an asshole. Just creepy."
"Still cannibalistic, though, which is kind of a dick move. On the other hand, hamsters eat each other all the time. Have you ever seen--"
"--Okay! Cool, Dean. I don't need to imagine R-rated Animal Planet right now."
"Hey, you started this."
They circle Spokane another time. A girl went missing in the mountains three days ago. Generally the way shapeshifters work is people come up double, not zero, but it might be worth a shot.
"Dean," Sam asks. "In Purgatory. What did you eat?"