I knew I wanted another carus to have a talk with Dean, and I'm a huge fan of Season 2 Meg, so I let her be demon!Meg only without so much evil :D

Talking with Sam might help Dean work through things, but having someone he looks up to, someone who is in the same boat as him, I thought it was perfect, though again, this is from Dean's POV, so he's taking what Meg says and working through it in his head in a way that might not be right.