Dean: She knows what your weakness is. It's me!
Trickster: Dean's your weakness. The bad guys know it too.
I think this is interesting. Twice Dean has been referred to as Sam's weakness. It's interesting to think about the demons using Dean (through torture or by death) as a way to break Sam down and get him where they want him. It's interesting to think about Dean being what stands between Sam and...that.
Also in Mystery Spot, the Trickster, as Bobby, said something interesting to Sam during the time Dean was "really" dead. I can't find an exact quote anywhere but it was something to the effect of...he hoped Sam wasn't sitting there in a motel room obsessing about Dean's death, that no one man should take on that responsibility by himself.
I REALLY wish I could find the exact quote because it just struck me the second I heard it tonight. He didn't say Sam shouldn't obsess about it or try to fix it, he said Sam shouldn't be trying to do it ALONE.
It made me think that maybe he was trying to put it into Sam's head that he needs help. Say...from demons? Say...by giving them something they want?
For the record, this is all PURE speculation, no spoilers. Just quotes that stuck in my head and made me think. I don't know! But it is interesting to think about...
ETA: crazywritinfool had the quote: "No one man should take something like this on alone."