User blog comment:ImperiexSeed/Castiel's shifting of Sam's mental problems made no sense!/@comment-2020973-20120402015229

I don't think he erased Sam's hell, so much as shifted the memories to his own mind. I also think that since Cas is an angel it is taking the trauma longer to affect him then it did sam. Plus Cas did have to redeem himself for turning on Sam and Dean and bringing in the leviathans.