But dying is dying. Maybe being a ghost would be easier, but Dean can't just risk letting Cas pass away when this is Wonderland's work and anything could happen. What if the angel doesn't come back as a ghost, what if instead something goes wrong, and-- he just can't risk it.

"So what? I should help him die? That's messed up, Kevin." Even for a ghost expert like him. "Not like I would've let you die either."

Here. Or back home. He still can't believe that's all there's in store for Kevin. It seems so unfair. But then, aren't most things.