Kevin was learning a lot of new things when they first met that it probably would've gone right over his head, but it's interesting hearing about it now. The lives that Sam and Dean lead are kind of mindboggling to him, that Sam needed Cas to take on hell damage. What a concept. And what would Kevin have done, if he could go back, when the trials failed and Kevin had slightly more of a choice? He could've walked out and invented a new life for himself. What would that have even looked like?

"Probably more time than this is going to take." It's a weak attempt to help console him; it doesn't change the fact that Cas is dying miserably right now, after all, no matter how long it is or isn't going to take for him to get better.

"You'll be back to normal soon enough."