After the event's of The Fall (**SPN-Season 8 Finale***)
Castiel has become a hunter but he is still plagued with what his actions caused. His pain, his guilt causes the now human Cas to turn to alcoholism and weed for comfort; for the numbing effects. It numbs his emotions and pain, years ago Castiel had spoke to Dean to help him. Now Dean echoed it back to the fallen angel.
"You can't save everyone Cas, though you try you just can't. You did your damndest to fix everything!"
Though the words rang true Castiel still couldn't forgive himself, his eyes remained downcast and glossed over from the shame and left of weed left in his system.
"Dean...I...what I've done...can't be fixed.."
Dean sighs " You don't need to fix anything! You did what you thought was best! It was that damn Metatron who tricked you! Hell, he fooled all of us!"
There was nothing but silence from Castiel as memories of his fellow brothers and sister falling flashed in his minds eye. Dean took Castiel's hand in his own
"Cas...I'm still here for whatever that's worth, alright."