(Or alternatively, the angelical equivalent of a direwolf, but still a puppy all the same)
He gives unconditional love and just wants to please those he cares about. Everything he's done, he's done for Dean, because of Dean. While with current circumstances has forced him to make certain questionable and regrettable decisions, he is still fiercely loyal and protective of his humans, as it's ever-so present throughout 6.20. And when they are mean to him, he gives them that sad look on his face like a puppy does when you're scolding them. Even when they shut him out he comes back, wanting so desperately for his human to understand him.
WHY WON'T SOMEONE GIVE HIM A HUG ALREADY? JFC. :(
BTW, everyone needs to check out alexwhitman25's Dean/Castiel 6.20 picspam since it really demonstrates so vividly how this episode was truly such a heartbreaking love story between those two. Creys, you'll have them. Hell, even if you don't watch Supernatural you should see this picspam, just to see why I love how beautifully angsty these two are. ♥