Castiel's eyes were dark, unreadable, and Dean was left to wonder if Castiel wanted this as much, needed this as badly; to wonder if he needed more, whether Castiel could give it.

Oh, honey, you have no idea.

This is what breaks my heart about them: how even when Dean can't believe in anything, when he's not capable of doing anything but throwing himself away, Cas is right there, trying to shore him up.