A bird may love a fish but where would they build a home together?
This is a quote from Fiddler on the Roof. The father of the Jewish family is talking to his daughter who has fallen in love with a Christian. She wants to break tradition and marry outside of her faith.
When Rowena called Cas a fish that wants to fly, all I could think about was this old proverb. It has such… romantic connotations. Castiel has always been the fish out of water. And this is another reference to him being not quite angel and not quite human and needing to make a decision as to which of those he wants to be. Everyone this season has been telling Cas that he isn’t a regular angel and can never be happy with that life. He is a fish who wants to fly. It feels to me like this is yet more foreshadowing that he will choose humanity [a-hem Dean] and choose to give up his grace to do so.