Talking to Ruby about it is something he will have to consider. Of course, he'll get there eventually because they're the only two non-humans he is aware of.

These conversations are often unnecessarily complicated and labyrinth-like. Would he change that about his friend though? No. Cas can only assume his 'rocks' go hand in hand about his humanity. "Yes. The connection with Heaven here is weaker. In time, I will probably lose all my grace and be... human." He hadn't wanted to trouble Dean with that theory before, but now he does not sound so sure that it is a bad thing. There's so much more to humanity than burning brightly for a short amount of time in his opinion.

Whichever way it goes, Castiel can only be better for his experiences with Lucy.