Angels' mission (Castiel x Angel OC)

Cathren Angela Summers is a 25 year old Demon hunter.
Or is she really something else?
Cathren fell from heaven centuries ago, she fell because she was in love with Castiel (Not like Anna, she keeps her Grace...but she hides it). She is on a hunt, she cannot die, and she meets the Winchester brothers......and later Castiel.
After hunting with the brothers for a week they get into some serious trouble, in front of all three she does something stupidly heroic. Castiel gets a glimpse of who and what Cathren really is, he gets a glimpse of her Grace.....which flows through all Angels. Will Castiel feel for her what she feels for him?

I don't own Supernatural. I do own Cathren and most of the plot.