Archangel's heir

Castiel is an archangel, very old, wise, but arrogant and possessive with a cold heart. He is on the Earth now on a mission because a lot of angels disappeared and he is trying to find lut what happened sith them. You are a younger demon woman and you are also on the Eart, trying to find any evidence why a lot of demons are missing and they are not coming back. One night both of you are in an abandoned warehouse when both of you get hit from the back and become unconcious.