I assume that angels and demons don't interact regularly so how did learn that you could get along with them? How did you get your position after that? Did you offer your skills or were they discovered?
----
Ooh his parents, ok so first of all he doesn't actually have a dad (he thinks he does), his demos mom is just a skilled magic user which allowed her and his human mom to have a kid. As for how they met, well the town his human mom grew up in was very close to the border between the middle country and the demos country. His demos mom basically got into a fight with her family so left angrily and hid, disguised, in a human village where she met his human mother, they fell in love, and the whole shebang happened.
As for the heart mark, that's part of world lore stuff that I haven't written up yet, but basically magic users fall into 4 categories, diamonds, hearts, spades, and clubs, and they have a symbol which represents what magic they can do. Ravios is a heart so he gets stuff like mind-control/reading magic. Influencing people. Whatnot like that.