Don't hesitate of you want to make changes on how the cover colors are used. Long as the theme remains good vs evil. If splitting the cover black & white doesn't work for you feel free to chance to what works best. The male characters should show a muscular appearance. The girl athletic. The angelic figure should be blond headed, tan, with a light aura around him. The wings feathery draped down to the sides not extended. The demonic figure should be dark headed, go-tee, his wings should be leathery like skin over bone and pulled down, not extended with a dark aura around him.