Simple opinoin question (see Details)?

okay so for my story im writing from the pov of a guardian angel and she goes down to earth as a human to help the girl that she is igned to even though it is against the "rules" and ends up falling in love wit her brother. my question is should I focus on her helping the girl or make it into more action and balance that with a mixture of a "satan" figure trying to destroy her/ stop her from keeping the girl alive? what do you think? I am afraid if I mix it with the action it might become like a twilight sort of thing which I def DO NOT want! opinions plz!!!!