Lucy comes from Hell. Her father is the big red guy himself. After achieving less than acceptable scores from her final exams, she was expelled from Hell School. Her father grounded her...literally. He took her big ole demon wings so she couldn't fly. This also led to some power restrictions and eventually a one way trip up throw the surface to the human world so she could attend human high school as a punishment. She is only allowed back in hell once she passes all her classes with Bs or higher. Otherwise she faces spending all of eternity alongside humans...and we all know how much we suck.
Personality-wise, Lucy gives no fucks. She has one goal and that's to graduate high school so she can go back home. She is nice to only a select handful of people, those include her two demon BFFs; Dia and B.B. Strangely enough, she is seen as the heroine of her school just because she stands up to bullies and mean girls. That's mostly because she deems herself to be the demon queen of the school and forbids anyone from picking on her loyal subjects.
Lucy's abilities, while said to be restricted, are quiet awesome to humans. She's got enhances stamina, strength, and speed as well as the ability to control fire, teleport, and use those cool alchemy circles you see in anime//SLAPPED// They each range for what they can do so that's for another time...when I know what all I want this character to be able to do.
She has to battle some angels just because they believe she's the anti-Christ come to purge the earth and cause rapture. They never listen to her when she says she isn't. Can't trust a demon.