Arabella grew up on an orphanage on San Fran, never knowing who her parents were. She was always sad since everyone got adopted apart from herself. When she turned 13 she knew her dim hopes of being adopted were gone since people only wanted 'cute young kids'. She didn't leave since her best friend was also there and she had a ceiling above her head and food without having to work.
When she turned sixteen though, her friend was adopted. She was depressed over the fact that even a 15 year old girl was adopted but she wasn't and ran away from the orphanage. After a week running away from the city, she found the Wolf House.
Lupa smelled the legacy on her and trained her, but didn't reveal anything about her parents. After a month training, Lupa said she was ready and gave her the directions to Camp. Bella was surprised when she saw that the entrance to Camp was so near her old home, the orphanage. She knew it was best to go to Camp fast, but she wanted to see her old 'sisters', the little orphan girls she helped taking care of.
But when she got there, a woman was asking for her on the front desk. The old lady that ran the place pointed to Bella and said she was the girl the woman was looking for.
The woman smiled and asked if she wanted to come with her to a new home. Bella said no, thank you and the woman got mad. She turned into something that resembled a huge chicken and attacked Bella.
Bella tried to hit her with a knife she had stolen from a supermarket on her way there, but it didn't do anything. She ran out of the orphanage and to the Camp entrance, hoping to lose the chicken-woman on the way. No such luck, the harpy followed her.
When Bella got near the tunnel, she screamed for someone to shoot down the chicken, but the kids watching the entrance only figured out what she said when they saw the harpy flying towards them. One of them, a son of Apollo, thought quickly and shot it down. They took her to Camp and introduced her to the praetorm who let her in and put her on probatio. She soon found out that she was the daughter of a son of Bellona that once came to Camp, but left after he turned 21 and they never heard of him anymore.
She's sadistic and can be a real b*tch to people she doesn't like. She's mistrustful of everyone and proud of herself, even if she still doesn't know anything about her family apart from vague things she heard about her father