Liza, a muggle-born witch, wasn't one that was very well liked. She knew something was wrong with herself, and so did her muggle parents. They sent her to a mental hospital. From there, she was turned away due to the strange things that happened around her. When angered, a syringe would go flying through the air and would hit the opposite wall. Or maybe a tray of food that was just sitting there would magically float and hit someone in the face.
Either way, they sent her back to her parents.
Her parents weren't happy at her return. She was hurt for the first week after her return home. However, by the next time it happened, a pair of scissors went flying and landed in her father's shoulder. He yelled in pain and her mother called her a witch, which true at the time, hurt the girl.
Her parents were found unable to raise the child and she was removed from there and given to heraunt, who, ironically, was just like Liza. Liza sound found her home as her aunt understood her. However, unlike her aunt, Liza got the chance to go to Hogwarts. Her aunt was told by her mother to never exploit her powers, and she never did.
Once at the age of 11, the letter from Hogwarts arrived with a beautiful brown barn owl. The owl flew away as she picked up the letter and read it. Liza finally had the answer to her problem, it was just because she was a witch, a real one, not a name she was called!
She showed the letter to her aunt who gladly agreed to let her show her magic. However, since her aunt was uncapable of taking her to take care of all her needs, the grounds keeper, Hagrid, who magically was still alive at the time, took her around to Diagon Alley. From then on most of school was smooth sailing. Well... for the first two years, any way.
Around her third year, it slipped that she was a Muggle-born witch. A lot of the kids used to bully her. It got to the point where she ran into the girls bathroom and considered cutting herself. That is, until a 1st year girl came in. She was from Ravenclaw and the two quickly became friends.
From there, kids learned that Liza was a powerful witch, capable of things they wish they could do. They backed off of her and she grew into the girl she is now.
During her 5th year, she became a prefect. Also, around this time, she was asked to be part of the group of Witches and Wizards who protect Hogwarts from weird things. Among the people she were to protect were Jinx and Wes, two people with bonds in Azkaban.
So, Liza made it her job to know the two. Jinx became one of her best friends and lets just say, Wes and her grew a very special bond.
In year six, she continued her job as a prefect along with carrying out her jobs in the Wikia Order of Witches and Wizards. She kept her ties in the school as well as keeping her grades up. Because of this, she was offered the job as Head Girl.