Who is Ruby Miliken from One of Those Hideous Books Where the Mother Dies and what is their importance?

Ruby is a fifteen-year-old high school student with a sharp mind and sarcastic sense of humor. Ruby's mother has passed away and she is going to live with her father. Ruby is angry at her mother for dying, at her father for abandoning her and at her aunt for sending her away. The story is conveyed through Ruby's poems and emails.