Who is Big Roscia from Roman Blood and what is their importance?

Big Roscia is Sextus Roscius' eldest daughter. Her first name is never mentioned, hence, the word "Big", is used to distinguish her from her younger sister. Big Roscia is described as a beautiful girl, who is a victim of incest at the hands of her father. As a result, she will do anything in her power to see her father destroyed. Big Roscia is a sexual, young woman, who has no qualms about using her body to get what she wants.