Who is Mia Rinalti from Frostbite and what is their importance?

Mia Rinalti is a student at St. Vladimir's Academy. Mia is Lissa's sworn enemy, making her Rose's enemy as well. However, when there is a second attack by the Strigoi and Mia's mother is killed, Rose and Lissa reach out to her. Mia goes with Mason to Spokane to kill the Strigoi reported to be there. When Rose goes to rescue Mia, Mason, and Eddie, they are all kidnapped. In the end, Mia uses her magic element, water, to help Rose fight the Strigoi.