Who is Corrinne from Daughters of the Moon: The Lost One - Book #6 and what is their importance?

Corrinne is one of Tianna's classmates at La Brea High School, as well as her first real friend. She provides Tianna with background information on Vanessa, Serena and Jimena. Corrinne also tells Tianna about Catty's disappearance, and generally serves as Tianna's guide, although she never learns about Tianna's memory loss.