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

Derek is one of Tianna's classmates at La Brea High School. He is described as having long red hair, and he has a crush on Tianna. Tianna, however, doesn't remember him because her memories have been stolen. Derek later puts Tianna in danger when he believes Mason and Justin's story and leads them to her at Planet Bang.