Pendragon Before the War - by D.J. MacHale (2nd Book)

Paperback. "Pendragon: Before the War: Book Two of the Travelers is a prequel to the main Pendragon series that follows the separate storylines of three characters before they became Travelers for Halla. The book features: Elli Winter discovering Mr. Pop, Alder learning to become a Bedoowan knight on Denduron, and Aja Killian participating in a dangerous competition on Veelox."