Birthright by B.J. Keeton

Damien Vennar used to be a god.

As a Charon, Damien had the power to create universes. Then, five hundred years ago, he gave it all up. He suspended the nanotechnology that granted his magic, and he began to age—and eventually die—like anyone else. For centuries, Damien has lived among those who once worshiped him, his past fading into myth and legend.

Hundreds of years later, when 14-year-old Ceril Bain finds Damien’s old Flameblade buried in his grandfather’s garden, he is put on the fast-track to follow in Vennar’s footsteps. Over the next six years, Ceril trains to become a Charon aboard a dimensional-traveling ship left behind from the Charons’ once widespread empire. Just as Ceril is preparing to undergo his Rites and finish his training, the ship loses power. Stranded, Ceril and four of his classmates are given their final assignment: find Vennar so he can fix the ship.