Phantom Hearts

Two college roommates, Orion and Caelum, embark on an unexpected journey when they discover they are destined to become an interdimensional hero known as Stardust. Orion, a half-ghost and the ghost king to be, is haunted by a lonely, troubled past. Caelum, on the other hand, comes from a loving family and is just your average person, or so he thought. As they navigate their newfound abilities and the challenges that come with their role as heroes, they must learn to trust each other and rely on their unique strengths to save their world from an impending cosmic threat.
This is going to be a beta version of a novel (maybe series) I'm writing so please give me suggestions and ideas in the comments. Tags will be added as I think of them.