Faerie Wars (2003)

Henry Atherton thinks his life is spinning out of control. But nothing prepares him for the invisible portal in old man Fogarty's backyard . . . and the unexpected stranger who comes through it.
            Pyrgus Malvae, crown prince of the Faerie realm, is on the run. Too many people want the rebellious young heir dead:  a scheming sorcerer, a powerful demon, the malignant leader of the Faeries of the Night, and maybe even a hidden traitor within his father's court.
            Henry and Pyrgus come from very different worlds, but it may be up to Henry to save all of Faerie from being conquered by the Nightside, even if it means crossing over to a magical realm where nothing is ever what it seems . . . and no one can be trusted.