Magician's Gambit (The Belgariad, Book 3)

Ce'Nedra, Imperial Princess of Tolnedra, had joined a dangerous mission to recover the stolen Orb that supposedly protected the West from the evil God Torak. And somehow, she found herself feeling quite tender for Garion, the innocent farm boy, who would be forced into the strange tower in the center of all evil to retrieve the Orb by himself.