Peril's Gate (Wars of Light and Shadow, Book 6)

Barely escaping with his life from the evil machinations of his half-brother Lysaer, Prince of Light, who is determined to kill him, Arithon flees into the winter wilds where he must learn to survive the violent storms, but Arithon soon discovers he is not alone and is forced to choose between dying at his enemies' hands or uniting with a dangerous enchanter who had once destroyed his royal ancestors.