Alister: The Archives of Edgar Brave, Book 1

But the world on the other side had its own troubles. The Coastal Cliffs had been on the edge of war since the raids began. Now Edgar Brave, taken in by a warrior tribe on the eve of battle, must find his brother and live long enough to figure out how to return to his home on the other end of the universe. If he fails, he could lose the one person in his life that ever truly mattered.