Complex sentence: Over time, Zuko's loyalties and moralities shift as he grows to sympathize with the people that the Fire Nation has terrorized, ultimately joining the Avatar to help end the Fire Nation's tyranny and restore balance to the world.
Split into simpler sentences: Over time, Zuko's loyalties and moralities shift as he grows to sympathize with the people that the Fire Nation has terrorized. Ultimately he joins the Avatar to help end the Fire Nation's tyranny and restore balance to the world.