The Fullmetal Alchemist Chronicle Guidebook states Ling becomes emperor of Xing the same year he returns to his country at the end of the series. Ling first came into the series as a Prince of Xing looking for immortality to be able to save his people and become the next emperor of Xing. He came into Amestris with Lan Fan and Fu. During his search he runs into Edward and Alphonse Elric. After being eaten by a homunculus, Gluttony, he, Edward, and another homunculus, Envy, try to find a way out of the stomache of the monster. Once they escape they encounter 'Father'. Ling, in order to gain immortality, allows Father to make him a homunculus. He allows Greed to take over his body.