Ling Yao

Ling Yao is a Xingese character exclusive to the Manga. He first appears in Chapter 32, in Rush Valley. He is a prince of the eastern nation of Xing. He is the essence of "Noblesse Oblige" - "privilege entails to responsibility". Though haughty, arrogant and ambitious, he cares deeply for his servants and people - a feeling that is returned, especially from his bodyguard, Ran Fan. Those outside his responsibilities are often less fortunate - as Ed learns from his habit of running up room service bills. His goal in life is to become immortal and become the emperor of his country of origin. He enjoys flirting with Winry and becomes a close friend of Ed's.

He instantly becomes a dedicated opponent of Führer King Bradley due to the Homunculus' belief that those in one's service who can no longer perform should be discarded. Ling is a devoted believer in fealty, that is, a King cannot exist without a people to support him. Bradley simply responds that a King is merely one who is powerful enough to compel obedience in others.

Ling leaves his country and heads to Amestris to find a way to become immortal, so he can gain the throne. In Xing, many families are striving for the position as emperor. The current emperor is ill, so if Ling can find a method of immortality and gives it to the emperor, he will be chosen as an heir (the emperor will retire eventually). Ling begins to look for the best lead he has: The Philosopher's Stone.

In The Belly of The Beast
During the fight with Gluttony and Envy outside of Dr. Knox's house, Gluttony eats Ling, Envy, and Ed, transporting them to the dark world that is Gluttony's belly. Ling and Ed try to make their way out, looking for any end to the abyss. They become extremely tired and hungry. Eventually, Envy catches up to them, and tells them that they are and are not in Gluttony's belly. They are in a fake Door of Truth. Envy reveals his true, monstrous form, and attacks them. Ed uses Envy as payment to open the Door of Truth and transport them to Father's hideout.

Immortality Obtained
After escaping Gluttony's belly, Ling, Ed, and Envy appear in Father's hideout. While Envy holds Ling and Ed down, Father approaches Ling and touches his own forehead, opening an eye on his head. A red blob, the Philosopher's Stone, seeps out of the eye on Father's head, and he drops it into one of Ling's wounds, telling him that Greed's position is currently empty. Inside Ling, his spirit and the invading spirit from the Stone are fighting. The spirit, who reveals himself as Greed, tells Ling that he wants his body and that he can offer him great power. Ling tells the spirit that he will do whatever it takes to gain power, and gives the spirit his body. Greed takes control of Ling's body.