Ling Yao is the twelfth crown prince of the eastern nation of Xing and the liege of the Yao clan. He travels to Amestris in search of the Philosopher’s Stone, which he believes holds the secret to immortality. His motivation is rooted in the declining health of his father, the Emperor of Xing, and the intense competition among the Emperor’s many children for the throne. Ling hopes that obtaining the Philosopher’s Stone will help him rise in the order of succession and secure the welfare of his clan.

In personality, Ling is a study in contrasts. He is often laid-back, with a perpetually hungry demeanor, and he displays a crafty, opportunistic side—frequently exploiting others, particularly Edward Elric, for meals or favors. He has a light-hearted, humorous nature that leads to playful rivalries, but beneath this easygoing exterior is a deeply noble and serious ambition. He is fiercely loyal to his people and his bodyguards, Lan Fan and Fu, and believes that a ruler’s primary responsibility is to protect and serve their subjects.

Ling’s role in the story begins as a newcomer from a foreign land who seeks the same object as the Elric brothers. He initially uses deception and combat to gather information, but he eventually becomes a key ally in the fight against the Homunculi. A pivotal turning point occurs when Father, the leader of the Homunculi, decides to make Ling the new vessel for the Homunculus Greed. Ling accepts this transformation, having Greed’s Philosopher’s Stone implanted in his body. Rather than being consumed, Ling retains his own consciousness and develops a symbiotic partnership with Greed. The two beings share control of his body, allowing Ling to call upon Greed’s powers while still acting according to his own will. This dual existence creates internal conflict but also grants him immense abilities.

Key relationships shape Ling’s journey. His bond with his bodyguard Lan Fan is one of deep mutual trust and devotion; she risks her life for him repeatedly, and he is willing to do the same for her. His relationship with Edward Elric is marked by a mix of rivalry, camaraderie, and humor—Ling frequently uses Edward’s money to annoy him, yet they fight side by side against common enemies. Ling also clashes with Wrath, the Führer King Bradley, over their differing philosophies of leadership. Despite these conflicts, Ling earns the respect of his adversaries through his cunning and bravery.

Over the course of the narrative, Ling undergoes significant development. He begins as a prince driven largely by personal ambition to gain power and immortality. Through his experiences in Amestris—especially his partnership with Greed, the loss of Fu, and his interactions with the Elrics and other characters—he grows to understand that true leadership is about serving others rather than seeking personal gain. By the end of the story, after Father’s defeat, Ling returns to Xing with Lan Fan and becomes the new Emperor, having secured the throne and his clan’s future.

Notable abilities include Ling’s exceptional martial arts skill, honed through Xingese training, which makes him a formidable hand-to-hand combatant even without alchemy. After becoming Greed, he gains enhanced durability and the power to manipulate the substance of his body, forming an impenetrable shield known as the Ultimate Shield. He can also switch between his own consciousness and Greed’s, allowing him to make tactical use of Greed’s abilities while preserving his own identity. This combination of physical prowess, strategic thinking, and the supernatural powers of a homunculus makes him a versatile and dangerous opponent.