Fu is a supporting character who serves as one of the two personal bodyguards to Prince Ling Yao of the Xing Empire. He is an elderly man, identifiable by his small stature, heavily wrinkled face, spiky gray hair, and a bushy mustache. His standard attire is a practical black outfit suited for combat and stealth, which includes fingerless gloves, boots with light armor plating, torso armor, and a white bandana worn around his forehead. He typically wears a mask that covers the lower part of his face down to his nose, which is marked with the Yang half of the Yin-Yang symbol.

As a retainer of the Yao Clan, Fu is defined by a profound and unwavering sense of duty. His personality is serious and stern, reflecting the discipline gained from a lifetime of service. He is a traditionalist warrior who holds the values of sacrifice and loyalty as the highest honors, believing that giving one's life for one's lord is the ultimate expression of fealty. This philosophy guides all his actions. Despite his stern exterior, Fu possesses a deep and caring heart, particularly for his family. This is most evident in his relationship with his granddaughter, Lan Fan, who serves as Ling's other bodyguard. While he holds her to the same exacting standards as himself and can appear harsh when she fails in her duties, he is fiercely protective of her and is driven to a state of righteous fury upon seeing her injured.

Fu's primary motivation is the success of Prince Ling's quest to secure the secret of immortality, which would allow the prince to gain favor with the aging Emperor of Xing and become a candidate for the throne. For Fu, this mission is not just about serving his prince; it is about securing the future of his clan and the legacy of his family. He feels the pressure of the Emperor's deteriorating health and pushes himself and his prince to achieve their goal within a limited time. Initially, he is skeptical of the Amestrian people and their alchemy, scoffing at the idea that his prince should seek help from commoners like the Elric brothers. However, his loyalty never wavers, and he is willing to lay down his life if it means Ling can obtain the power needed to claim the throne.

Within the story, Fu acts as the strategic and experienced anchor for Ling's party. While Ling is ambitious and sometimes impulsive, and Lan Fan is devoted but young, Fu provides wisdom and a tactical mind that has been honed over decades. He is often sent ahead to gather intelligence or to accomplish tasks that require discretion and a level head, such as escorting the fugitive Maria Ross safely to Xing. His skills are invaluable during the conflict against the Homunculi, as he possesses the ability to sense the chi, or life energy, of others. This sensory ability allows him to detect the presence of Homunculi, who possess the distorted chi of many souls within them, and even to locate allies in total darkness. His most critical contribution takes place during the final battle in Central City, where he confronts King Bradley, also known as the Homunculus Wrath.

Fu's most significant relationships are with Prince Ling and his granddaughter Lan Fan. His relationship with Ling is one of absolute fealty, but it is not without mutual respect. Fu has dedicated his life to the Yao clan and sees Ling as both his lord and the future of their people. In turn, Ling values Fu not just as a retainer but as a trusted mentor and companion. His relationship with Lan Fan is more complex, blending the roles of a stern master and a loving grandfather. He trains her to be a warrior, and in their mission, he treats her as a fellow soldier, which is why he reacts with anger when she wallows in self-pity after losing her arm. Yet this anger crumbles instantly into sorrow and despair, revealing his profound love for her. His hatred for Bradley is personal because the Führer was the one who severed Lan Fan's arm, making his final confrontation with Wrath as much an act of familial vengeance as it is a part of his duty.

Regarding development, Fu is a character who demonstrates little change in his core beliefs, as he begins and ends the series as a model of the self-sacrificing warrior. The story instead puts his unwavering philosophy to its ultimate test. When he is mortally wounded by Bradley, he attempts a final, desperate act of sacrifice, strapping grenades to his body and trying to take the Homunculus with him. Though the attack fails, his action creates the critical distraction that allows another soldier to wound Bradley. In his final moments, he apologizes to Ling not for his death, but for his failure to be of more use, a testament to his selfless mindset. He dies fulfilled, having given everything he had for his prince.

Fu is an exceptionally skilled combatant whose abilities defy his advanced age. He is a master of Xingese martial arts, which involves high-level acrobatics that allow him to dodge attacks and move with incredible speed, as seen when he effortlessly overwhelms the armored Alphonse Elric. He is also a weapons specialist, proficient with swords, kunai knives, and other bladed weapons, skilled enough to briefly hold his own against the superhuman King Bradley. His most distinctive techniques, however, involve the use of various explosives. He carries an arsenal of bombs and grenades of Xingese make, including flashbang grenades to disorient enemies, smoke grenades for cover, and more powerful explosive devices for direct damage. His ability to sense chi gives him a massive tactical advantage, effectively allowing him to see in the dark, read the flow of energy around him, and detect the presence of souls from a great distance. Despite his small stature and elderly appearance, Fu is a formidable warrior whose combination of wisdom, speed, and lethal skill makes him a valuable asset and a respected figure in the struggle against the Homunculi.