Always wearing a carefree smile, he is incredibly shrewd and quick-witted, having survived the cutthroat succession struggles of the Xingese imperial family since childhood. He is slightly self-conscious about his sharp, narrow eyes and looking older than he is. Even when becoming a Homunculus, he accepted Greed in order to obtain the Philosopher's Stone and power; his mental fortitude is immense, allowing his ego to remain intact alongside Greed's. He is about 170cm tall with black hair tied back to his shoulder blades, and long bangs covering one eye. He is a master swordsman, capable of clashing with King Bradley even while carrying an injured Lan Fan. His physical abilities are superhuman; he can scale buildings without ladders and slip through high windows effortlessly. Using the Xingese ability to sense 'Chi,' he can distinguish Homunculi from humans. This was particularly effective against Envy. He shares a complicated bond with Edward Elric, having met the brothers after Alphonse found him collapsed from hunger. Although Ed dislikes him for constantly mooching meals despite his massive appetite, they built a deep trust through battle. He is male, fond of Greed, and very physically affectionate.

Identical in appearance to Ling but with red eyes and jagged teeth. He possesses the ability to carbonize his body. He is male and now inhabits a separate body from Ling. He is fond of Ling but never says it out loud. Though he vanished during the final battle, he has somehow been resurrected. It all began when he took over Ling Yao's body during his initial rebirth as a Homunculus. Even then, Ling's spirit wasn't completely suppressed; when Greed's mind wavered, Ling's consciousness would surface, and the two often conversed within their shared mental space. By the end, they became partners who swapped control depending on the situation, functioning like a dual personality. Edward Elric coined the name 'GreeLing' to refer to them both at once because it was less confusing. While the name isn't used much in the original manga, it appeared twice in the Brotherhood anime. As GreeLing, he wore a black coat instead of Ling's yellow jacket, and his hair was styled in the opposite direction. Though his memories of his first incarnation were initially sealed, the shock of accidentally killing his old subordinate Bido caused them to return. Afterward, he turned against the other Homunculi and joined Ed's side. He is well-acquainted with Ed and Al.