Peng is a young snow leopard who is a former potter before he took to traveling and is a self-taught prodigy in martial arts.
He visited the Valley of Peace during its Peace Jubilee and was forced into a confrontation with Temutai's nephew, Jing Mei. When the leopard quickly defeated the young water buffalo, the deeply impressed Po persuaded Master Shifu to consider taking him in as a student. Unfortunately, the combination of the cub's likably humble character and his considerable skill drew him so much favor with Jade Palace's residents that Po grew threatened and little jealous, especially when the cub mused of becoming the Dragon Warrior himself.
In response, Po falsely claimed to Peng that Shifu rejected him. Unfortunately, Peng in a rage decided to prove himself by killing Temutai and immediately attacked the water buffalo in his tent. Po, alarmed at his mistake and the cub's murderous overreaction, attempted to intervene, but the fight drifted into the festivities and provoked a riot. Eventually, Po is finally able to confess his deception and apologize to Peng, who immediately calmed down and similarly apologized for losing his temper, allowing the unwitting rivals to reconcile in the spirit of the occasion.
After the Jubilee, Peng decides to leave to continue his quest: to find his uncle Tai Lung. At that, Po harbors some concern of how this boy, who is apparently unaware of his relative's crimes, will react when he learns that the Dragon Warrior (Po) struck him down in battle.
Role in Ultima
While he was wandering the interdimensional wastelands created by the destruction of his and several other worlds, Peng received an unexpected visit from Padro Lodo. Lodo told Peng that Po had brutally killed Tai Lung. Peng was enraged, and Lodo had offer Peng the chance for revenge. Peng accepted it. Now Peng is a powerful member of the Harbingers.
Peng has not met his revived Uncle yet. Lodo does not want this to happen, fearing that Peng may learn the truth.
Another point of interest, Lodo was holding a strange shard next to Peng, during their talk.