In the sequel film Mobile Suit Gundam Wing: Endless Waltz, Chang Wufei is a 16-year-old Gundam pilot of Chinese descent, originating from the L5 Colony Cluster. His past is defined by profound loss, which shapes his identity as a warrior. At the age of fourteen, he was forced into an arranged marriage with a fellow clan heir named Meilan, who would later die in battle piloting a prototype mobile suit to protect their colony. Despite their initial ideological clashes, her sacrifice became the catalyst for his life's mission. Adopting her fierce spirit and her chosen name, he began calling his Gundam Nataku, believing her soul resides within the machine, and dedicated himself to the pursuit of justice she embodied.

Wufei's personality is marked by an intense, often contradictory, internal struggle. He is a staunch adherent to a strict code of honor, believing that the strong should not prey on the weak and that justice must be proven through victory. This drive for victory leads him to favor fighting alone, frequently criticizing others he deems weak or uncertain. Despite this hot-blooded exterior, he possesses a sharp, analytical mind and a cool head in combat, having once been a scholar who was cynical about war and justice before his wife's death reshaped his worldview. His pride is a significant vulnerability; he is deeply affected by personal defeat, such as his humiliating loss to the OZ leader Treize Khushrenada in a swordsmanship duel, which temporarily shattered his confidence.

By the time of Endless Waltz, set one year after the original series' conclusion, Wufei has lost his way. Having dedicated his entire life to fighting, he finds himself obsolete in a world that has embraced total pacifism. Burdened by a lingering sense of defeat from his final, unsatisfying victory over Treize, he grows to resent the peacetime citizens who, in his view, have carelessly discarded the sacrifices of soldiers. To resolve this crisis of purpose and test the validity of the new peaceful era, he makes the dramatic decision to become an antagonist. He joins the Mariemaia Army, a rogue faction aiming to seize the Earth Sphere, piloting the powerful Altron Gundam against his former allies.

His role in the film serves as the primary ideological opposition to the other Gundam pilots, particularly Heero Yuy. Wufei confronts Heero twice, arguing that those who were created as tools for war cannot simply abandon their nature and that a world without conflict is an illusion that dishonors the memory of fallen warriors. However, through these clashes, especially when Heero refuses to fight back with lethal intent, Wufei is forced to confront the consequences of his own actions. He realizes that continuing down his path would only repeat the tragedies that led to the destruction of his home colony and the loss of his wife's grave. His turning point comes when he witnesses ordinary citizens in Brussels rising up to protest the coup without his intervention, demonstrating a different kind of strength.

Wufei is an exceptionally skilled combatant, proficient in martial arts and swordsmanship, and is considered one of the strongest pilots among the five, capable of piloting the mentally overwhelming Zero System with more stability than most. His growth in Endless Waltz is the resolution of his long-standing internal conflict. By the end, he accepts that fighting for its own sake is not the only path. In a final symbolic act, he pilots his beloved Altron Gundam (Nataku) back to his ancestral home and self-destructs it, finally giving his wife's spirit a peaceful rest and moving on from his grief. He ultimately accepts an invitation from his ally, Sally Po, to join the new peacekeeping organization, the Preventers, finding a new way to apply his strength and honor in a world striving for peace.