James Buchanan Barnes (Earth-199999)

Civil War

Barnes was believed to be the perpetrator of a bombing in Vienna that killed several people, including 's King . Captain America tracked him to his hideout in and attempted to reason with him. However, despite recognizing his friend, Barnes fled when the building was breached by the and was immediately attacked by . After a short struggle, Barnes escaped and fled through the streets of Bucharest, with Rogers and the other man hot on his heels. Eventually they caught up with him but were immediately surrounded by German Special Forces, backed up by the sudden arrival of . Barnes, Rogers, T'Challa, and Wilson (who had been backing up Rogers) surrendered.

Bucky was detained for psychiatric evaluation and extradition. His evaluation was interrupted by a sudden and complete loss of power to the building. The used key phrases to reactivate Barnes' Hydra programming, putting him into a violent state. He broke out of the cell and attacked Rogers and Wilson upon their arrival, knocking Falcon out and throwing Rogers down an elevator shaft. He then moved through the facility intent on escaping at any cost, and injured or escaped Black Widow, Black Panther, , and . Reaching the helipad, Bucky boarded a helicopter, but before he could take off, Rogers grabbed onto it preventing him from flying. Bucky crashed the chopper instead, and grabbed Rogers by the throat from inside the cockpit as the wreckage of the helicopter fell into the water below. Barnes was knocked unconscious when his head hit the windshield.

Bucky later came to in a garage, his metal arm locked in a vice. When Rogers confronted him, Barnes revealed that he remembers him and the events that had just transpired: someone had reactivated his programming in order to uncover the location of the five other Winter Soldiers. Barnes then joined forces with Rogers and Wilson to track down their mysterious foe. Captain America also brought in , and to help them.

Arriving at the airport in , Rogers and his allies were confronted by Iron Man and his allies, including War Machine, Black Panther, Black Widow, , and . Stark tried to reason with Rogers, but a fight quickly broke out between the two teams. After a while, it became clear that Rogers' allies were losing. When Lang grew in size to create a distraction, Barnes and Rogers broke away from the fight to flee to a quinjet and escaped, although the rest of the group was not so lucky.

Steve and Bucky flew to to confront Zemo. They were surprised by Stark's sudden arrival. Stark had come to realize what a threat Zemo was and called a truce with Rogers in order to better find and capture him.

The trio then proceed to the chamber, where the Winter Soldiers are held in cryogenic stasis. Zemo gained their attention via the intercom, revealing that it was all a ruse; the Winter Soldiers were dead, each with a gunshot wound to the head. Zemo revealed himself, and explained his reasoning: he blamed the Avengers for the death of his family in the the previous year. Zemo played video footage of the deaths of Howard and Maria Stark, revealing that it was the Winter Soldier who was responsible. When Rogers revealed that he had known this all along, a distraught and enraged Stark turned on them both, resulting in a brutal, protracted brawl between them. Stark blasted Barnes' metal arm off, knocking him down due to the trauma. While Iron Man subsequently overpowered Rogers in combat, Bucky managed to knock him off balance while on the floor, giving Rogers the opportunity to turn the tide of the fight and destroy the power source of Stark's armor. Rogers wrenched his shield free from Stark's chest plate and helped Barnes to his feet, discarding the shield to concede Stark's accusation that he didn't deserve it.

T'Challa had remained hidden throughout the confrontation, and had apprehended Zemo as the battle inside the Siberia installation wound down. He apologized to Bucky when they crossed paths outside the facility, and offered his assistance in undoing Hydra's mental programming. Bucky was put into cryogenic stasis at his own request while T'Challa's sister worked on a cure. Bucky was eventually cured, and continued resting in Wakanda once he woke up.