Bucky Barnes was a close friend to Steve Rogers. He was recruited to become a member of the Howling Commandos before plummeting off a train and presumed dead. Though he survived and began a HYDRA soldier under the alias, Winter Soldier. After Steve Rogers confronts him, he becomes a close ally during the response to the Sokovia Accords.
Bucky Barnes was the child sidekick to Steve Rogers. He joined Captain America in multiple missions, before being presumed dead after he tried to defuse a bomb. Later, it became apparent that Bucky was resurrected as a soviet assassin, under the code name the Winter Soldier. He later regains his memories before briefly taking the mantle of Captain America.