James Buchanan "Bucky" Barnes

Bucky Barnes is the young mascot of the army unit where Steve Rogers serves under Sergeant Duffy, a boy attached to the soldiers stationed at the camp. His life changes the night he wanders in on Steve midway through a costume change and discovers that the bumbling private is secretly Captain America.

Rather than keep the secret at arm's length, Bucky presses Steve to let him join the fight, and wins a place at the hero's side as his sidekick. Taking up the role, he stands with Captain America against the Nazi saboteurs threatening the war effort, the two of them working as a pair from that point on.

Bucky is Captain America's closest companion and remains determined to recover him after the Red Skull captures and brainwashes him. During the assassination plot, Bucky is, himself, captured by the Nazis and subjected to an execution threat, but he eventually leads a rebellion among the prisoners and escapes.

Bucky then searches for Captain America and discovers that his friend is being used as a weapon against the Allies. He manages to infiltrate the Nazi operation and reaches Rogers before the assassination can be completed. His intervention helps give Captain America the opportunity to resist the brainwashing and prevents the Red Skull's plan from succeeding.