Winter Soldier

James "Bucky" Barnes was a soldier and the childhood friend of Steve Rogers. He was a member of the Howling Commandoes.

Captain America: The First Avenger
After meeting him in his childhood, Bucky became Rogers best friend. After the Pearl Harbor attack, Bucky enlisted in the US army and assumed the title of Sgt. Barnes. Then he and his unit were taken prisoners in Italy by HYDRA, but Captain America freed them and formed an elite team. During the war, Bucky served in the Howling Commandos and fought against the Nazis and HYDRA. Bucky, Captain America and Gabe Jones zipline on to the top of a HYDRA train. Bucky takes Captain America's shield and blocks him while he's down, but clearly not having the upper body strength to hold on to it when getting hit it shoots him out the side of the train and Cap is unable to save him, letting him fall into a icey river below.

The Avengers
Bucky Barnes' files is among the ones studied by Steve Rogers, awakened at the present days. Oddly enough, he's reported as "Missing in action", implying that S.H.I.E.L.D. thinks he may be still alive.

Relationships

 * Captain America - Teammate, Friend and Leader
 * Chester Phillips - Leader
 * Red Skull - Enemy
 * Arnim Zola - Enemy