“Steve Rogers and Bucky are both orphans and kind of like brothers,” Stan said, professing that he was unfamiliar with the comics before getting cast, “They kind of grow up together and look after each other. It’s a very human, relatable thing. And growing up in the Army is a very specific thing. There’s a certain way these guys carry themselves, there’s a certain etiquette, a certain body posture, the way that they interact. So I went back and read the comics and watched a lot of documentaries on World War II. “Band of Brothers” was very helpful.”
Though the film looks to set up Barnes as a teammate soldier of Rogers, the character was, in the comic book continuity, a teenage orphan too young to join the army and who instead was brought to the battlefield as a mascot. After learning the identiy of Captain America, Barnes became his sidekick until he was presumed killed in action (alongside Cap). It was revealed decades later that Barnes had been captured by Soviet forces and reprogrammed into an assassin known as the Winter Soldier. Following Marvel’s Civil War, Rogers was again believed dead and Barnes inherited the mantle of Captain America himself.