Falcon And Winter Soldier Explained - Who Is The New Captain America?

The Government-Approved Captain America - U.S. Agent In The Comics

John Walker was initially introduced as the Super-Patriot in 1986's Captain America #323 by Mark Gruenwald and Paul Neary. He grew up idolising the military after his brother died in Vietnam but was never able to attain the war hero status he desperately coveted, and so looked elsewhere after his honourable discharge from the army.

Walker eventually gets super soldier powers from a shadowy figure known as the Power Broker, and becomes a corporate sponsored superhero known as the Super-Patriot. He decides to start publicly dissing Captain America as not being patriotic enough, and when Cap decides to no longer take on the mantle after the the Commission on Superhuman Activities implements a rule that would force him to abide by the government's whims, Walker steps in as the new Cap.

Essentially, John Walker was intended as a critique of unchecked jingoism and nationalism. He's all too willing to be a government stooge because he doesn't understand that the value of Cap as a symbol transcends any government institution. He eventually finds this out the hard way after partaking in some classic Containment-inspired war crimes in South America, later abandoning the Captain America mantle and becoming an anti-hero of sorts under the new identity of U.S. Agent.

But it wasn't a quick transition. Walker continued to work for the government and was prone to violent outbursts, clashing with his teammates on the West Coast Avengers until a pivotal encounter on the Mexico border left his faith in the institutions he was serving shaken.

From there, Walker became a more traditional superhero - working independently of the government and renewing his membership of the Avengers West Coast - although one that still had plenty of issues. He never was quite able to live up to the legacy of Steve Rogers, but as his own hero, he eventually started to make the right decisions after a long and protracted period of trial and error.