Avengers: Endgame - Every Mystery The Russos Have Answered (So Far)

13. Captain America's Alternate Reality

The Question

There's been lots of speculation on Captain America being able to jump back in time and live the life that was stolen from him again. So what gives? Were there two Caps co-existing? Did Cap affect the timeline since he seemingly remained in the main timeline to pass on his legacy? Was this a closed time loop?

The Answer

In short, Cap didn't change anything in the main timeline. He created his own alternate future where he was still a good man, but where he seemingly wasn't Captain America, at least not in terms of wearing the costume:

"He lived a completely different life in that world. We don't know how exactly his life turned out, but I'd like to believe he still helped many others when they were needed in that world. Yes, there were two Captain Americas in that reality, it's just like what Hulk said, what happened in the past has already happened. If you go back to the past, you simply created a new reality. The characters in this movie created a new timeline when they went back to the past, but it had no effect on the prime universe. What happened in the past 22 movies was still canon."

And in terms of the closed time loop part, the Russos say it's more like the branch theory that Hulk and the Ancient One both talk about in Endgame. You can't change the future by going back to the past - instead, you create another alternate timeline:

"It’s not butterfly effect. Every decision you made in the past could potentially create a new timeline. For example, the old Cap at the end movie, he lived his married life in a different universe from the main one. He had to make another jump back to the main universe at the end to give the shield to Sam."

Quite HOW he managed that without any Infinity Stones is not clear.