Avengers: Endgame used time-travel, with its own complicated rules that only made Captain America’s decision more confusing than emotional.
After years as one of the biggest heroes in the world, and 70 years frozen underwater, Captain America was ready to retire, and when he saw the chance to go back in time and live a more relaxed life, he took it, and so he spent the rest of his life next to Peggy Carter. Cap’s decision has made fans wonder why he didn’t change some of the most horrifying events in history, among other questions that haven’t really been answered as everyone seems to have a different opinion. Another question (though less intense than the previous ones) is who knew about his time-traveling, and the answer can be tricky.
As seen in Peggy Carter knew about his time-travel secret, and given that Steve was the father of her kids, they probably knew about it, too. Again, Captain America was a big hero, and they would have noticed their father was identical.
As previously mentioned, Captain America didn’t do anything to change history, opting for a more low-key life, so it’s unlikely that other characters knew about it. Nick Fury might have been aware, but only by chance. Peggy Carter was one of the founders of S.H.I.E.L.D, so it’s not totally crazy that Fury and time-travel Steve could have crossed paths at some point, with the latter explaining why there were two of him. Of course, characters like Falcon, Bucky, Hulk, and the rest of the heroes from his original timeline knew about it, but only decades later.
The time-traveling rules and consequences in Avengers: Endgame will continue to be a topic of discussion among fans until the writers and directors finally agree on their explanations, which won’t happen anytime soon (or perhaps ever). At the moment, there is no official, canon explanation for how the time-travel works, just off-the-cuff reasoning to answer difficult questions. But, for now, fans can carry on with their lives knowing that at least Peggy and their kids knew Captain America’s time-travel secret.
