Avengers: Endgame is a magnificent feat in and of itself. The movie not only had to pay off Avengers: Infinity War, but 11 years worth of stories that came before it. The people responsible for doing that are Stephen McFeely and Christopher Markus. They have written all three Captain America movies, and also wrote Infinity War.
Talking to Variety, the duo talked about how big of an undertaking it was to write Endgame.
McFeely: “We were nervous at that moment because it was such a big project. It would take up so much of our lives and it would be the biggest puzzle that we ever would put together as writers. That was scary and we we said okay, we should probably do scary things and if successful, it might be really amazing.“
Markus: “We knew this would never come around again. For someone to offer you the culmination of this big of an undertaking, that’s never going to happen again. And as consuming and sometimes painful as it was over the past four and a half years that we’ve been working on it, it will never happen again. To walk away from it would seem like something that you’re really going to kick yourself about later.“
The genius of Avengers: Infinity War was making Thanos the main character. It is his story. The superheroes you know and love are just supporting characters reacting to the events Thanos is causing. Because of that, the movie is more accessible than ever before. Endgame doesn’t have that luxury, it is not really one person’s movie. So even though both of them were developed together, Endgame seemed like the trickier one to get right just because of the sheer size of it.
For all intents and purposes, they nailed it. Of course, I have been invested in this universe since the very beginning, so the payoff was sublime. But I have heard even the most casual of fans, who have been dragged to these movies by friends found it enjoyable too.
It is remarkable that Marvel pulled this off, and Endgame was a pretty satisfying conclusion to 22 movies. Markus and McFeely are a big piece of that success.