Avengers: Doomsday directors the Russo Brothers wouldn’t have returned to Marvel with Robert Downey Jr. if they couldn’t make a sequel “on equal footing with Infinity War and Endgame”

Avengers: Endgame quickly became the highest-grossing film of all time when it stormed cinemas in 2019. James Cameron’s Avatar has since reclaimed pole position (thanks to a subsequent re-release in China), but half a decade on, the fourth Avengers movie is still the most successful superhero film ever made.

As the final culmination of Marvel’s first three phases, Avengers: Endgame was a natural jumping off point for many, including Iron Man star Robert Downey Jr., along with co-directors Joe and Anthony Russo. It’s in the name, after all, yet it turns out Endgame wasn’t quite as final for everyone involved as fans once believed.

This summer at San Diego Comic-Con, Marvel announced that the Russo Brothers are returning to helm Avengers: Doomsday as well as Avengers: Secret Wars after Destin Daniel Cretton stepped down to focus on the Shang-Chi sequel (he’s since been reported to be the Spider-Man 4 director, too). And that’s not all. The panel ended by revealing that Robert Downey Jr. is making a surprise return to the MCU as the movie’s villain, Doctor Doom, primarily known as the chief antagonist of the Fantastic Four.

Pitting the Avengers against a foe who looks identical to founding member Tony Stark is diabolical in more ways than one, but where did this plan come from in the first place? Whose idea was it to bring Robert Downey Jr. back to the MCU in this new pivotal role? 

During an interview with GamesRadar+ at MCM Comic Con 2024, Avengers: Doomsday co-director Joe Russo explained how this twist came about organically through the bond he and Anthony share with Downey Jr. 

“We’re all very close,” says Joe. “We had been working on another project before Marvel approached all of us – so we’re working on another project with Robert – and there was a story that evolved through conversations that we got very excited about. Because it’s always got to be the story.”

The specifics of this story aren’t clear just yet, although it’s almost certain that the multiverse will play a key role in Downey Jr.’s return. Whatever happens though, Joe promises that we can expect something “really explosive” when Avengers: Doomsday arrives in theaters.   

“Why would we come back if we didn’t feel like we had a story that had that possibility of being on an equal footing with Infinity War and Endgame unless there’s a kernel there for an idea that’s really explosive?”

Infinity War and Endgame will be hard to match, but if anyone can do it, it’s the Russo Brothers, who previously wrangled over 20 Marvel movies into a fitting conclusion that broke hearts and box office records alike. 

With filming for the fifth Avengers movie starting in spring 2025, we’re still a long way off from getting to see how this will play out. But in the meantime, the Russo Brothers are preparing for the upcoming release of their next movie, The Electric State, which is due to hit Netflix on March 14, 2025.

Along with Stranger Things star Millie Bobby Brown, the Russo Brothers are set to reunite with MCU stars Chris Pratt and Anthony Mackie as well as long-time Marvel collaborators Christopher Markus and Stephen McFeely, who developed The Electric State script based on a graphic novel by Swedish artist Simon Stålenhag.

While you wait, check out our guide to the best Netflix movies to stream now to fill out your watchlist, or see all the upcoming Marvel movies and TV shows.