How Robert Downey Jr. Is Preparing for His Marvel Comeback as Doctor Doom: ‘It’s a Very Intense Process’

Robert Downey Jr. is beyond ready to be Doctor Doom.

Co-directors Joe and Anthony Russo shared how seriously the former Iron Man actor is taking his return to the Marvel Cinematic Universe for Avengers: Doomsday in an interview with Entertainment Tonight on Tuesday, March 4,.

“It’s a very intense process developing the character,” Joe said of Downey, 59, taking on Victor von Doom, a.k.a. Doctor Doom. “He’s so immersed in it. He is so dialed in.”

According to the Russos, Downey has gone as far as “writing backstory [and] costume ideas” for the villain. “I think he just loves really rich, three-dimensional characters, and I think he sees a real opportunity here with that character,” Joe added.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

At the 2024 San Diego Comic-Con, Marvel Studios president Kevin Feige shocked fans by revealing Downey would return to the MCU as one of Marvel’s favorite villains instead of reprising his role as Iron Man. Downey is set to play Doom in the next two Avengers movies, titled Avengers: Doomsday and Avengers: Secret Wars.

“New mask, same task,” Downey said as he emerged onto the panel’s stage at San Diego Convention Center’s Hall H among a group of actors wearing masks and robes at the time. “What did I tell ya? I like playing complicated characters.”

While Marvel’s Infinity Saga revolved around Thanos (Josh Brolin) as the main villain, the Multiverse Saga will debut Doctor Doom as the big bad in Avengers: Doomsday. Downey’s return to the franchise is entirely opposite of his previous Avengers character, Iron Man, who sacrificed himself to save the world in Avengers: Endgame.

Avengers: Doomsday is in theaters May 1, 2026. The movie’s follow-up, Avengers: Secret Wars, will debut May 7, 2027.