AceShowbiz - Joe Russo and Anthony Russo dished on the development of Doctor Doom, portrayed by Robert Downey Jr. In a recent interview with Entertainment Tonight, the described it as an "intense process."

Downey Jr., who spent a decade bringing Iron Man to life, is returning to the Marvel Cinematic Universe (MCU) in a role that marks a dramatic departure from his iconic superhero persona.

Joe Russo spoke about Downey's dedication, "He is so immersed in it. He is so dialed in. He's writing backstory, costume ideas… We were just on the phone with him this morning before we got here talking about it. He just loves really rich three-dimensional characters. He sees a real opportunity here with the character."

Doctor Doom will be central to "Avengers: Doomsday," which is scheduled for a May 2026 release. This film will also see the Russo Brothers returning to direct, following their massive success with "Avengers: Endgame."

The movie is already generating buzz, not least because of the surprise casting of Downey as the villainous Doom, a reveal that caused quite a stir at Comic-Con last year.

The casting news not only took fans by surprise but also Downey's former co-stars. Jeremy Renner, who plays Hawkeye, only knew about the casting from the media just like fans, "The son of a b**** didn't say anything to me."

"We're good friends. There's the Avengers family chat. The original six. He said not a peep. I got online and started blowing up his phone like, 'What's going on? You've been hiding this from us the whole time?' It's exciting news. I'm really, really excited about it."

Benedict Cumberbatch, who plays Doctor Strange, shared a similarly stunned reaction, recounting to Variety, "I texted, 'What the f***?' and then quickly added, 'Good what-the-f***. I mean, good what-the-f***.' "

Meanwhile, Tom Holland, known for his role as Spider-Man, was among the few who were in the know. "I've been speaking to [Robert Downey Jr.] a lot, especially about him making his [Marvel] return, which is super exciting," Holland said on the "Rich Roll" podcast. "That was a tough secret to sit on because I have a reputation for ruining things and I strategically have done no press."

As the anticipation builds, "Avengers: Doomsday" promises to deliver a riveting chapter in the MCU, with Downey's transformative role as Doctor Doom at its core.

The combination of the Russo Brothers' filmmaking prowess and Downey's versatile acting not only sets high expectations but also marks a thrilling twist in Marvel's expansive narrative universe.

"Avengers: Doomsday" is set to release in theaters on May 1, 2026.