Robert Downey Jr. shocked fans and close friends alike with his unexpected return to the Marvel Cinematic Universe as Doctor Doom, announced at San Diego Comic-Con 2024. Jeremy Renner, who plays Hawkeye and is a close friend of Downey, revealed he had no prior knowledge of Downey's comeback, expressing both surprise and excitement. The original Avengers cast, including Chris Hemsworth, Mark Ruffalo, Chris Evans, and Scarlett Johansson, were also kept in the dark. Downey's return marks a significant shift as he transitions from Iron Man to the villainous Doctor Doom in the upcoming 'Avengers: Doomsday' and 'Avengers: Secret Wars,' set for 2026 and 2027. The Russo Brothers will direct these films, and Renner hinted at his own potential return to the MCU, despite recent health challenges. The secrecy surrounding Downey's return highlights Marvel's strategy to create buzz and anticipation for its future projects.