When asked about Robert Downey Jr.'s possible return to the Marvel Cinematic Universe as Iron Man, Mark Ruffalo offered an optimistic answer. Taking over the role of Bruce Banner/Hulk in 2012's The Avengers, the actors co-starred in all four Avengers films thus far. They also shared the screen in Iron Man 3's hilarious post-credits scene. While not the most prominent friendship in the MCU, the pair developed a great dynamic throughout the Infinity Saga.

https://screenrant.com/robert-downey-jr-iron-man-return-mark-ruffalo/