The actor, who made his exit from the MCU in the record-breaking Marvel blockbuster, is known to be a strong improviser on set, and it seems his initial showdown with Steve Rogers (Chris Evans) in Avengers: Endgame was when those skills came in handy once again. That scene, set soon after Tony Stark and Nebula (Karen Gillan) returned to Earth, showed him lashing out over feelings of betrayal – fiercely calling Steve a “liar”.
This scene, it seems, was largely improvised by Downey Jr.
Anthony Russo told Empire: “I think that was one of Downey’s most inspired performance moments in the movie.
“He very much reverts to, this is the guy who felt forsaken by his father – you can see his intimacy and trust issues in that moment when he turns on Cap.
“Downey performed the scene with a lot of energy.”
The film-maker added: “We didn’t do it many times, because he was expending himself so, so much. He understood it very well.”
Also speaking to the magazine, writer Christopher Markus spoke about Marvel’s attitude towards Tony’s ultimate death on the battlefield.
“Marvel as a whole said, ‘We think it might be a time [for Tony to die], but if you have a good reason not to do it, feel free – we’ll do whatever’,” he recalled.
“But it really did seem like, particularly with what Tony experiences after the five year break – that he has gotten married, had a kid, and is living a very healthy, peaceful life for once, and he’s had five full years of no surprises – that there wasn’t anywhere left that he needed to go.
“This was a guy who had made his full journey, all the way to the end, had experienced a full rehabilitation of his character from being the douchebag in the back of the Humvee at the beginning of the first Iron Man.
“To have him make the sacrifice that Steve Rogers would have made had he had the opportunity at that moment, just felt really right.”
Chris Evans, who played Steve, is also thought to have left the MCU.
Avengers Endgame is out now.