Why Robert Downey Jr. Refused To Say His Original Iron Man Lines

Robert Downey Jr. may have won his first Oscar, and his Hollywood legacy may be set in stone, but that doesn't mean the man is easy to work with. On the contrary, he has a bit of a reputation for acting outside the lines — and dragging his costars with him on endless bunny trails and improvisational moments. In a lengthy interview with Esquire, Downey's Marvel Cinematic Universe co-star, Gwyneth Paltrow, even remarked that his erratic unwillingness to say his original lines eventually meant she stopped bothering to learn hers too.

"There would be this process," Paltrow said, "of [director] Jon Favreau and Robert and I going into Jon's trailer in the morning and Robert being like, 'I'm not f***ing saying these lines' and throwing them out. And then live improv-ing either in the trailer or on the set. I think in order for something to feel alive for Robert, it has to feel fresh, and he makes it fresh by making it feel like it was just invented. So many of those famous lines were written ten minutes before we said them."

Paltrow isn't alone in her opinion. The real-life Mr. Stark has inspired similar stories in his wake over the years, right up to his crowning success in "Oppenheimer."

In December 2023, Vanity Fair published a roundtable interview with several of the "Iron Man" actor's inner circle, including "Oppenheimer" director Christopher Nolan and "Avengers: Endgame" directors Joe and Anthony Russo.

Of his time spent working with Robert Downey Jr., Nolan said, "I wouldn't call them improvisations because a lot of it was very carefully planned, but he had a number of embellishments, things that he wanted to bring to the character, things that he wanted to try out." The director added, "I think he loved that freedom to move around the room and present himself with whatever energy he felt like: 'Let's try it again! Let's try it a different way!'" A little late, Nolan concluded, "So he was able to really thrash it out, really reach for something and stretch himself."

The Russo brothers, who directed Downey three times during their time with the MCU, had similar stories. "Robert is famous for throwing the plan out the window and climbing on top of the couch and whatever, sort of going off-book," Joe Russo said, before elaborating how Downey thrives the most when spontaneity is involved.

Brother Anthony added that originality helped Downey play Tony Stark for so long, saying, "Robert has certainly lived a complicated life. He understands the stakes, he understands loss, he understands the turns life can take between ups and downs. He's always looking for that level of depth, that level of complexity. I think he knows that's what we all come to movies for in the first place."

Throughout his MCU tenure, Robert Downey Jr. was busily rewriting his scripts. The man famously brought his "I love you 3,000" line directly from the homefront. "Endgame" co-writer Christopher Markus has gone on record saying, "Well, as much as we'd like to take credit for what is inevitably going to be one of the most memorable lines in MCU history, that is something that Robert and his children actually say to each other. He brought it from real life onto the set" (per Fandango).

One line that Downey did say verbatim was his last as Tony Stark. During principal photography for "Avengers: Endgame," Downey didn't say his epic final line as he wiped Thanos and his army out of existence. The actor lobbied for a reserved reaction from Tony Stark as he finally faced his mortality. However, directors Joe and Anthony Russo decided he needed to say something. When they came up with the fateful final line, "I am Iron Man," they knew they had to bring the actor back to reshoot the scene — even if he didn't want to say the line. Despite his misgiving at revisiting the character after such an emotional departure, the MCU legend returned. Downey nailed his emotional final day on set, and the rest is history.

If you'd like to learn more about one of Marvel's greatest heroes, check out the untold truth of "Iron Man."