Jon Favreau recently revealed his method for creating the first Iron Man movie’s dialogue and it proves how lucky the MCU was to have this cast.

Iron Man director Jon Favreau recently revealed his trick for writing dialogue in the first MCU movie, and his method showed just how important it was that the movie had the right cast. It may be hard to remember, given what an icon Robert Downey Jr.’s Tony Stark became, but at the time Iron Man seemed like a big risk. Iron Man wasn’t as popular as heroes like Spider-Man, and Robert Downey Jr. had only recently started his acting comeback. This is likely why Marvel had originally thought of having Tom Cruise attached instead, given his star status.

Having seen Iron Man and the subsequent MCU films, it’s hard to imagine anyone but Robert Downey Jr. in the title role. His charisma helped carry the MCU timeline for over 10 years. Now, with Jon Favreau’s recent reveal about the original Iron Man, it’s clear that Robert Downey Jr. and his co-star Gwyneth Paltrow were even more instrumental to the movie’s success than may have been previously thought. In fact, it’s quite possible that, without them, the movie would have been very different.

Iron Man Writer/Director Jon Favreau Used RDJ & Gwyneth Paltrow’s Real Conversations In The Movie

In a recent interview with People, Jon Favreau revealed that he would take notes on the real conversations Robert Downey Jr. and Gwyneth Paltrow would have behind the scenes, and integrate that into the movie’s dialogue. Favreau gave an example of one line he lifted directly from Gwyneth Paltrow, saying:

“Gwyneth corrected him once because we were reading the script and it said, ‘This looks like Jackson Pollock’s spring period,’… So I wrote down every word, and she’s correcting him in the movie when he says, ‘the spring period.’ So it just adds to their sort of nippy banter.”

Favreau credits these types of moments as contributing to Tony Stark and Pepper Potts’ on-screen chemistry. As two characters with one of the most integral relationships in the movie, anything that added to their dynamic went a long way toward making Iron Man the success it became.

Favreau’s comments about how Tony and Pepper’s relationship was in part due to Robert Downey Jr. and Gwyneth Paltrow’s real conversations make it even more clear that the pair were integral to the movie’s overall quality. Had actors without as much natural chemistry and distinct personalities been chosen, Iron Man‘s dialogue could have felt much less engaging, and the whole movie may have fallen flat. A different cast could even have impacted the entire MCU.

Why The MCU Probably Wouldn’t Exist Without Iron Man’s Success

Marvel was in a pretty tumultuous spot when Iron Man first came out. This was before Marvel was bought by Disney in 2009, and it’s unlikely Disney would have shelled out $4 billion dollars to buy the company had Marvel not just hit it big with Iron Man. While Marvel had already been planning the other early MCU movies when Iron Man came out, it’s not hard to imagine the entire MCU falling apart had Iron Man been a total flop.

Thanks to the success of Iron Man, Marvel made itself a valuable enough property to be taken over by Disney. This gave Marvel Studios the financial backing required to continue making high-quality movies, and establish a firm base for the MCU. Robert Downey Jr.’s Iron Man also gave the universe a very strong personality to center itself on in the early years as Marvel built up its roster of characters. Without his and Gwyneth Paltrow’s contributions to their Iron Man characters, the MCU might have never become what it is today.