Even in a film as rigorously workshopped and meticulously planned as something like Star Wars: The Last Jedi, there's just no accounting for a stroke of good luck. In the face of best-laid plans, an actor could always step in and reshape the very fabric of the story. That's what happened with Star Wars newcomer Rose Tico when Kelly Marie Tran got the part. In fact, during last night's An Evening With... Rian Johnson screening of American Graffiti, the director explained how Tran's presence on the set evolved Rose from a curmudgeon to a more likable and hopeful heroine, saying:
I came up with this character of Rose and the whole idea of someone who is not the hero on the poster Her sister is like the badass pilot. She works behind pipes all day. The notion of a truly unlikely hero being kind of pushed into the spotlight seemed really interesting to me. And then once I found Kelly, I mean that whole thing of her first scene with John when she's kind of like a fan of his, and that kind of personality, I rewrote that scene before we shot it largely because of Kelly to get more of her personality into it. The character was written as more of an Eeyore type initially in the script, so she was a little more grumpy and doesn't really trust this guy. The more I got to know Kelly, she just has this open, beautiful spirit and I thought you have to see that at the beginning of this character. That's got to be what this character is about, is what she's about. It was really because of Kelly that the whole dynamic of the character changed. Thank god.
There are still definitely "grumpy" qualities to Rose (already a favorite of Johnson's before the film released) on display in Star Wars: The Last Jedi. Whenever somebody gets under her skin, she goes on the offensive. However, the casting of Kelly Marie Tran fundamentally changed the nature of the character in the sense that Rian Johnson was able to tap into an inherent lightheartedness possessed by the actress and work that into her characterization.
The result? One of Star Wars' more optimistic and upbeat characters in recent memory. Even in the face of everything bad that happens to Rose throughout the run of The Last Jedi's story, she still manages to maintain optimism that might not have been there without Kelly Marie Tran in the role.
Given what we have seen from Rian Johnson and how he goes about adding new characters to the Star Wars universe in the wake of Star Wars: The Last Jedi, it seems safe to assume that he will similarly blend script and actor moving forward. Johnson currently has an entirely new trilogy in the works that will reportedly not feature any of the classic characters that we have come to know and love over the course of the last forty years, which means he won't have any iconography to fall back in. The script and the performers who work with the script will be all he has to make it work.