For Star Wars fans, Mon Mothma was always an interesting character — a grave, regal woman who suddenly pops up in 1983’s Return of the Jedi as the leader of the Rebellion, mourning the death of “many Bothans.” Still, she had one scene, total (as played, at that point, by veteran British actress Caroline Blakiston). So the idea that we would someday be deeply conversant with Mon Mothma’s inner life seemed about as likely as a Pinteresque drama starring the Cantina bar’s Hammerhead and Walrusman.

In 2004, the young Irish-Australian actress Genevieve O’Reilly took over the role for Revenge of the Sith, only to be almost entirely cut out of the movie. But the makers of 2016’s Rogue One honored the casting, and O’Reilly began fleshing out the character. And in the just-concluded, saga-shaking series Andor, she is essentially the second lead: We witness her destroy her life and family as she goes from quietly scheming against the Empire to open mutiny. Along the way, showrunner Tony Gilroy and O’Reilly created one of the most complex, heartbreaking characters on television. She recently sat down with Rolling Stone to reveal what it took to create this season’s award-worthy performances.

Mon Mothma agreed last season to essentially sacrifice her daughter for the sake of the rebellion by marrying her off — and at the beginning of this season, we witness that happen in great detail. How did you feel about it?
When Tony said after season one that we were starting with the wedding, I said, “Oh, my God, Tony, no. Please, we’re not actually doing this, are we?” And he said, “We’re doing it. We’re doing it.” And I’m a mother. So I was like, “Holy hell, mate. That is brazen. We’re going there.”

What’s brilliant about Tony is that he’s interested in my perspective, through the lens of that character. That is unique. So I said to him, “I really have to think on this. It’s just really bumping up against me.” And then I rang him, I think about a week later, and I said to him, “OK, I think she needs to offer her daughter an out. I think she would do it if she offered her an out.”

Oh, wow. So the scene where she tells her daughter she can cancel the wedding if she wants was your idea.
It was the two of us, because Tony straight away went, “Yeah, that’s right.” And he took that idea and he placed it at the most dramatic moment it could possibly be.

I don’t think anyone was ever expecting an extended Mon Mothma drunken dance sequence. But of course she’s dealing with the fact that she’s essentially just allowed the death of her childhood friend, again for the rebellion.
I was like, of course you would take a drink! And you would drink again. And then Tony had written in the script that she wants to feel the chaos in her body and that she becomes almost like a whirling dervish. “She spins and spins like the chaos in her head,” something like that.

I said to our choreographer, “Let’s try the whirling. Let’s see how long we can go.” And I spun and spun. They went, “OK. Let’s try it again.” And I spun and spun. And then I just had to run outside and vomit. Just threw up for real. Just ran outside and threw up for real.

Oh, no.
And the producer came out and went, “Oh, are you OK? Are you OK? Oh my gosh.” And I said, “I think we’ve solved that. We’re probably not going to be able to do that.”

So by the time we came back to do it, which was after the strike, it was almost like it was meant to be. We were so full of energy and excited about how to portray it. We had to wrestle her out of the idea of anything linear, that she had to break with whatever form we’ve ever seen Mon Mothma in before. And we had to see that chaos — yes, dancing — but that chaos in her body that we’ve never witnessed before. And it was probably one of the best days filming I’ve ever had, because Tony was there by that stage, ’cause we were back on, and we all just hit this moment at the same time and we were reaching, and it was so satisfying.

So because it was already in continuity, I guess you always knew at some point Mon was going to have to make a big, defiant speech in the Senate before escaping.
Yeah. And I think I was always driving to that moment, because that’s the central moment where you understand what she has to give — which is her voice. She doesn’t wield a weapon. She doesn’t fight in any way. The power of the voice, what you can actually risk when you dare to speak.

A speech already existed in [the cartoon series] Rebels, which I did with Dave Filoni a long time ago. So I was a bit worried that we might not get to do it in the series. But Tony came up with a way. I feel so grateful for him, for pushing the ideas that we could give that speech. It meant so much to me that there was the narrative space and the time given for her to speak and for perhaps that speech to be important.

You could say the whole show was leading up toward that episode in many ways, because, arguably, the two main threads were Cassian and yourself. And then finally after all that buildup, those two storylines finally converge.
I think so — and imagine the bravery to leave it till then!

And when you’re filming for the Senate scenes, are you just against a green screen? How does that even work?
The day we did that speech, it’s quite a lonely day actually, because you’re up on a big scaffolding where they have the pods. And then there’s just a huge, big studio with loads of green-screen around. Everyone else is a story below with a loudspeaker.

Did that episode’s script evolve at all along the way?
Tony came into my trailer one day and he goes, “So have you read episode nine? What do you think?” And I said, “I love it, Tony. I think it’s extraordinary.” And then just as I was about to speak, I was thinking, “How do I say this? How do I ask this?” He said to me, “You want me to write the whole speech, don’t you?” And I said, “Yeah, I would love for you to write the whole speech.” And so he wrote the whole speech and gave it to me.

And then the director came to me and he said, “Tony’s written you the whole speech.” And I said, “Yeah.” And he said, “We’re gonna film the whole speech.” And I said, “Yeah, that’s what we have to do, for many reasons.” And Tony knew that instinctively.

And I will never forget that moment because it’s just me up on a scaffolding and all the crew clapping at the end of it, and me almost feeling terribly emotional, really wanting it to be important. And then doing it about 17 more times. [Laughs.]

What did it mean to you to be able to deliver that and also to be able to deliver it with maximum impact and try to summon every bit of power that this character has, to explain how important objective truth is?
We filmed this two years ago. And it felt so palpably relevant then, to what we had been through in the U.K. And the idea that she could stand there and call it all out, in order to stand up for those Ghormans, the idea that she could find that bravery because of what had happened there… So to be able to deliver that speech and end with the ferocity and the passion that she did is what Tony gave to her. Tony allowed for that, and I jumped all in. I was desperate to do it.

What stands out as far as filming that escape from the Senate with Diego [Luna]? It’s definitely one of the most tense sequences in the entire show.
I remember being in Valencia in that extraordinary building, and seeing the stormtroopers arrive on foot. Running with Diego — I remember running across that high wire and having that sequence where the driver is shot. That was a really important moment actually, because I felt that it was the first moment that you could see her witnessing the impact of her voice. You see this politician who’s never actually had to look at somebody being shot before. It is probably quite a small moment, but for the two of us, it felt really important, and for me, that you saw these two people who had very different roles and therefore in that tiny little moment could behave totally differently. And he was just much more schooled in that part of what it meant.

There is that moment there where Cassian says to her, “Welcome to the rebellion.” And I remember thinking, it was such a discord for her. And yet this is when shit gets real.

How much had you and Diego even seen each other over the course of the production of the show until this moment, until this episode?
We would see each other, because we’re often running two or sometimes three units at the same time. But I remember the first day we got to step onto the set together in costume and we both just held our arms out and Diego says, “Here we are!” He is such a generous actor to work with. And so it felt really special to share the screen together after all that time.

Amidst all the drama, it should be noted you get to wear some incredibly beautiful costumes. That must have been fun.
Michael Wilkinson, who was our costume designer, is just a true artist. He is perpetually creating, working, designing. He was certainly the most collaborative costume relationship I have ever had in my career. He created, or perhaps the word is curated, so many of those costumes with me in the room, bringing different fabrics, talking me through his ideas.  The costumes, they are extraordinary. The imagination, the delicacy, the vibrancy — I’ve never experienced the opportunity to wear such pieces of art before, and I drank in every moment of it.

Diego thinks he’s done with Cassian. But in your case, it’s actually pretty likely you’ll be called upon to play Mon Mothma again. Now that you’ve elevated the character to this extent I’m curious how you feel about that.
First of all, I don’t know, ever. Let’s see how people go with this, because I am hopeful that people can see her differently after this piece. That people can look at that very big piece of work and see her and hear her differently. That would be my hope.

Yeah. Ideally anyone writing her in future adventures could build on this.
I think ambition in writing is everything. And that’s why this piece feels so special, because Tony was deeply ambitious within the writing, and therefore it allowed a platform for us all to step into, to elevate. It’s all about the writing. That’s what it comes back to.

I was thinking if you could go back to yourself in 2005 or so and explain that, “OK, you were cut out of Revenge of the Sith, but believe it or not, in 20 years, it’s going to be one of the most satisfying acting experiences of your life,” it would’ve been a very confusing conversation.
I don’t know! I was just so young. And somebody said to me, “Why do you think you were cast in it?” And I said probably because I was the palest person in Sydney [laughs].

I could have never foreseen the great fortune of this role, particularly artistically, for me. And so it feels like such a meaty piece of work. And that’s what actors strive for. You really want, not just a skeleton, but you want a person, you want to create a character with muscles and sinew and skin and freckles and everything. And I could never have dreamed that this would come from that early experience.

What a journey this has been, from that cut part to an incredibly satisfying and complex lead role that only got deeper this season. It is just such a unique path to an important performance.
Oh, thank you for saying that. I completely agree with you. It is so unique and unexpected. This is not something that you could plan for, or dare to hope for. The character, when I met her all those years ago, was quite an important expositional force within great storytelling, and then again in Rogue One, an important figure with an expositional role.

So to come now to this longform piece, to be able to be a part of something where the genre itself feels stripped away… Tony’s vision to build it from the ground up seemed like a brave idea. What he’s achieved is quite extraordinary, and I think Mon Mothma’s role in that, and my part in that, is also quite an extraordinary journey, like you said. That’s Tony to thank for that. 

Tony explained that he didn’t really know your full capabilities and was just so delighted to realize what you could bring to this. Because he didn’t cast you, you came along with the project and he was just so delighted with the whole thing.
Oh, that’s nice of him to say. Yeah. And that’s true. He didn’t. And props to Tony for really acknowledging me as an actor and even being imaginative enough to think I could do it and to work with me. That’s someone who is dextrous and nimble and curious. And he trusted me with it. I squeezed every drop I could out of it.