Before sitting down to pen the script for Frozen 2, director Jennifer Lee used every creative tool at her disposal to get inside the hearts and minds of her characters. Only in this way could Lee hit on a story for a sequel worth making, that would stand up to the first Frozen.

Directed by Lee and Chris Buck, Frozen was a critically acclaimed box office smash. Winning the Academy Awards for Best Animated Feature and Best Original Song, along with countless other accolades, the film centered on Elsa and Anna—the newly-crowned Queen of Arendelle, who possesses wintry magical powers she can’t yet control, and the loving sister who sets out to save her, alongside lovable snowman Olaf, iceman Kristoff, and reindeer Sven. In the sequel, Elsa is called to the North by a mysterious voice, and the whole group sets out once again on a spectacular quest, to find the origins of Elsa’s powers, and thereby save their kingdom.

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Reteaming with Buck on Frozen 2, Lee’s mission with the film was to take her characters into a more adult realm, in which they would have to confront more serious questions about their lives. “Pretty early on, we had this beautiful roadmap that our Director of Story, Marc Smith, drew, which is, as you grow up, what you face in life—the obstacles you face, and what it feels like,” Lee tells Deadline. “I moved to New York City at the age of 21 from little Rhode Island, and the world just blew open for me. So, I think we were really modeling it after that part of life where you’re not in between anymore. You’re stepping into the adult world and finding your way.”

For Lee, the process of making the animated feature became all the more complicated last year, when she was named Chief Creative Officer of Walt Disney Animation Studios. Subsequently, she would have to figure out how to strike a difficult professional balance, completing and then promoting her film, while heading up perhaps the most reputable animation studio in the world. “I don’t recommend it,” the director laughs. “I’m only half teasing, but I think part of the thing that’s good is the way we work. The CCO is always so connected to whatever project’s up next, and that’s the priority, so there’s a balance.

“Chris and I did know how to divide and conquer, because our first Frozen, we had an 18-month schedule, from start to finish,” Lee adds. “With this, we had four-and-a-half years, [though] it still comes down to the wire. “

Below, the director expands on the process of crafting Frozen 2, her vision for the studio, and the possibilities she sees in its new streaming service, Disney+.

DEADLINE: Heading into Frozen 2, you journaled in character as Anna and Elsa, and even filled out Myers-Briggs tests for them. How did these processes aid you in developing the sequel’s story?

JENNIFER LEE: The most helpful one for me was journaling as them. A big piece of why had to do, I think, with the sequel aspect. I had done a bit of journaling for characters when I wrote in the past, but it was more important this time because we had built the first one, and it was suddenly out in the world. Over time, we’d heard a lot of feedback and ideas of who these characters are, and what should happen to them, and I found myself realizing if I was going to write further, I had to ground myself just in them, as people. And it was a really fun exercise—all of them were—because Anna and Elsa particularly came out very clear.

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They were very different; there was no worry of overlap. There was no sense of me deciding which way they should answer, or what they would say, and I think that actually gave me courage to write a sequel. I felt like, “Oh, I know them. It’ll be okay,” not knowing how hard of a journey it would be. But I still have those journals. I pulled the Elsa one out the other day and wrote a very different story, but it all ends up actually with the same themes and issues. So, that was interesting to see.

DEADLINE: You were faced with an interesting situation after Frozen became a massive hit. You’d developed characters people connected to so strongly that they really had strong opinions about them, including ones that pertained to Elsa’s relationship status and sexuality. Was it difficult to take in this investment in your work, while sticking to your guns as a storyteller, with the sequel?

LEE: Yeah. It was definitely something we had to discuss, to make sure we all felt comfortable with where we were going, because I think it’s one thing to respond, and react, and love the way the characters are being embraced and talked about. But it’s another thing to make that choice from the outside in. What we decided, really, is there are a lot of areas where we overlapped with our audience, and those were easy for us. They were clear, they pointed to something, and we weren’t afraid of those.

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But in areas where [fans] were bringing new things to it—thing we knew the character wasn’t ready to address—we knew we couldn’t do it, because it just felt like it wasn’t going to feel authentic. You mentioned Elsa getting in a relationship or not, and when I was journaling, and doing the personality and psychological tests, it really revealed that she was nowhere near ready for a relationship. Because her only lifeline to the real world was her sister. She was still shy, withdrawn, wrestling with her powers, so I knew we weren’t ready to go there with her.

The interesting thing for me would be, I haven’t sat down with her now. I don’t know who she is, where she’d go next. Someday, maybe I’ll have the courage to sit down and explore, “Okay, now she’s at one with her powers, living the life she’s meant to live. What does that mean for her?” But I don’t know if I will.

DEADLINE: Over the four and a half years you spent putting Frozen 2 together, were any screenings particularly memorable? Can you recall specific moments when you felt like the film was clicking into place?

LEE: For me, it was a wrestle many times. What was interesting is, along the way, we wrestled less with the overall story, and more with how to balance all the elements. The one that I felt was the biggest breakthrough was actually pretty significantly late in the process. There’s a moment where you look at the film you have and it is cluttered, and too complicated, and too dark, too this and that. But you look at it and you all agree what it needs; there’s no question. So, all the extra conversations of, “Can we make the character bigger and funnier?”—it all falls away.

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That was as late as June of this year, so it’s scary. If you don’t find your way in that, you know the film’s not ready. They always come together at their own pace, but I remember that moment where we reorganized how we executed the opening of the movie. We simplified the backstory, but we let ourselves hold hands on letting it be a more complex story, and letting it expand the way it did. No one was wrestling anymore; we could all see it. And I think that, for me, was when I knew, “Okay. For better or worse, this is Frozen 2. For all of us, this is what it’s meant to be.” But it took all the way till June, so it was a very hectic, very anxious summer.

DEADLINE: You’re now over a year into your tenure as Walt Disney Animation Studio’s Chief Creative Officer. What can you tell us about your vision for the studio, going forward?

LEE: I think the main thing for us is growing as storytellers, expanding on the legacy, and supporting the legacy, in ways that are timeless and then timely, and that’s always a juggle. But other initiatives for us are, we want to tell the stories of the world, by the people of the world. We want to be creating partnerships and opportunities for a diversity of filmmakers. We say this and mean this: Talent is universal; access is not. So, we work really hard to grow talent from within, and make sure we’re spotting it right—that we’re using all the tools to do that, and then finding new talent to join us. Disney+ is a great opportunity for us, growing.

You know, Walt’s big thing was always that you can’t rest on your laurels. You have to keep changing and pushing yourself creatively, trying things you’ve never tried before and being fearless, and I want to make sure we keep doing that. It’s scary taking risks. There’s no reliable formula, but at the same time, we are a studio [where] all 800 of us stay together, film after film. We push each other; we challenge each other. It’s a very unique experience. I feel very lucky. But I also know those things are how we’re going to keep being worthy of being Walt Disney Animation Studios, which means a lot to us.

DEADLINE: Could you elaborate on your thoughts, when it comes to Disney+? What opportunities do you see in the streaming service?

LEE: The greatest thing for us at Disney Animation is it allows us to experiment more with technology, and develop new talent. You know, it takes all of us to do one film a year—800 people. Most of us are working on one, and there’s a percentage on the one after that, at the same time, and that doesn’t provide for taking big risks in any other way than with that film, or with the films that are up next, or with the films five years from now. We’ve always done shorts programs and things, but that was limited, in how we could reach the world with it.

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But to have Disney+, whether it’s something from the Frozen canon or something brand new and original, we have a range of artists now. Some have just done completely original shorts, and we’re really looking to them. Are they the next generation of feature directors? Then, we have others who are inspired by something off of one of our films that already exists, and it gives a chance for them to develop that IP, and a new technology to go along with it, for real-time rendering and things like that.

It makes us stronger for our features, but it also makes us stronger because we have avenues for all the talent to reveal themselves. So we’ve been loving this. We have a Short Circuit program: Anyone can submit blind submissions, and then get to do a two-minute short. We have shorts that we have given opportunities for people to do; we’re looking at series. So, for us, the real issue is going to be a balance of time and resources, to make sure that everyone is well paced in all they want to do. We couldn’t be more excited, but it is a challenge because animation isn’t fast and it isn’t cheap. So, you have to be really thoughtful about it, and we have long-term and short-term goals that we’ll keep developing.

DEADLINE: Have you thought yet about the possibility of a third Frozen film?

LEE: I know this sounds crazy, but I’m still hoping we did right by Frozen 2. I’m still in that overwhelming position of, our kids just went out to the world. Everything feels final, but also bittersweet. Time will tell if we have more story to tell, or if anyone even wants it. So, there you have it. [laughs] Right now, I feel very done.