Kitsis & Horowitz Unleash A 'Frozen' Crossover For 'Once Upon A Time's' Season Premiere

While they probably won't appear belting mega hit "Let It Go," the characters from Disney's blockbuster feature Frozen officially arrive on sister company ABC's Once Upon A Time this Sunday at 8:00 p.m. E/P.

And while Once has trafficked in fairy tale crossovers from the opening moments of its first season, the sister princesses Anna and Elsa (played on the show by Elizabeth Lail and Georgina Haig) and the rest of their Frozen friends (like Jonathan Rhys-Davies as Pabbie and Tyler Jacob Moore as Prince Hans) will play a different role in Season 4. Well aware of the attention the cast is bringing to their series, show creators and executive producers Eddy Kitsis and Adam Horowitz have plans to drop the icy newcomers into Storybrooke's existing canon without rewriting the rulebook of either world.

With Season 3 wrapping a major arc for core characters like Emma, Prince Charming, Snow White, Rumpelstiltskin and Regina The Evil Queen that left some in love, some in conflict and some just exhausted, the stage is set for a wintery shake up. Spinoff Online spoke with Kitsis and Horowitz about the season premiere ahead of Sunday, and the pair explained how Anna and Elsa's appearance was a surprise victory for the show, why the characters won't change from their screen counterparts even as Storybrooke does and how the arc of the first eleven episodes brings a new mystery and a shadowy villain to the stage.

Spinoff Online: Guys, it's almost prophetic what happened just before this call. As I was waiting for you to come onto the line, the hold music was Radio Disney blasting "Let It Go."

Eddy Kitsis: [Laughs] I think they might have it on an endless loop now. That's all they play for the hold music.

So how did Frozen come to Once Upon A Time? Did you see the movie and immediately want to bring it into the writer's room?

Kitsis: Yeah. We all first saw it when it came out last November, and Adam and I really, really responded to it. They had frozen hearts, and we rip them out. Their act of true love was between sisters, and our Season 1 broke it between a mother and a son. And we were really inspired by the storytelling and the tone, and in the room we just started talking about it as a collective. Like writing rooms do, you talk about the think that everyone's just watched. And we started saying, "What if they were on our show? Wouldn't that be cool?" By some time around January or February, the room started to have really solid ideas on what we would do if we could bring a couple of those characters into our world. We went to Disney expecting a "No," and we were pleasantly surprised when we got a "Yes."

So is the pressure on considering how massive a crossover hit that movie became?

Adam Horowitz: It's fun and daunting. It's always fun to see characters come to life and to see what amazing actors can bring to them. But at the same time, these characters are iconic roles that we're trying to fill. We were very fortunate to brings some great performers on.

Kitsis: Yeah, once we got that "Yes" we were like, "Uh oh. It's Frozen." We felt a responsibility to be really true to the movie and do our best in finding people who would bring these characters to life in a fun way.

Last season of the show was a big journey for the weird extended fairy tale family that is the core Once cast where they went to Neverland and back. And I feel like they ended at something of a stable place. Does the Frozen cast essentially provide way for you guys to shake the show back up some?

Kitsis: Yeah, for us this is really about the characters of Frozen coming into Once Upon A Time. For the Once fans, we pick up exactly where we left things off last year. Marian came back to interrupt Robin Hood and the Evil Queen. Emma has just taken a step forward with Captain Hook. Emma as a character has started to embrace her role. She's said, "This is my home, and I know who I am." So everyone was kind of starting over – some people in better places than others. We know that Rumpel is lying to Belle, for example. So Elsa is definitely come into Storybrooke and shaking things up.

The story that we're telling for this first eleven episodes – because like last year, we're splitting the season in halves – starts with the premiere like a mystery. Elsa brings a mystery to our characters, and we go from there.

Every year I know you step into the season with one goal, and while the mystery part of that may be exactly that, did you have a theme to explore with the characters overall?

Kitsis: Yes. One of the things that we were so inspired by in Frozen was that we loved the character of Anna. It was the fact that she never gave up on Elsa. Everyone else thought Elsa was scary and a villain, but Anna never gave up on her. So for us, the theme for the first half of the season is "Never give up on the people you love."

While a lot of the characters coming in new to the show this year are fan favorites, you've also announced a number of villains including Prince Hans played by Tyler Jacob Moore and another unknown character. With that one player shrouded in mystery themselves, is this first eleven episodes driven in part by that big bad's identity?

Horowitz: One of the things about the Frozen characters coming on is that we're not changing the essence of these characters. That's not what we're interested in at all. So you've got Anna and Elsa and then the villain – which is to say that there is another villainous presence that will rear its head quite quickly at the start of the season. We're excited to unleash that on the audience, and hopefully show a fun twist on both our story and the Frozen story.

Looking at some of the particular Once characters heading into Season 4, it seems Regina has gotten to a place that's a little more empathetic and a bit more on the side of the rest of the Storybrooke gang. But I also know people love it when she really plays the villain. How do you ride that line moving forward?

Kitsis: We do ride that line, and we spent most of last season wondering whether or not we can expect the truth from her. With Marian entering at the end of the season, it'll relate to that. The premiere absolutely deals with her in that way. There are characters who you want to see be bad and characters you want to see do good, but the truth is that we're in Season 4 and what you have to do now is figure out a way to earn those changes. Right now, Regina's on the path to redemption. As fun as it is to see her be the Evil Queen and act completely horrible in flashbacks, I think there's also a sense of fun in seeing her evolve as a person. But with Rumpel and with her, you always love it when those actors can find that inner darkness.

And I'd say that also goes for Captain Hook. I think we're going to see some rivalries rear their heads this year – especially the old Hook and Gold rivalry.

One piece of info on how this season will be working on the world-building front is that Elsa and Anna will not be connected to the original group of characters in terms of their pasts connecting or being affected by the spell that set the whole series off. How does that impact the series approach of tying all these disparate characters together through their pasts?

Horowitz: There certainly are some nods and explanations about some other smaller characters who will make brief appearances across the season. We love that mash-up quality of the show and intend to keep playing with it.

You're also bringing in Jonathan Rhys-Davies who is known for so many fantasy and adventure crossover hits in as Pabbie. What does such a memorable voice bring to the cast as a guest star?

Kitsis: Right when we see Jonathan, he's in troll form, so it really is his voice. And that's fantastic because he brings such a weight and a depth to the roll. When you hear that voice for the first time – just like we heard it in editing – it's great because you see the character and how he interacts with the Frozen world, and it's so cool. The great blessing of our show is that we've been able to cast great actors. That's what make this all work. It's great to be able to write for Jonathan or Robert Carlyle or Ginnifer [Goodwin]. For us, we just want to tap the best actors coming in and unleash them on the world.

I know last year you had the spinoff Once Upon A Time In Wonderland which also used a lot more CG for characters than you had in the past. Has the learning curve improved in terms of big fantasy imagery you can pull off thanks to that?

Horowitz: After many years of the show, we've learned a lot through trial and error of what works well and where the places are that we can push things effects-wise. We've very excited to push the boundaries of what we've accomplished in the past this year. There will be some spectacular things to see.

And I'm sure it's a task in and of itself to make the world look like it's covered in ice and snow right now.

Kitsis: It really does! [Laughs] We keep joking that we've been doing Frozen in July in the sunniest part of Vancouver. But we have learned. Some things have worked better than others, but we always want to push the envelope and not limit our vision because the internet might get upset that a certain background didn't look real enough.

So for the mystery of everything moving forward, what's the most important detail from the first episode people should look for?

Kitsis: I'd say that the detail in terms of what will transcend both halves is to pay close attention to Regina and what she's talking about. And I'd also look out for a rather iconic artifact that Rumpelstiltskin is going to come into contact with.

Once Upon A Time's fourth season premiere bows Sunday at 8:00 p.m. E/P on ABC.

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