After a brutal hike up icy peaks to the Once Upon a Time set in Arendelle, we cornered the showrunners of ABC’s fantasy hit and demanded answers about season four’s much-buzzed-about Frozen storyline. Is Olaf going to be on the show? Are they going to give Elsa a love interest? How big a part of the show will Frozen be? And who is Elizabeth Mitchell playing, exactly? After a brief chase involving reindeers, sleighs and trolls, writer-producers Edward Kitsis and Adam Horowitz finally agreed to take our questions and give us an exclusive interview detailing their live-action take on the biggest animated movie of all time:

ENTERTAINMENT WEEKLY: Disney has been really accommodating to you in the past. But studios have historically been reluctant to let TV shows mine a current film franchise. Frozen was so huge, and there’s a possible sequel in the works. How did you convince them to let Once into this world?

Edward Kitsis: We really felt the characters would be a great fit for our show to incorporate into our universe. We really just asked, we took a shot, and we were pleasantly surprised when Disney said yes.

Adam Horowitz: There was a lot of support from within the company and we were very grateful. They trusted us with something and we take that very seriously, because it’s not just important to the company—it’s important to millions of fans of Frozen, and we want to do our best to honor what they loved about that movie, and more particularly, about those characters.

What’s your biggest concern taking this on creatively?

Horowitz: To do it justice. We would never want to re-do the movie. But we want this to feel like a part of [the movie] and feel a part of our show. We want it to walk that line of being part of the Once Upon a Time universe, but also feel like part of the Frozen world.

What was Disney’s biggest concern in terms of protecting the Frozen brand?

Kitsis: In the past, like, we made Peter Pan villainous, we’ve taken liberties with certain characters. This is a situation where everybody was on the same page. Adam and I were looking to bring the spirit of Elsa [on Once played by Georgina Haig] and Anna [Elizabeth Lail] into our show. We’re not looking to do a sequel, we’re just looking to bring them into our world for a fun story arc. So character and storywise, we just wanted to honor the characters. And with how recent the movie is, that was important to Disney as well.

Horowitz: In Once Upon a Time, we’ve approached these stories in different ways. Sometimes it’s like the Peter Pan way, where there’s a complete flip on the character and that’s our twist on it. And other times it’s about how these characters that we know fit in this world on this show—and that’s more what we’re doing with Frozen. We want to be true to the characters, we don’t want to change what they were in the movie, we want to be true to what we love about them and what everybody loves about them. Instead, we want the twist to be how they fit into our universe.

Kitsis: The entire writing staff was so inspired by this film. And thematically it’s very much within what we do—the [Frozen] curse was broken with true love’s kiss, but between sisters. And if you remember, [in] season one, we did [the curse breaking with the love] between a mother and a son. And the idea of a villain who is not actually a villain—one of the things we loved about Elsa is she went away not because she was a villain, but because she didn’t want to hurt anyone and felt different. All those themes are very related to some of our characters like Emma, and Regina and Rumpelstiltskin. It was like seeing two toys on a shelf we wanted to take off and play with.

Horowitz: From the start of Once Upon a Time we always talked about how one of the franchises on the show was love, and not just romantic love. And that was one of the things about Frozen. It was about love, but an act of true love as opposed to the traditional romantic love. We’ve tried to tell stories like that on Once, and this is what we’d like to continue with those characters—explore those ideas in that movie that we’ve already explored on Once and find a way to meet them up.

I hadn’t thought of that but you’re right—Frozen‘s twist on fairy tales is very much like what you’ve always done on this show. So were you sitting in the theater thinking, “Heeeeey, they ripped us off”?

Kitsis: No, not at all. Frozen has probably been in the works as long as our show has. We were sitting in there and just felt very inspired. The stories they were telling were ones we really respond to. We felt there was a way to do this in a fun way in our show, but not doing anything that might harm a sequel or anything they might do in the future. So fans can have fun, but rest assured we’re not trying to do anything that might harm the franchise.

Horowitz: We sometimes like to think of our show as a Disney cul de sac. You can come in, and have some fun with the characters, leave, and the characters are what you loved before.

You described Frozen as a “a fun story arc,” which suggests to me you might be thinking of this—perhaps by necessity—as more of a limited storyline within your show as opposed to the more open-ended character additions you’ve had in the past. Is that an accurate read?

Kitsis: That is absolutely accurate. It’s similar to the way we did Neverland last year, and the Wicked Witch arc.

Horowitz: We’re planning an arc involving the characters from Frozen and it also obviously involves the characters that already exist on Once, but it’s a close-ended story.

Right—but you did Neverland, yet Captain Hook is still on the show. It sounds like in this case, the characters will have a limited appearance and not be on the show in season five.

Kitsis: Yes, exactly.

Elsa didn’t have a love story in the movie, and that was part of what some really liked about her. Will you give her one here?

Kitsis: What’s interesting to us about Elsa is not who she falls in love with. Our show has always been about family. Love is our franchise, but most of our love has been about families coming together. What we love about Elsa is that she is uncomfortable with her power, she’s lonely, but wasn’t quite sure how to break that loneliness—it took the love of her sister. So we’re not interested in Elsa meeting someone, we’re interested in exploring her as a person, like we have with Regina the past few years.

Horowitz: We’re not planning to put Elsa on We’re more interested in what the movie explored, the relationship between sisters, and that relationship will be central to the story.

It’s a pretty comic movie, so I’m assuming your version will be a bit more dramatic.

Horowitz: We make room for some levity on the show, and the tone of our show can go back and forth. Comedy was a big part of the movie Frozen, and one of the fun things about the movie is how fun the characters are. We’re going to do our best to capture that spirit.

Kitsis: The humor and emotion of the “Do You Want to Build a Snowman” theme makes me cry every time I watch it, and that deep emotion is something we’d love to do on the show. If we can make you cry, we always try to. And Once, when it’s at its best, is emotional and fun.

Speaking of comedy, Olaf is a character fans really want to see. But from a drama series production standpoint, it seems like one of those things where you’d be like, “Uh, how can we ever actually pull that off in a live action show?” What are your thoughts?

Kitsis: We’re not going to. We won’t be seeing Olaf.

Horowitz: It wouldn’t fit, and it’s so beautiful, his story in the movie. The story we want to tell doesn’t involve trying to expand upon that, nor do we think it should.

Any other characters from storyline that are going to be as well?

Horowitz: We did cast Sven, but that hasn’t been announced.

Kitsis: That was an actual reindeer. That was an adventure. You don’t want to be in that casting session.

Are you doing anything different with music this season, given that Frozen is so associated with that soundtrack?

Horowitz: The soundtrack to that movie is amazing, and it’s essentially on a loop in my house with my daughters and me. I don’t think we would attempt to write our own music like that, nor do we think we could. We’ve never done a musical episode, and I don’t think the way we want to tell this story is to suddenly turn Once Upon a Time into a musical.

You already touched on this, but to make it official: What assumption should fans make about a Frozen 2? Will this narrative have any impact on those plans?

Horowitz: Anything going on with the franchise in terms of future movies is happening within the Disney corporation. We’re doing our own thing in a way to not preclude anything from happening down the line.

Though not a sequel, your arc does take place after the events in the film, right?

Kitsis: Yeah, simply because what happened in the film was so beautiful. We’re picking up these characters after the movie.

I’ve avoided asking you specific plot questions because I know that’s the area you don’t want to get into. But is there anything you’re comfortable to tease overall about how the Frozen storyline works into the rest of the show?

Kitsis: Thematically we can say the first half of the season is about how you never give up on the people you love.

So Frozen will be introduced in the premiere, and be the first half of the season roughly?

Horowitz: Yup.

There’s been a lot of guesses for Elizabeth Mitchell’s character, whether Elsa and Anna’s mom survived that sea voyage, or perhaps that she’s playing the original Snow Queen. Anything you can tell us?

Kitsis: It’s one of the two things you mentioned!

Horowitz: We’ll find Elizabeth Mitchell’s character is connected both to the world of Arendelle and the world of Storybrooke.

Since both their shows were canceled, people were hoping for the casting of Mitchell and Josh Holloway, both Lost alum, which seemed like a pipe dream. But then you cast one of them! So I should ask: Any chance of Josh joining too?

Horowitz: He’s not in mind for this particular arc, but someday, if the time were right and he were willing and we had the right thing—we’d have to have absolutely the perfect thing, and he’d have to be willing. Josh has no bigger fans than us. We had so much fun writing for him.

What does Arendelle look like in the show?

Horowitz: We’re in the process right now. We plan to show you Arendelle and plan to show hopefully, a redefinition of it that feels faithful to the movie but also feels not animated but real. That’s going to be a challenge, but one we’re really excited to try and meet.

Kitsis: This is really expensive fan fiction at the end of the day. We both have children, we love Frozen, we were so inspired by the film and we were lucky enough that Disney let us bring to life the fanfic we would normally write on the web secretly.