After vanquishing Peter Pan, defeating the Wicked Witch and grieving over the death of Baelfire, surely the residents of Once Upon a Time’s Storybrooke deserve a break. Wishful thinking.

As the season finale teased, and the ABC marketing machine promoted all summer, Frozen’s Elsa will make her chilly presence felt in the fantasy drama’s fourth season. However, that’s only the tip of the iceberg.

Following the Once Upon a Time panel at Comic-Con International in San Diego, members of the cast, as well as executive producers Adam Horowitz and Eddy Kitsis, participated in roundtable interviews with the press to discuss the show’s twist on Frozen’s Anna and Elsa, Regina’s moral compass, and whether love truly conquerors all.

Lana Parrilla (Regina/the Evil Queen)

Regarding Regina’s struggle to remain good: Regina has her plans, but she’s not quite sure how they are going to unfold. It’s like a game of chess: She’s setting up all the pieces and then she’s going to wait on what that next move is. Everything is lined up to make that next move. We are only two episodes in, so there’s not much to say. I think she’s teasing and playing with the idea of being evil again, but it may not be in the same ways that we’ve seen her before.

On Regina and Elsa’s lack of history: Regina has nothing to do with that. She never opened the time portal. She never traveled through time. This is not her fault, like most things are. She is unaware of who this Elsa is. They’ve actually not met. I have yet to meet the actress. Georgina [Haig] is playing Elsa. Our storylines don’t cross paths.

Jennifer Morrison (Emma Swan)

How Emma relates to Elsa and Anna: It’s interesting with how many different ways it reflects with what’s going on in Storybrooke. There’s a little bit of Emma trying to keep Regina from going to the dark side, which is a little bit like Anna trying to get Elsa to reconnect with her. There’s some stuff between Hook and Emma that is very Kristoff/Anna-ish. It’s all been very fun. They’ve really joined the show in a way that feels so natural, that feels like they’ve always been there.

Josh Dallas (David/Prince Charming)

On Charming’s arc this season: You will find out things about Charming’s past, that he has a friendship with a character that you wouldn’t necessarily put with Charming, who basically changes the whole course of his life.

On the father/daughter dynamic between Charming and Emma: You’re going to see that relationship grow as we see the similarities between the two. Emma and David are very similar in many ways. That’s going to play out a little bit too, particularly in the first part of the season.

Whether Dallas will be getting more action: Yes, in the second episode there’s sword fighting. I actually have stitches in my finger right now. My knuckle got exploded by a sword. People will say, “What did you do?” I say, “Sword-fighting.” They are like, “Bullshit.” “No, really, I was sword-fighting.” So, yeah, you’re going to see a lot of sword play.”

Robert Carlyle (Rumplestiltskin/Mr. Gold)

Whether Belle is safe with Rumple: I don’t think anyone is. The problem with Rumple is he’s an addict. He’s addicted to the dagger, the power, the magic or whatever it is. He’s been practicing that for hundreds of years. I don’t think he means the things he says. He loves Belle more than anything. On the other hand, a leopard doesn’t change its spots overnight. I think this relationship has a long way to go.

Where Rumple and Belle stand early in Season 4: It’s not good. There’s already been a relapse for Gold. He’s digging a hole even deeper for himself. This season will stretch their relationship to its absolute breaking point. It will be interesting to see whether they can actually live with each other or without each other.

Edward Kitsis (executive producer)

Regarding why the Frozen characters are such a good fit for : They broke their curse by true love’s kiss between two sisters. Our curse was broken by a mom kissing her son. They had frozen hearts and we rip them out. We thought Elsa had a lot in common with both Regina and Emma. Anna had a lot in common with Snow White. Thematically, we just felt it was a perfect fit. They were two empowered female characters that we really wanted to write for.

On whether Anna and Elsa interact with all the characters: We aren`t trying to do the Frozen sequel. We’re saying, “What happens when Anna and Elsa come into our world? And do they have any past history with anyone from our Once universe?” For us, it’s really exciting. What happens when Anna, who is this character who never gives up on the people she loves, is so hopeful and sees the good in everything … What happens when she meets Rumple, who is the devil himself? What happens when Emma and Elsa actually talk about the fact they both have magic they can’t control, that they feel different from everyone else? That it’s really hard to let people in? Those are the things that excited us.

Adam Horowitz (executive producer)

On pushing Regina to her limits: She will definitely be tested in the premiere, and it will be hard for her. The Robin Hood/Regina story is one of our favorites.

It’s really great watching Regina grow and being able to drop something. If we did this in season one, we know what would happen to Marian. If it happened in season two, it would maybe have been even worse. For season three, we’re not quite sure. What’s fun in season four is watching the growth of that character. She’s earned everything she’s had. Does she let it all go or does she keep working towards something even better?

Concerning the first arc’s mysterious new threat: We do have a big bad. We want it to be a surprise. We can tell you it’s not Elsa. There’s something else at play that becomes apparent pretty quickly once the season starts. Part of that is because Elsa is not a villain and Anna is not a villainess. What we’re really interested in seeing is the challenges they face with our characters.

Once Upon a Time returns Sunday, Sept. 28, on ABC.