During the Once Upon a Time presentation at New York Comic Con, producers of the ABC fantasy drama not only gave fans a sneak peek at Sunday’s episode, but also a preview of the Frozen-centric season to come.

One of Friday’s most anticipated television panels, it began a few minutes late as convention staff attempted to accommodate as many attendees as possible (the waiting audience was treated to music ranging from Ke$ha to The Lion King soundtrack, but the opportunity for a “Let It Go” sing-along was somehow missed).

Sunday’s episode, “Rocky Road,” centers on the same freezing spell that struck Anna in Disney’s hit Frozen, but here it’s used against Marian. Everyone sets off to help in his or her own way: Emma and Charming investigate, Hook and Elsa run a side investigation of their own, and Henry, Regina and Robin try to conjure a magical cure. The citizens of Storybrooke get deeper into their season-long arcs, and the audience learns more about the show’s Frozen mythology – including what looks to be the big villain for Season 4. (No, it’s not Hans.) If the reaction in the room was any indication, Regina/Robin and Hook/Emma shippers will also be quite excited by the episode.

After the screening ended, co-creators and executive producers Edward Kitsis and Adam Horowitz joined star Jennifer Morrison, who plays Emma Snow, to preview what’s head for Once Upon a Time.

The producers revealed they won’t play with the Frozen characters in the same was they have the show’s other fairy-tale figures. “Because the Frozen characters are so new and so modern, as opposed to characters like Snow White who are 80 years old, they didn’t need any updating or twisting in that respect,” Horowitz explained. Instead, the team’s primary concern is “to be true to these characters.”

They’re also not going to tinker with the aesthetics of Anna, Elsa and company, who are fairly literally translated from their animated versions. “We didn’t want to reinvent something that was so amazing to begin with,” Horowitz said. “We wanted it to feel consistent with the movie that the whole world fell in love with.”

Still, fans needn’t worry that Frozen, or concerns for its animated follow-up, will overwhelm the series. “Whatever they do with the sequel, it’s Ana and Elsa coming to Storybrooke,” Kitsis said, “and the story that you’re going to see unfold is very much of our own mythology. As we teased tonight, it looks like the Snow Queen has a past with Emma. You’re going to see the story develop in its own Once Upon a Time way, and it’s less dependent on what their sequel would have been.”

The rest of the discussion centered on the relationships on the show and how they’ll evolve. When asked whether “Rocky Road” would be a “catalyst for [Hook’s] imminent makeover,” the creators weren’t so bullish. “I think that he’s definitely going to be inspired by Emma, but next week’s episode we are going to see a little more of the pirate side,” Kitsis replied. “I think we saw him get in Rumple’s face there, and we know that’s a man he doesn’t care for.”

Horowitz agreed, saying, “The history between those two, which is not a very pleasant one, starts to get revisited next week.”

However, there’s a silver lining, as Kitsis promised “next week will be Emma and Hook’s first proper date – and it will not be at Granny’s.”

Although the audience might have been more excited about Regina and Robin, the producers and Morrison emphasized Regina and Emma as the core of the show. “The show really did start on the conflict between the two of them, and the growing and changing relationship between the two of them,” Horowitz said, “and there is an episode coming up where we really do explore that.”

He added, “Emma believes she has to bring everyone that happy ending, including Regina.”

Morrison said she likes exploring that relationship. “They have a tremendous amount in common,” she said. “They’re women who have both made mistakes – very different mistakes, but mistakes – and struggled in different ways in their lives and have wanted to find better versions of themselves. And I think that they’re both fighting for that in different ways.”

She also said Emma has enjoyed Regina’s friendship. “Until Elsa has arrived, Regina’s been the only person she’s been able to relate to in terms of having powers,” Morrison explained. “You’re going to see Emma really fight to prove to Regina that she wants to be her friend.”

Regina herself also wants to change .She and Henry embark in “Operation Mongoose” in Sunday’s episode, a quest to find the author of the book and force him or her to change Regina’s ending. “Yeah, I would say that Operation Mongoose is going to be a rather big story for the year,” Kitsis explained. “We are splitting the seasons in half; this is a story that I think will transcend both halves.” Fans can also know that August has been ruled out. “We saw August alter the book in Season 1, but he is not the writer” Horowitz emphasized. “He gets no royalties.”

Even the happy Charmings are due for some changes. “There are some really good twists coming,” Morrison teased. “I can’t say what, but …”

Other characters, however, don’t seem as capable of change. Mr. Gold is up to his usual tricks in Sunday’s episode, and Kitsis confirmed that “everything he is doing is for a reason – and that reason is for the benefit of himself.” Belle will receive a nobler storyline, as her flashback episode will center on “why Belle became a hero.” It will also feature a brief look at Belle’s mother.

Although most of those reveals had attendees excited for the mash-up between Once Upon a Time and Frozen, fans of one character from the animated hit will likely be disappointed: The Producers confirmed that Olaf, the much-loved snowman from Frozen, won’t be making an appearance.

“I don't believe we will be seeing Olaf,” Kitsis said, to sighs from the crowd. “He may be obliquely referred to, but I don't think we will see him.”

Once Upon a Time airs Sundays at 8 p.m. ET/PT on ABC.