The arrival of Elsa and Anna from Frozen in Storybrooke was the focus of the Once Upon a Time panel at Comic-Con International in San Diego.

To answer how ABC’s fantasy drama decided to showcase the Frozen characters in Season 4, executive producers Adam Horowitz and Edward Kitsis introduced a hilarious video of the writing staff during its annual brainstorming session, jokingly referred to as “mini-camp.” The writers pitched ridiculous ideas, arcs and villains that weren’t suitable, well, for any show, really. As a last resort, they pulled out a red Dharma Initiative phone that gave them direct access to Lost co-showrunner Carlton Cuse, who didn’t pick up.

“They’re on their own,” he quipped. “Fuck ’em.”

Ultimately, a pizza delivery boy suggested Frozen would be a good for the series.

Later on, other footage from the Season 4 premiere featured Anna (Elizabeth Lail) and Elsa (Georgina Haig) standing in front of their parents’ gravestones. The conversation quickly turned to Anna’s impending wedding, for which Elsa promised she had a big surprise planned.

Another video clip focused on Regina (Lana Parrilla), who might be reverting to her wicked ways. She opened the door to a cell where her magic mirror had been locked away. “There’s someone standing in the way of my happiness,” she said menacingly. “I need your help getting rid of them.”

Besides Horowitz and Kitsis, the panel consisted of cast members Parrilla, Josh Dallas (Prince Charming), Colin O’Donoghue (Hook), Jennifer Morrison (Emma), Jared Gilmore (Henry), Robert Carlyle (Rumple) and Emile de Ravin (Belle). The rest of the time was spent answering questions from moderator, and Community star, Yvette Nicole Brown, as well as the audience.

In the Season 3 finale, Rumple duped Belle by giving her a fake dagger that would control him. Asked whether the end justifies the means, Carlyle replied, “I certainly hope so. I think those storylines have a long way to play out. I think the dagger may come back again, get lost again and come back again. It’s difficult for Rumpelstiltskin. He’s such a complex kind of guy and character, and he’s an addict. He’s addicted to power. He’s addicted to magic and finds it very difficult when he loses. It’s very difficult to shake that and break that, but that’s what he is.”

As for how Belle will react when she finds out about Rumple’s deception, de Ravin said, “I think she’ll be quite devastated, but once again I think we’re gonna try to turn it into [turning to Carlyle]. … Maybe you will turn it into a different situation to validate yourself. You’re trying to protect me and maybe I’ll believe that.”

The Season 3 finale also found Emma bringing Marian (Christie Laing) from Fairy Tale Land to Storybrooke. That reunited Marian with her missing beau Robin Hood (Sean Maguire), and also potentially put the kibosh on his blossoming romance with Regina. Morrison chimed in on how this unfortunate development could affect Emma’s relationship with Regina. “I can’t apologize for saving a life, and I’m also horrified that got in the way of Regina’s happiness,” she said. “Then there’s also the story that this might spiral her back to some of her old ways. And because she has come so far and we have all grown together so much, I think Emma will be very determined to try to keep Regina in a good place in her life. And to try to keep something positive between us, so it’s been cool. It has a really nice element of conflict and concern and generosity between us, in the sense that Emma really wants to keep her in a good place.”

Whether a hurt Regina would become evil again out of revenge, or to get what she wants, was addressed by Parrilla. “I think she has something up her sleeve,” she said. “Not surprised. I think she’ll be conflicted. She enjoyed being good, like she enjoyed discovering the light magic that she possessed. However, old habits die hard.”

Other tidbits that were revealed during the panel include:

• Henry will bond with Rumple.
• O’Donoghue will trade his 50-pound leather Hook costume for snazzier threads
• Neal/Baelfire (Michael Raymond-James) may be dead, but he could return in flashbacks
• Michael Socha, who played Will Scarlet/Knave of Hearts on the spinoff Once Upon a Time in Wonderland, will become a series regular

Once Upon a Time returns Sunday, Sept. 28, at 8 p.m. ET/PT on ABC.