ABC's fairy tale mash-up series Once Upon A Time is enjoying a series of heel turns in its fifth season, and from the Dark Swan on down, the shows many shadowy reveals got a spotlight Friday at New York Comic Con.

The proceedings started with an early viewing of this week's episode "Siege Perilous." The hour pushed forward the parallel quests to capture the power of the sword Excalibur while – spoiler warnings! – King Arthur was revealed to be working against the citizens of Storybrooke for his own potentially nefarious ends. Meanwhile, the Dark Swan works to find the one person who can pull the fabled Arthurian Stone from the stone by tapping everyone from Hook to a no longer dark Mr. Gold in an attempt to gain more power.

Once the episode was done, the Dark Swan herself, actress Jennifer Morrison, took the stage alongside series creators Adam Horowitz and Edward Kitsis.

"It's been a while that we wanted to [make Emma dark,]" Horowitz said while Kitsis noted that last season put them in a position to push full on into the story. "This season is more about her struggle," he said.

"It's good to be bad," Morrison said, adding "It's been a really wonderful challenge to be able to start Season 5 of a show and create something totally new. I felt like I was in a whole new show in some ways. Her struggle has been very real and very intense, and as an actor it's been great to play."

The producers said that Morrison took a heavy hand in creating the visual style of her new character. "I've been working in this business a long time, and I never felt so trusted by my bosses to participate in the creative process like this," she said. "We went through images and different fairy tales I was reading and articles I've found, and through that we built the Dark Swan."

Addressing the mind of the character, Morrison said, "Dark Emma is complicated because Emma is still the savior. It's not like she's no longer Emma. She's just the savior with darkness in her...she's in a constant battle between the light and dark within herself. Often, she's doing things for the right reasons but doing them in a dark way." For example, the character both wants Hook to be by her side as her lover, but she's also more than willing to use him to unleash the power of Excalibur.

Mystery character Merlin came up – who does appear in the show in flashback – and Kitsis said that him being a hero or a villain is not so simple. "If we think of the dark one, we know that Merlin is a sorcerer, and what we've seen through the Apprentice is that he can be a force for good."

Speaking of that line between light and dark, Regina's role as the formerly evil queen came up. "As much as she grows and changes, her past and who she was is still very much a part of her," Horowitz said. Coming up, Robin Hood, Regina and others will take on their own mission.

Also returning to the show is the series' version of Lancelot – a character who has appeared in the past in a somewhat fakeout. Next week's episode will focus on the classic love triangle of Camelot between Arthur, Lancelot and Guinevere. The producers said that the villainous Morgan le Fay will not appear in the show, but that next week's episode will go into the back story of the first Dark One who they jokingly referred to as "Steve."

The show's romances – a particular fan favorite aspect of the show came up – and Kitsis said, "Henry's will break your heart" but all the relationships will receive shakeups this season.

Princess Merida of Brave fame appears next week before taking a significant role in the November 15 special two-parter episode. It will feature a team-up between Merida, Mulan and Ruby. Also in the offing are more secrets from Hook's past including an appearance by his father and a story involving his connection to the Evil Queen.