What Makes Once Upon a Time's Wicked Witch So Wicked? Plus: Who's Dorothy In this Story?

When Once Upon a Time resumes its season on March 9, the ABC drama will commence its first dive into the stories of Oz — including the introduction of a witch who is so wicked partly because the character is, as one cast member puts it, “so damn likeable.”

Make no mistake, Rebecca Mader‘s Wicked Witch — as seen in the fairytale land portions of the coming episodes — is unabashedly abominable. (As she snarls to a minion in the midseason premiere, “I’m wicked, and wicked always wins.”) But as revealed by ABC’s synopsis for the second half of Season 3, there remains a Storybrooke component to the storytelling. Because although the fall finale ended with the Maine burg vanishing from existence (as Regina, Snow White et al were returned to the Enchanted Forest), mysterious circumstances restore Storybrooke and much of its population — the Wicked Witch’s “kindly” alter ego included.

In her Storybrooke form, the witch “is seemingly a kindred spirit to Snow White, which is part of what makes her so evil,” Ginnifer Goodwin explained during TVLine’s visit to the show’s Vancouver set last week. “She seems so genuinely kind and has a way of becoming intimate with others and making them trust her…. Rebecca Mader called her ‘Mary Poppins,’ because she was just so damn likeable!”

Goodwin credits Mader for that wicked wrinkle, explaining how the Lost alum tweaked her Storybrooke persona while rehearsing her first such scene. “She wanted her to be manipulative and conniving, something of an investigator,” Goodwin relates. “But then she realized, ‘No, what would actually be wicked would be to match Snow’s sweetness and really seem like someone cut from the same cloth.’”

So good is Mader at being so bad, Goodwin said with a laugh that she and others will at times witness a scene and find themselves wondering, “Is it bad that in some respects we want her to win?!”

Of course, if you bring on a Wicked Witch (and, ultimately, a good one), it stands to reason that somewhere in this Oz-some arc, there must be a Dorothy. Could that role be filled by Emma, who for the past year has been living with Henry in New York City, oblivious to her fantastical origins or their Storybrooke days? If a certain pirate can somehow find a way to convince Emma of the unbelievable truth?

“I think so…. Eventually,” Jennifer Morrison offers. “I’m not sure, but… a lot of this is about Emma accepting Storybrooke as her home, so I think that’s where the Dorothy theme will come into it, that ‘there’s no place like home.’”