Regina (Lana Parrilla) has always been her own worst enemy on Once Upon a Time, and that will take on a literal meaning this season as she goes toe-to-toe with her alter ego this fall.

The mayor of Storybrooke thought that she had vanquished the Evil Queen once and for all at the end of last season, but her other half survived the heart crushing and is now ready to fulfill all of her nefarious plans. We know the Evil Queen is setting her sights back on Snow White (Ginnifer Goodwin), but Regina could be the only one who can stop her. The question is, can Regina get rid of her dark side once and for all?

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"What we're really going to be asking ourselves — and Jekyll and Hyde are the perfect metaphor — is can you really divide the dark side of yourself? Can you really take the things you hate about yourself and throw them away or is that actually a part of who you are?" asks executive producer Eddy Kitsis. "We have to figure out how to reconcile both sides. That's kind of what we'll be exploring this year."

It will take some time before Regina will realize that squashing the Evil Queen's heart didn't do the job, which allows the former villain to at least know what it feels like not to have her darker self raging inside of her.

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"She's really done a lot of character growth over the five seasons. She's really become a different person. We're picking up from that," Kitsis says. "Internally, we're going to see a Regina that has a weight that's been lifted off her, a Regina that's excited to move on instead of always having to feel bad about the past. Unfortunately, when you try to leave your past behind you, it rears its head again."

The Evil Queen won't be the only thing haunting Regina though. She'll still be healing from the loss of Robin (Sean Maguire) and trying to figure out her place in Storybrooke now that she's lost her second soulmate. Luckily, the new arrivals in Storybrooke from the Land of Untold Stories might help distract her from the pain.

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"She's clearly very much grieving Robin and we're going to see that in the premiere," Kitsis explains. "Hyde hinted last year that there are people in the Land of Untold Stories whose stories haven't played out. We're going to find ourselves in a situation where Mayor Regina and Savior Emma are going to have to help a whole bunch of people find their happy endings as well."

How do you think Regina will fare against the Evil Queen?

Once Upon a Time returns Sunday, Sept. 25 at 8/7c on ABC.