‘Once Upon A Time’ Season 6 Spoilers: Regina-Evil Queen Fight Continues; Emma Keeping ‘Very Big Secret’ From Hook

Regina's dark side is far from vanquished. Season 6 of "Once Upon a Time" will feature the Evil Queen unleashing her malevolent plans on Storybrooke and its inhabitants.

At the end of "Once Upon a Time" Season 5, Regina (Lana Parrilla) thought that she defeated her dark side once and for all by crushing her heart, but that's far from the truth. The Evil Queen is back and is once again dedicated to harming Snow White (Ginnifer Goodwin). Can Regina really defeat her dark side or it's a lost cause?

In a recent interview, "Once Upon a Time" executive producer Eddy Kitsis likened Regina and the Evil Queen's relationship to Jekyll and Hide. Kitsis revealed that Season 6 will explore if it's really possible for Regina to "take away" the things she hates about herself and "throw them away," or if those parts are actually a part of her that cannot be removed no matter what, TV.com reported.

Kitsis said that the upcoming season of "Once Upon a Time" will showcase "how to reconcile" both of Regina's sides, TV.com further reported. The EP noted that the mayor of Storybrooke went through plenty of character growth over the course of the ABC drama's five seasons, and she felt how to live without her dark side after defeating (albeit kind of) the Evil Queen.

"Once Upon a Time" Season 6 will show a Regina that's "excited to move on instead of always having to feel bad about the past," Kitsis shared. But her past would come back to haunt her just as she is ready to leave it behind.

And it's not just Regina who the Evil Queen would haunt. Kitsis said the heroes in Storybrooke will be "tested from their past" and their happiness and bond will be threatened by the villain, Entertainment Weekly reported.

Aside from the Evil Queen, Regina will also grapple over losing her second soul mate, Robin (Sean Maguire). Regina will grieve over Robin as she is trying to work out where she stands in Storybrooke, but the recent arrival of the refugees from the Land of Untold Stories will take her mind away from her current struggles. Together with Emma (Jennifer Morrison), they will help the new arrivals.

As for Emma, she will be keeping a "very, very big secret" from Hook (Colin O'Donoghue) starting from the premiere of "Once Upon a Time" Season 6, TV Guide reported. It's highly likely that Emma's savior status will put a wedge between her and Hook's relationship. "Once Upon a Time" Season 6 premieres on Sunday, Sept. 25 at 8/7c on ABC.