As many different characters hope to track down The Author on ABC's Once Upon a Time, there will be new explorations into what makes the characters heroes or villains.

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With the Frozen storyline essentially over, Once Upon a Time will now be focusing on the Queens of Darkness in addition to the quest to find The Author for the second half of season 4. Once Upon a Time co-creators Edward Kitsis and Adam Horowitz recently spoke with Entertainment Weekly about what to expect in the latter half of the season, including how various things will be revealed about major characters.

Asked if viewers will be surprised to see what side various characters are on as they search for The Author, Horowitz said, "We hope so. We hope there are a lot of surprises in this race to find the author."

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Kitsis added that it will help bring up the question of "what makes a hero and what makes a villain."

He noted that while the Queens of Darkness (Maleficent, Cruella De Vil and Ursula) will be brought in in the second half of the season, the arc will really be about the show's major, beloved characters.

"We're going to get a lot more Snow [Ginnifer Goodwin], Charming [Josh Dallas], Rumple [Robert Carlyle], a lot more Evil Queen [Lana Parrilla] and Emma [Jennifer Morrison]. We're going to see how all of this affects the people that we've come to know and love over the last four years."

Once Upon a Time returns for the second half of season 4 on Sunday, March 1 at 8 p.m. ET/PT on ABC.