Emma (Jennifer Morrison) has been told several times by other characters that she is the "savior" on ABC's Once Upon a Time, but the upcoming second half of the season may put that into question.

'Once Upon a Time's Rumplestiltskin & Queens Of Darkness Set Out To 'Corrupt' Emma?

Once Upon a Time co-creator Adam Horowitz spoke with TVLine at a screening of the midseason premiere this week about Emma and how the theme of what makes a hero and what makes a villain will apply to her as well.

"One of the big themes for the second half of the season that we want to deal with is what makes someone a hero and what makes someone a villain - what the differences are and what the common ground is. Emma has spent a long time on the series being told she's a savior and being told she's a hero. Now she's going to have to face that it's not black-and-white," Horowitz explained.

'Once Upon a Time' Bosses Talk How Cruella de Vil Is 'Delicious To Write'

There is certainly a hint that Emma may go to the dark side in a new promo released for the midseason premiere this week. The trailer featured Emma sporting a devilish look on her face while surrounded by the Queens of Darkness, a.k.a. Maleficent (Kristin Bauer van Straten), Cruella de Vil (Victoria Smurfit) and Ursula (Merrin Dungey).

Horowitz also discussed Belle (Emilie de Ravin) and how they "haven't forgotten" that she still has the Dark One's dagger.

"That's going to come into play pretty soon after our return as well," Horowitz teased.

Once Upon a Time returns Sunday at 8 p.m. ET/PT on ABC.

Watch the promo for the next episode of Once Upon a Time below:

Tags: Once Upon A Time television ABC