With Emma (Jennifer Morrison) learning the truth about her parents' past on ABC's Once Upon a Time, the threat of her turning to the dark side is more present than ever.

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Emma now knows about what went down in the Enchanted Forest with Snow (Ginnifer Goodwin), Charming (Josh Dallas) and Maleficent's (Kristin Bauer van Straten) child Lily. The show will be exploring Emma's reaction to the news, as OUAT co-creators Edward Kitsis and Adam Horowitz explained in a new TVLine interview.

"More of that is explored right from the get-go in this Sunday's episode," Horowitz said of Emma's reaction. "We're going to dive head first into what Emma has learned about her parents and how she feels about that, and how that shapes their relationship going forward."

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Emma still has the potential for darkness in the weeks to come.

"We should be concerned about the Charming family and their relationships, with this new stake of the potential for darkness in Emma," Horowitz added. "It goes beyond just your normal family spat. It's much more dangerous."

This comes amid news that Agnes Bruckner will be playing the adult version of Lily for an upcoming three-episode arc. Her time on the show will begin on the April 26 episode, suggesting that this storyline could be a driving force in the final episodes of the season.

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

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

Tags: Once Upon A Time television ABC