The co-creators of ABC's Once Upon a Time revealed a whole slew of details regarding season 5, particularly involving Emma (Jennifer Morrison) and her darkness.

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Once Upon a Time co-creators and showrunners Edward Kitsis and Adam Horowitz spoke with fans at D23 over the weekend. The discussion featured the show bosses teasing several new pieces of information about the upcoming fifth season.

Addressing Emma succumbing to the dark side in the season 4 finale, the co-creators discussed how she will be a different kind of Dark One than Rumple (Robert Carlyle).

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"Being the 'Dark One' is like putting a magnifying glass up to who you really are and then twisting it a bit," Horowitz said, according to Comic Book Resources. "Emma will definitely be different from Rumple."

"Having the dagger and the power that comes with it tricks you into believing that there is a freedom to lose your fears," Kitsis added. "We [the viewers] know who Emma is and what her fears are, so there is a different take on the 'Dark One' with her."

Those around Emma will be greatly affected by her darkness. Her mother Snow (Ginnifer Goodwin) will especially take it hard. Goodwin, who was also at the event, explained:

"The darker Emma goes, the more to Snow/Mary Margaret she is herself a failure."

Ultimately, the first half of season 5 will have darker themes than those in season's past.

"The first is 'sometimes things aren't what they appear to be,' and the other is 'love is a very dangerous weapon,'" Kitsis said, of the two themes present in the first half of the season.

Once Upon a Time season 5 premieres Sunday, Sept. 27 at 8 p.m. ET/PT on ABC.

Tags: Once Upon A Time television ABC