Season 5 of ABC's Once Upon a Time will largely be about facing your inner darkness - at least when it comes to Emma (Jennifer Morrison) and Hook (Colin O'Donoghue).

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Morrison, O'Donoghue and many of their other Once Upon a Time costars appeared at a Comic-Con panel on Saturday. They teased what's ahead for season 5, particularly in the Emma darkness storyline.

As fans know, Emma sacrificed herself to contain that darkness in the season 4 finale, and she subsequently got swallowed up by it, leaving behind only the dagger with her name on it. Now that Emma has turned to the dark side, she will be coming to grips with an intense inner struggle.

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"Emma went through a lot in her life," Morrison said at the panel. "She had a tough childhood. She's had to overcome a lot of things. She's tried to be the bigger person. Now that she's tethered to the darkness, she's free of that ... She's going to face the darkness in herself and figure out how to overcome it."

As for Emma's counterpart, Hook, he obviously has a past as a villain so Emma's darkness will be tough to deal with.

"He found love with Emma," O'Donoghue explained. "He has been a villain, but his girlfriend is nasty now, so who knows what's going to happen?"

And of course for Rumple (Robert Carlyle), he will be a changed man now that he is no longer "the Dark One," as Carlyle explained himself at Comic-Con.

"The incarnation of Rumple this time around is slightly different," he said. "He's lost his mantle as the Dark One, but that's not to say he doesn't have that trickery about him. He still has that. Mr. Gold is presently in a coma, so he's not doing too much."

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

Tags: Once Upon A Time television ABC