The season 4 finale of "Once Upon A Time" saw Emma Swan (Jennifer Morrison) getting turned into the Dark One in order for Regina (Lana Parilla) to have her happy ending. Prior to turning dark, however, Emma showed that she was through and through, a savior, making the ultimate sacrifice. It would be an interesting dynamic to see Emma being dark and Regina potentially being the good one in Season 5. As to Regina's happy ending, it is not a certainty, as Zelena (Rebecca Mader), the Wicked Witch of the West, is still hell bent on keeping Robin Hood (Sean Maguire) and Regina apart and of course they have to deal with Zelena's pregnancy.

There are speculations that Zelena will play the big villain in season 5. Josh Dallas, who plays Prince Charming told fans in an interview with Spinoff Online, "The new big baddie is going to be really bad. It's the unimaginable. It's the worst thing that could possible happen. It's going to be tough from everybody. It's going to be distressing for fans."

Merlin will play a key role in Season 5, as he will be the only one that could banish the evil from Emma's soul. The search for Merlin will be an integral story arc. There is no word yet as to who will play this part.

Another big change in season 5 will be the story of Rumplestiltskin/Mr. Gold (Robert Carlyle). Henry (Jared S. Gilmore) did become Rumple's undoing, as was prophesied. Henry reversed the pro-Rumple story that was written by Isaac Heller (Patrick Fischler), the Apprentice, thereby removing the darkness from Rumple's heart. Rumple also has to deal with his relationship issues with Belle (Emilie de Ravin).

Emma's going dark will affect her parents, Snow/Mary Margaret (Ginnifer Goodwin) and Charming/David (Dallas), as it would her son Henry, who had become The Author. Obviously, it would affect Killian/Captain Hook (Colin O'Donoghue) as well.

There is no word yet whether Maleficent (Kristin Bauer van Straten) and her daughter Lily (Agnes Bruckner) would play any key roles in the new season. "Once Upon A Time" Season 5 will premiere on ABC in the fall.