Once Upon a Time co-creators Adam Horowitz and Eddy Kitsis shared that they had thought about the twist for a bit, but first wanted to put Emma through the trials she went through last season: get the warning, fight against it and still opt to make the sacrifice.
With the extra time to prep, the creators and Morrison were able to collaborate on Dark Swan's very distinctive look. "I've never felt so trusted by my bosses," Morrison said. "We spent a long time going back and forth through images [and pieces of writing]… we picked out the things we loved, and from that, we built Dark Swan."
As the show explores Dark Swan, Emma's savior status is still intact; it's just ... complicated. "Emma is still the savior," Morrison explained. "It's not that she's not Emma. She's the savior with darkness in her. Emma is a constant cauldren of conflict. She's in a constant conflict with dark and light ... [and sometimes] doing things for the right reasons but doing it in a dark way."
Looking ahead, the show will do a two-hour episode in November, and part of it will be an adventure featuring Merida (Amy Manson), Ruby (Meghan Ory), and Mulan (Jamie Chung). Another unlikely duo teaming up? Hook (Colin O'Donoghue) and Regina (Lana Parilla).
The creators are also they are looking to cast Hook's father for an upcoming episode. (They were, however, mum about whether Emilie de Ravin's real-life pregnancy will be written into the series.)