"Once Upon a Time" season 5 will debut in just a few days, which means that fans of ABC's hit supernatural fairytale thriller will finally see how Emma (Jennifer Morrison) will turn into the Dark Swan. 

At the end of the fourth season, Emma sacrificed herself to save Regina (Lana Parilla) from being completely consumed by the dark side. This means that someone should step up to become Storybrooke's hero – at least for the meantime. 

Surprisingly, the one expected to fill in Emma's role is the Evil Queen herself. But is Regina willing to undergo a role reversal? 

"Regina is going to be the hero," Parilla recently told Entertainment Weekly. "It's really her journey of exploring that. It's an immense amount of responsibility. We'll see her evolving into this role and we'll see where she ends up." 

Yet it seems that Regina is not that enthusiastic to fill the hero's shoes. According to Parilla, Regina has no choice since Emma willingly sacrificed herself to fulfill her promise to Regina that she would give her a happy ending. She decides to pay back the good deed because she hates owing someone. 

Parilla said that Regina's inner darkness – combined with Hook's (Colin O'Donoghue) – will be useful in helping lure Emma to returning to her old self. Series executive producer Adam Horowitz also explained that the two people who experienced harboring darkness themselves will be instrumental in her new journey.

"The fact that she's facing darkness, and they've faced it, and how their experiences can inform what she's going through and either help or hinder her, is something that we want to explore in this half of the season and beyond," Horowitz shared. 

The official synopsis for the premiere episode called "The Dark Swan" reads: 

Immediately after becoming the Dark One, Emma disappears and the heroes must band together to save her, but first they have to find her, which will require the help of an unlikely ally. Meanwhile, in the Enchanted Forest, Emma struggles to resist her dark urges as she searches for Merlin in the hope that he can stop her transformation. Along the way to Camelot, she gets help from the plucky and brave warrior princess Merida, as well as King Arthur and his Knights of the Round Table."

"Once Upon a Time" season 5 premieres on Sunday, Sept. 27, at 8 p.m. EST on ABC.