Maleficent's (Kristin Bauer van Straten) dark past will be revealed in the second half of the fourth season on ABC's Once Upon a Time.

'Once Upon a Time' Star Lana Parrilla Talks How Maleficent Is Most 'Formidable Foe' Amid Trio Of Villainesses

Once Upon a Time co-creators Edward Kitsis and Adam Horowitz recently spoke with The Hollywood Reporter about what to expect from the Queens of Darkness and how Maleficent is the most dangerous of them all.

"I would say she is probably the most dangerous. But what Regina [Lana Parrilla] did to her is secondary to what someone else did to her," Kitsis said. "And that we're going to explain pretty quickly. And it will be, probably, someone you didn't expect."

'Once Upon a Time's Maleficent, Cruella & Ursula Have Surprising 'Connection' With Two Characters

Fans will recall that Regina locked Maleficent away underground in dragon form for a full 28 years.

Will Once Upon a Time go down the path of the Angelina Jolie movie Maleficent and have someone clip her wings in the middle of the night? It is possible, given the popularity of the film this summer.

"We're going to see how the Evil Queen met Maleficent. When we met them in season one and they were what we affectionately called 'frenemies,' we're going to see how that relationship started," Horowitz said.

As for their reunion in the present day, Horowitz teased that it won't exactly be a welcome one.

"After locking someone underground as a dragon for 28 years, that'll test the bonds of any frenemies," he noted.

Once Upon a Time returns for the second half of season 4 on Sunday, March 1 at 8 p.m. ET/PT on ABC.

Watch the trailer for the next episode of Once Upon a Time below: