The 15th episode of ABC's Once Upon a Time, season 4, is slated to feature Ursula's (Merrin Dungey) backstory, with appearances by Ariel (JoAnna Garcia Swisher) and her father.

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Ursula was introduced as one of the Queens of Darkness in the winter finale of Once Upon a Time and she will get her own flashback, as most of the show's characters do.

It was recently announced via Entertainment Weekly that actor Ernie Hudson would be playing Poseidon, the Greek God of the Sea who also happens to be Ursula's father. Hudson will be appearing as Poseidon in the show's 15th episode of the current season.

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As mentioned, Garcia Swisher is set to return as Ariel in this episode as well, suggesting that the two characters are necessary to tell Ursula's backstory.

Once Upon a Time co-creators Edward Kitsis and Adam Horowitz recently spoke about Ursula and how they intend to explore the sea witch's mythology going forward.

"What we're planning to do is explore this Ursula mythology in our show and explore a backstory of who she is and what Ursula is all about," Howoritz explained.

Kitsis added, "We've always said evil is not born, it's made. One of the things we're so excited about with these three villains is showing their origin stories. We've never see the origin stories with Maleficent [Kristin Bauer van Straten], Ursula or Cruella [Victoria Smurfit], so we're excited about that."

Once Upon a Time returns for the latter 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, titled Darkness on the Edge of Town, here:

Tags: Once Upon A Time television ABC