The world of ABC's Once Upon a Time is expanding even more in the upcoming fourth season of the fantasy series as fans are introduced to the mother of one of the main characters.

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Season 4 will feature the introduction of Belle's (Emilie de Ravin) mother, according to a new report by Entertainment Weekly. Once Upon a Time co-creator Adam Horowitz revealed the news to the publication, saying that they will be flashing back to Belle's early life for the first time.

"We are going to meet Belle's mother. For the first time, we'll delve into Belle's past pre-the encounter with Rumple [Robert Carlyle]," he said.

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As the publication notes, this means that in addition to learning about Belle and her history, fans will also finally see who Sir Maurice (Eric Keenleyside), a.k.a. Belle's father, is married to.

Casting for Belle's mother has not yet been revealed.

In the present day, Belle will be busy with her new marriage to Rumple, though the honeymoon phase doesn't seem to last very long. According to Carlyle's previous comments, Season 4 will feature Belle and Rumple being happy "maybe in the first episode, but then that's it."

He also teased that the big Twitter hashtag for the episode will be "#Dance," though he did not elaborate on why this will be the case.

Once Upon a Time Season 4 is set to premiere Sunday, Sept. 28 at 8 p.m. on ABC.

Tags: Once Upon A Time television ABC