Once Upon a Time co-creators Edward Kitsis and Adam Horowitz recently discussed the theme of the upcoming second half of season 4 and what Rumplestiltskin (Robert Carlyle) has been up to.

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Kitsis and Horowitz recently spoke with Entertainment Tonight about the upcoming Queens of Darkness storyline, which introduces Cruella de Vil (Victoria Smurfit) and Ursula (Merrin Dungey) and re-introduces Maleficent (Kristin Bauer van Straten).

Ultimately, the theme of the season will be about characters simply trying to find their happy endings, whether they be heroes or villains.

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"This back half is a lot about what makes a hero and what makes a villain, and it's about trying to realize our happy endings," Kitsis proclaimed.

The co-creators said that it was a "safe assumption" that Rumplestiltskin has been busy tracking down the three villains in the midseason break.

As one would expect, the villains will definitely have an intricate part in many core characters' respective pasts.

"Those characters who have been there through the years will have their past, and their present, and their futures intertwined with the Queens of Darkness," Horowitz said.

Such core characters include Regina (Lana Parrilla), Snow (Ginnifer Goodwin), Charming (Josh Dallas) and more. As such, there will be greater focus on these core character in the latter half of the season, compared to the first half, which was very focused on Frozen and the Snow Queen (Elizabeth Mitchell).

"I think that this second half is really going to focus on our core people again, and we're going to get to see a lot of the people that we've loved since season one," Kitsis said.

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

Watch the promo for the next episode of Once Upon a Time here: