Once Upon a Time's Zelena may be the key to defeating Hades

Mar 27, 2016 at 9:57 p.m. ET
Image: ABC

Little by little, each new Once Upon a Time episode reveals more and more about Hades. During Sunday’s episode, not only did fans learn that Hook's brother once made a deal with Hades back in the day, but we also learned that there is an "Underworld Edition" of the "Once Upon a Time" storybook offering up details about the dangerous man downstairs.

More:Once Upon a Time's Rumple deserves Hades' wrath

At the end of the episode, viewers got a glimpse of the pages (after Liam tore them from the book and hid them from Emma, his brother and everyone else). Guess what? Hades and Zelena have a connection. That's right. Regina's sister apparently had a romance with Hades — or that's what the promo for next Sunday's episode teased.

Anyway, while staring at the storybook page of himself and Zelena, Hades said, "our secret remains safe." What exactly is their secret? That remains to be seen and safe (for now), but Zelena may very well be the key to defeating Hades.

If she and Hades were romantically involved, then Zelena just might know things about him that no one else does. People become vulnerable when in love, so if Hades loved her, he may have opened up to her. Zelena was banished back to Oz in the Season 5 midseason finale, and Emma, Regina and everyone else needs to locate or get in contact with Zelena stat.

More: Once Upon a Time's Henry may soon become a target in the Underworld

Zelena, OUAT
Image: Tumblr

Even though it may seem like Zelena and Hades knowing one another is a bad thing, it might turn out to be a very good thing. Whatever she knows about him could come in handy.

Plus, maybe Zelena will side with Emma and everyone else to defeat Hades. Maybe Zelena can even trick him somehow and she'll end up saving the day, becoming the hero of the story. This is a great way for Zelena to earn trust, especially from Regina and Robin Hood — aka her baby's father.

With that, I'm ready to learn all about Zelena and Hades' mysteriously wicked past in next week's episode.

Once Upon a Time airs Sundays at 8/7c on ABC.

More: Once Upon a Time's Robin Hood might not make it out of the Underworld

Before you go, check out our slideshow below.

OUAT Dark One slideshow
Image: Graphics provided by SheKnows; photos provided by ABC