Once Upon a Time is going to its darkest place ever: the underworld. In the midseason finale, Emma (Jennifer Morrison) rounded up her family and friends to rescue Hook (Colin O'Donoghue) after Rumplestiltskin (Robert Carlyle) betrayed them all — and in turn forced her to kill her love — but it won’t be an easy journey.

 

The spring premiere on March 6 also marks the show’s 100th episode, which means visits from lots of familiar faces. After kicking off with such a nostalgic-themed episode, the second half of the season will also include a bewitching return from Zelena (Rebecca Mader), a possible baby for Belle (Emilie de Ravin), and the drama’s first gay storyline.

 

Below, THR rounds up all of the intel about what’s to come in the spring.

 

What Is the Underworld Like?

 

In the first glimpse at the underworld, it looked a lot like Storybrooke, and co-creator Adam Horowitz told THR that there’s a “very specific reason” why it looks like the familiar town, and it has to do with the characters Emma & Co. will interact with.

 

The Underworld is also not hell, but instead a place for people with unfinished business. “The second half is a lot about them getting closure on their pasts and how the past comes to haunt you,” co-creator Eddy Kitsis added. 

 

 

Who Is Returning?

 

A lot of old characters are returning for the 100th episode Prince Henry (Tony Perez), Cora, (Barbara Hershey), Sidney Glass (Giancarlo Esposito), The Blind Witch (Emma Caulfield) and Peter Pan (Robbie Kay) will be back, while Cruella de Vil (Victoria Smurfit) and Milah (Rachel Shelley) will appear later in the season. 

 

The OUAT bosses also tell THR that Mulan (Jamie Chung), Ruby (Meghan Ory), Arthur, Merida, and Guinevere will be back in some capacity, and Zelena will be part of a major arc after returning midway through the second half. Hook’s brother, Liam, will also appear.

 

Unfortunately, Jamie Dornan will not return for the big 100, though. The Fifty Shades of Grey star’s schedule is too busy, but Kitsis told Variety that Graham will “be there in spirit as Emma wears his shoelaces on her wrist.”

 

Who Will Die?

 

With so many villains waiting in the underworld, it seems easy for everyone to get killed off immediately, but that may not happen. “The rules of the underworld — what it means to be there, whether you can leave, how you can leave, where you go — will be explained by Cora,” Horowitz and Kitsis said. 

 

 

And now that Rumple has absorbed all the former Dark Ones’ powers, expect him to have new strengths to fight others off. “He definitely has all of the powers of those Dark Ones and he’s emerged stronger and probably even a little wiser,” Kitsis teased.

 

Who are the New Characters?

 

Hercules (Jonathan Whitesell) and Meg (Hannibal’s Kacey Rohl) will appear in Episode 13, “Labor of Love,” and Young Snow White (Bailee Madison) will be somehow involved. 

 

Hades could also be coming as Ally McBeal‘s Greg Germann recurs as “The Distinguished Gentleman” — especially since he’s described as a “mysterious figure with God-like powers.”

 

What are Everyone’s Relationship Statuses?

 

When THR asked the co-creators if star Emilie de Ravin’s pregnancy would be written in with Belle, Kitsis played coy. “I would say it certainly looked like they re-consummated their marriage, so we’ll just have to wait and see, but I would say you’re definitely on the right clue trail,” he revealed.

 

Meanwhile, Emma will do everything in her power to save Hook. “She finally lowered that wall and let Hook in, so she doesn’t want to lose another person who she loves,” Kitsis explained. “So echoing her father’s line, ‘I will always find you,’ and I think come hell or high water, she’s gonna try.”

 

One of the most important storylines of the second half will be the show’s first gay storyline — but it won’t be a “very special episode of Once Upon a Time,” Horowitz told THR. “What we're endeavoring to do is to not make a big deal of it because that's how we see this world — it's not a big deal. It should just be a love story that is as exciting, emotional and heartfelt as any other love story.”

 

Once Upon a Time returns Sunday, March 6 at 8 p.m. on ABC.