None of the heroes of Once Upon a Time have a past history with Hades (Greg Germann) but last Sunday's episode revealed that the Lord of the Underworld has another wicked connection.

The secret to defeating Hades is with Zelena (Rebecca Mader). The missing storybook pages reveal that Hades and the Wicked Witch have a big secret together and so now the heroes must track down their least favorite person if they want a chance of saving Hook (Colin O'Donoghue) and returning home. In the meantime, Hades is aiming a precise chisel at each of the heroes' Achilles' heels, including the formidable Rumpelstiltskin (Robert Carlyle).

Greg Germann talked to TVGuide.com about what Hades' past with Zelena will reveal and why he takes such pleasure in being so bad. See his answers below.

Once Upon a Time: Can Hades trap the heroes in the underworld forever?

What can you tease about the nature of his relationship with Zelena?

Greg Germann: Hades and Zelena could either be great adversaries or a great match. Because of both of those things, they are both formidable in their own way. There's definitely some sparks that will fly in one direction or another between those two.

What does he plan to do with Rumpelstiltskin and the unborn child?

Germann: Anything that is going on with Hades, whether its with Rumple or any of the other characters, he's an opportunist. It's not so much that he wants a baby but he's finding the Achilles' heels of all the characters to move things forward for the things that he wants.

Hades makes it clear that he can kill any of the heroes at any point, but he seems to take more pleasure in torturing them. Why is that?

Germann: It's really fun to have one up on your adversary. What if the world were that way — if we had some adversary in the world and we could just go 'Yeah you're gonna do that? Well what about this?' and stump them. That would feel really satisfying. In a way, Adam [Horowitz] and Eddy [Kitsis] are writing to that desire that we all have in us if we could all just easily one up the people that are hurting us. Hades, like Zelena, has abandonment issues, which is a funny way to say it. They both in their own way have suffered in their lives. They feel that they are the other end of some victimization maybe. I don't want to say there's any bitterness there, but if they can get back at the world that feels satisfying. It feels good.

Does Hades have any particular feelings on Zelena and her new baby?

Germann: I don't know that he's got strong feelings that she's had other relationships. Hades is very mature. I don't know if that's the issue necessarily for him or other things like whether the sparks that fly between them or the power that each of them have can enhance each other and help one another.

Will we find out why Hades chose Regina, Emma and Snow White as the three of the heroes that he wanted to keep?

Germann: That's something you have to wait to tune in to see. Hades isn't really doing anything arbitrarily. Everything that Hades is doing, there's a reason why [he's] doing it. I definitely have an agenda and everything I'm doing is moving that agenda forward.

Is his ultimate goal to keep everyone down there or would he be willing to let some of them go?

Germann: I like having people down there. I don't want to let anyone go. The more lost souls, the more souls down there that have unfinished business, as Adam and Eddy say, the better. Hades' ultimate ambition is an ABC spinoff.

One of the things this show loves to do is show a human side to its villains. Will we get to see that side of Hades?

Germann: Yes. What Adam and Eddy understand as writers is that these characters, whether they're humans or villains, they're three dimensional. It's not just a two dimensional renderding of a bad guy or a good guy. We've got all sides to us, even Hades ultimately.

Once Upon a Time continues Sunday at 8/7 on ABC.