'Arrow' finally reveals Prometheus' identity, but when will Oliver find out?

Arrow finally revealed the identity of its Season 5 big bad, Prometheus — and it probably wasn't who you thought it would be, considering the character's comic book alter-ego is something entirely different.

But it turns out that the person emotionally torturing and manipulating Oliver this whole time has been Adrian Chase (Josh Segarra), the Star City District Attorney. Yes, in the comics Chase is actually Vigilante, but executive producer Wendy Mericle told Mashable and a small group of reporters that the plan to turn him into Prometheus on the show has been in the works for a year. 

"We knew that’s what we wanted him to be, that’s how we wanted to build it," she said. 

With Arrow in its fifth season, the writers decided to introduce a Big Bad in an entirely different way. "We thought it would be a really fun twist to do what we've always done on the show which is to take the comic book mythology and turn it on its head and see what kind of story we can mine from a surprise like that," she said. "It was also something different for this season. We wanted to change up how we introduced the big bad and change up when we did it, and hopefully we succeeded in that this year."

While the audience now knows the identity of Prometheus, Oliver and company don't — and it'll be a little while before they find out. "They're going to find out who he is. We're not going to leave it to the end of the season," Segarra told Mashable — but it won't happen immediately. "We're going to get to watch the pot get stirred a little bit. It's hard because I already know how he reacts, and I love the way it goes. You're going to see Chase just kind of trying to burn the world around him."

Original image has been replaced. Credit: Mashable

The fact that Oliver and Chase have bonded throughout the course of Season 5 will make the reveal especially painful for our hero. "Ultimately, the bond between them is really strong, which we hope will... create a much bigger impact on Oliver when he finds out down the road who Adrian really is and that this is the guy who's been really messing with him all season," Mericle said.

But why does Chase have it in for Oliver? "On the show, historically we've always striven to have the villain be the hero of their own story and to really kind of get underneath the reasons why they are what they are and do what they do. Adrian Chase is no exception," Mericle explained. "We will get a lot more sense going forward, I think, of why he has become so evil, why he's so bent on revenge."

Taking Susan? That's part of the revenge plot, according to the producer. "His goal is very clear. He really has no drive to kill Oliver," Mericle said. "It’s purely based on torture and so, in taking Susan... it’s all part and parcel of this drive to break Oliver down psychologically as opposed to physically, which we have seen Slade and Merlyn and everybody else do — take him on hand-to-hand. This is much more of a mental game."

Said Segarra, "It's the chess match ... He's moving pieces that he knows Oliver's not going to be able to catch up with and I think that Susan is a very, very important piece of that puzzle and Chase knows that."

Ultimately, Chase and Oliver have similar stories, Mericle pointed out: "I think what's so interesting for us is how close those parallels are with Oliver's own story. We really did want to this season build a villain that's a dark mirror for Oliver, in the tradition of the comic books and honoring that, and honoring Oliver's past on the show, especially the first season, seeing what it was like going through the loss. They've both suffered losses and they've both answered those losses in very different ways."

Arrow airs Wednesdays at 8 p.m. on The CW.