Arrow finally revealed who the person behind the mask of its Season 5 Big Bad is, and the real identity of Prometheus might have been a surprise for many people. To weigh in on what the reveal means for the show and its main characters going forward, we spoke with showrunner Wendy Mericle and the actor who we didn't realize was playing Prometheus the whole time.

Prometheus on Arrow

Full spoilers for Arrow continue below, so read on at your own risk. Make sure to read our review of "Fighting Fire with Fire."

Stephen Amell as Oliver Queen andJosh Segarra as Adrian Chase on Arrow

Prometheus on Arrow

And Prometheus is... Adrian Chase. You thought he would really be Vigilante? You thought wrong. It doesn't seem as though he is Vigilante as well , according to showrunner Wendy Mericle, and that's why they wanted him specifically as Prometheus."One of the reasons we did do it was because everybody would be thinking, 'Of course he's going to be Vigilante," she told reporters in a recent interview. "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. 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, how we did it, and hopefully we succeeded in that this year."Josh Segarra also fell into the trap of thinking he'd be playing Vigilante. Though the executive producers on the show described his character as the Big Bad of the season, once he found out he'd be playing Adrian Chase, he initially figured he'd be playing Chase's comic book alter ego. Segarra found out the hard way when he got to set to start filming that he'd actually be playing the season's villain."They announced Adrian Chase, Vigilante. And I'm like 'oh my gosh! I'm playing Vigilante!' So now, I get to Vancouver and I think I'm playing this guy Vigilante because that's who everybody thought, right? I started reading Vigilante comics, and I'm reading about Chase, and reading all about the history of these guys, and I get to work and I'm talking to Marc and I'm like 'Marc! I'm really doing my research! I'm really being studious about the Vigilante guy' and he's like 'What do you mean?'" Segarra recalled. "I'm like, 'Oh, dude, you know. We announced it, finally! So I'm going to be a great Adrian Chase - Vigilante.' He was like, 'That's not who you're playing.'"Though the audience now knows Chase is Prometheus, Oliver and Team Arrow are still in the dark. Mericle explained that the Prometheus reveal came relatively late in the season because they wanted to build up Chase's relationship with Oliver before pulling the rug out from under the audience. Arrow will explain Chase's motivations and backstory in the coming episodes, leading up to the inevitable reveal of his identity to the rest of the characters on the show."We're not going to leave it to the end of the season," said Segarra. "We're going to get to watch it all stir, and 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. We've seen the reluctance [in] him to kill [Oliver]. I never want to kill him. It's just to make sure that we can make him stir a little bit, make him uncomfortable. So I think that's where it's going. Once they do find out, it's how then to continue with my mission.""I think one of the fun parts about what we’ve done is to really allow us to live with that reveal for a while and seeing the characters not knowing what their lives are like, still continuing to interact with Adrian Chase in City Hall and elsewhere without knowing his real identity," noted Mericle. "We really like the idea of doing that in story, and we’re going to play around with that for a little while before we let Oliver and the team find out."His supposed kidnapping of Oliver's ex Susan Williams is yet another development in his plan to torture and torment the mayor of Star City. Though Segarra and Mericle wouldn't say how long Susan would be in Prometheus's custody, they did tease how this latest development in Chase's "mental game" will play out."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," said Segarra. "Susan is a very, very important piece and a very good move in the big chess game that's going on. And then to get to see that relationship, how it develops between the two, because ... Susan may feel betrayed by Oliver, so it's interesting to see how Chase will try to let's say navigate those waters, how he can get to his next move."

Terri Schwartz is Entertainment Editor at IGN. Talk to her on Twitter at @Terri_Schwartz