SPOILER WARNING: This article contains major spoilers for "Fighting Fire with Fire," the latest episode of "Arrow."


Prometheus has been unmasked. In "Fighting Fire With Fire," the latest episode of "Arrow," the Season 5 big bad removed his mask and revealed District Attorney Adrian Chase underneath. That's right: Chase has been the one plaguing Oliver as Prometheus all season.

Chase revealed himself after a battle with Vigilante. He tracked Vigilante down to a rooftop as Prometheus, and the two quickly came to blows. The battle ended as swiftly as it started when Prometheus threw Vigilante off of the rooftop. We never see a body, so at the time Vigilante's fate is unclear, though he does resurface by the end of the episode. Nevertheless, Prometheus removes his mask and calls in a Vigilante sighting as Adrian Chase -- which wouldn't be terribly suspicious, considering Vigilante just attacked the mayor and his entourage.

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At the very end of the episode, Chase pulled another surprise move and approached Susan at her car late at night. As he spoke to her, Prometheus' theme played over his words, suggesting his ill-intent. As seen in the preview for next week's episode, Chase has kidnapped her -- and he reveals his identity to Oliver, who must race against the clock to save her.

Asked why the showrunners chose to make Adrian Chase into Prometheus rather than Vigilante, executive producer Wendy Mericle said, "I think one of the reasons we did that was because everyone would be thinking, 'Of course he's Vigilante!' Adrian Chase is Vigilante in the comic books, and we thought it would be a really fun sort of 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 could mine from a surprise like that. It was also just something different for this season. We wanted to change up how we introduced the big bad and change up when we did it and how we did it. Hopefully, we succeeded in that this year."

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"We always knew that Adrian Chase -- and Josh Segarra playing him -- was our big bad," she added. "We always knew -- from the beginning and our very first discussions, which began about a year ago -- that's what we wanted him to be and that's how we wanted to build it. I think, in terms of the timing of this specific episode, we had to play around with that a little bit more. There are certain moments in the season where you obviously want to build to. We could have done it in [season] 5 [episode] 9, we could have done it a little later in [season] 5 [episode] 18, but I think as much as possible we try to let the stories dictate where these big reveals happen, and it just felt right here and it felt right also to do it in the middle of an episode. That, also, I think played against expectations in a good way."

Prometheus himself Josh Segarra also addressed that episode-ending cliffhanger, where Chase kidnaps Oliver's ex-girlfriend Susan Williams. "I think that there is a means to an end for each move that he makes, and that's not part of the Prometheus, that's part Chase for me. When I look at Prometheus, I look at the skill set that he's out in the streets, and that's taking part of one aspect of this. The part that Chase is doing is the mental game," he explained. "It's the chess match, and that's what Chase has been playing the whole time. He's moving pieces, and he knows Oliver's not going to be able to keep up. I think that Susan is a very, very important piece of that puzzle, and Chase knows that. I think that there are other very important pieces of the puzzle -- other pieces on that chessboard that he's going to move -- and Susan is a very, very important piece and a very good move in the big chess game that's going on. And then you get to see that relationship and how it develops between the two, because you're right: 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."

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As to Oliver's reaction when he finds out Chase was Prometheus all along, Segarra teased, "We're not going to leave that until the end of the season. 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. I think we've seen the reluctance of him to kill him. I never want to kill him! It's just to make sure 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 know how that goes, but you'll have to see."

"In the look back, when Oliver and the team do find out, which will happen later in the season -- obviously it will happen sometime after this episode and before the finale -- but 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," shared Mericle. "We really liked the idea in the story, and we're going to play with that for a little while before we let Oliver and the team find out."

Airing Wednesdays at 8 p.m. ET/PT on The CW, “Arrow” stars Stephen Amell, Emily Bett Rickards, David Ramsey, Willa Holland, Paul Blackthorne and Echo Kellum.