Warning: This article contains spoilers for the season 7 finale of The Flash.
Original cast member Tom Cavanagh — who exited the CW superhero drama midway through season 7 — returned in Tuesday’s finale as the character everyone loves to hate: Eobard Thawne, a.k.a. Reverse Flash. In the face of the enormous threat Godspeed posed to Central City and the world, Barry (Grant Gustin) realized the only way to defeat him was to team up with the man who killed his mother. So the Speed Force reconstituted Thawne’s body, and the evil speedster joined Barry in a lightning-sword fight against Godspeed. The clash ended when Thawne stabbed the golden speedster.
Of course, villains are gonna villain, and Thawne immediately turned on Barry. But he ended up speeding into the night when he realized Barry was finally faster than him. Thus, Barry and Iris (Candice Patton) were able to renew their vows in peace.
Candice Patton as Iris West-Allen and Grant Gustin as Barry Allen on ‘The Flash’
| Credit: Bettina Strauss/The CW
ENTERTAINMENT WEEKLY: Where did the idea to bring Reverse Flash back in this way come from?
ERIC WALLACE: I’ve had that idea for a year. It’s just been in my pocket and I haven’t been able to say a word, and I’ve been dying to tell everybody. [Laughs] Like, “Just be patient. He’s always going to be back.” Because it was very important when we were establishing a new villain speedster in Godspeed to show how really dangerous Godspeed is. He’s so dangerous that the Flash has to partner with his worst enemy to defeat this guy. I told Karan, he flipped. I told Tom way early. Tom’s been hiding this for nine months, it’s really hilarious. Good for him for keeping the secret.
And what about the lightning-sword fight?
I was reading The Flash comic [series] that Joshua Williamson is writing, which I love, and there was an image in one of the comic books of Godspeed holding up a lightning sword. I thought to myself, “What if it wasn’t one sword but three swords, three speedsters, and they’re all super-fast? That would be amazing if we could pull that off.” I think it was a year and a half ago, before I even started to think about season 7.
Then when we started to put season 7 together and I realized we would need Thawne’s help to take down Godspeed, it literally was like synchronicity. You could hear the heavens open up. “That’s it! That’s our lightning-sword battle!” Then I had to convince my director, my cast, and crew that I was not insane and I could actually do this, and that we could all pull it off for television. I won’t lie, it did push every department to the max, but everybody rose up: stunts, Jon Kralt did an amazing job with the choreography; Kate [Main], our costume designer, had to come up with all those extra costumes; the actors had to learn the stuff the stunt performers were doing so they could mimic it. Poor Marcus [Stokes], our director, who is just amazing and has been with us for many years. He and I were joking at one point, “Wow, we’re really doing this, aren’t we? We’ve past the point of no return. All right, double down!” Then we decided to make it bigger. Hopefully the end result is something that will be a very memorable sequence for years to come for Flash fans.
In the past you’ve said you had a multiseason plan when you took over as showrunner. Was Bart’s [Jordan Fisher] introduction always part of that? What made this the right time to bring that character in?
Yes, Bart has always been the plan. Although ironically, we were originally going to introduce Bart in season 8, not season 7. Then COVID happened and we had a whole bunch of time to think about how to reshape the season. I realized, “Let’s pull that up. That might be a good thing to do in the 150th episode as opposed to waiting for season 8,” because to be honest with you, when we started to write all this stuff a year ago I wasn’t sure what was going to happen. Would there be a season 8 at that point? So I also couldn’t take the chance. I wanted to make sure at least Impulse got an appearance. Fortunately, we did get an eighth season.
John Wesley Shipp as Jay Garrick, Jordan Fisher as Bart/Impulse, Candice Patton as Iris, Grant Gustin as Barry/The Flash, Jessica Parker Kennedy as Nora/XS, and Michelle Harrison as Nora in the season 7 finale of ‘The Flash’
| Credit: Bettina Strauss/The CW
What made Jordan the right person for that role?
It’s a funny story. I worked with Jordan about four or five years ago on Teen Wolf for a couple of episodes; he was a guest star for us. We were shooting werewolves, and it was 5 in the morning, and we’d been shooting all night. The sun’s rising. Poor Jordan — it’s in season 5 and he’s got that gold werewolf blood in his mouth, and he’s just smiling. And he’s giving this great performance and his energy is so positive. And I thought to myself right there, “This guy is just amazing. I have to work with this person again. I don’t know when, I don’t know how.” But I keep a list of people who are all awesome people I want to work with [again], so I put him right on that list.
Cut to four years later, I’m thinking about Impulse and I immediately said, “It can only be Jordan. He is my only choice. He is my No. 1 — but there’s no way we’ll get him because he’s famous now.” So we kind of just moved away from him and auditioned a lot of wonderful people who were really amazing. Then, I think somebody — it might’ve been Greg [Berlanti] or Sarah [Schechter] — at Berlanti [Productions] just went, “You know, we really should just check with Jordan just in case.” We did, and to my pleasant surprise he was into it. Next thing you know, Jordan was Impulse and it was a dream come true for me. That’s when I knew we’d made the right decision, because it felt like synchronicity. It felt like something special was happening. Hopefully that came through in his two episodes. When he and Jessica Parker Kennedy are in some of their scenes together, it feels like they’ve been brother and sister for years.
Do you have plans to bring Bart and Nora back next year?
If I was a betting man, I would say you will definitely see Jordan and Jessica again next year. It’s just a matter of when and how they return. Because they’re just so fantastic, we just can’t wait to have them back on the show.
Was Iris gaining speed powers a one-time, or more accurately a two-time thing, or will she keep them going forward?
No, Iris is not a speedster. This is a one-time thing. However, in the season  premiere, Iris has a whole new thing going on that’s really exciting! She has so many exciting things to deal with next year in the non-speedster capacity, which is the journalist side of her, that we are so excited about. I won’t go any further.
Are you approaching season 8 as if it might be the last one?
You know, I get asked this question all the time and it’s weird because I honestly don’t know whether it is or not. So I’m just treating it as “Let’s tell the best season we can.” It’s something I tell the writers all the time: “Tell every story every week as if this is the last Flash episode we all get the privilege of telling.” That’s how we sort out our ideas by priority. Because we have such a talented group of writers, we have so many ideas that we can’t get them all in a season, but that’s great because that allows us to prioritize. But all I can tell you, and this is total honesty, we will continue to do what we always do, which is approach every episode as “How can we make this episode and this season the best one ever?”
Jessica Parker Kennedy, Candice Patton, and Grant Gustin on ‘The Flash’
| Credit: Bettina Strauss/The CW
There’s so many guest stars that we want to bring over, and those will all be announced later, so I don’t want to drop any spoilers. But I will say the whole gambit is open — it’s wide open. We are considering literally every character from every Arrowverse show to potentially come and play with us for part of this five-part special event. So who knows? Ask me that question in three months.
Are you approaching this as a five-part story, or is it five standalone episodes?
It’s a five-part event. We’re going to do what we always do, which is our graphic novel format. We’ll be telling a self-contained story, no spoilers there. But we’re just going to up the ante. The idea behind this is to give the audience a big gift of “Thank you for hanging with us through everything that we’ve been through together in the last couple of years, and what we’ve all been together as fellow Flash fans and part of the Flash family for seven years.” So this special event is designed to feel like a crossover but not be a crossover. Obviously we don’t have the time and resources and all of that stuff. But we want to give you guys the same feeling you would get in bigger emotions, a bigger Barry-and-Iris story that has great risks to it, and as many guest stars as time and resources will allow.
The Flash will return Tuesday, Nov. 16, at 8 p.m. ET/PT on the CW.
We Are The Flash
After the success of Arrow, Barry Allen (a.k.a. The Flash) gets his own CW treatment in this comic-themed spin-off.