'The Flash' showrunner on how Season 8 was conceived as series finale, teases what's next in Season 9

The Flash will keep running for a ninth season on The CW, continuing its run as the network's longest-tenured current superhero series. We've known that for several months now, but with several other superhero shows ending their time on the network in recent years, the future feels murkier than ever for the fastest man alive. Thankfully, showrunner Eric Wallace has a plan, and it's a plan that feels just a little bit clearer in the wake of this week's Season 8 finale. 

**Spoilers for The Flash Season 8 ahead.**

As is usually the case for The Flash, this season wrapped up with an epic showdown between Barry Allen (Grant Gustin), and a formidable foe, in this case Eobard Thawne's (Tom Cavanaugh) latest transformation into the Negative Reverse-Flash. But even by Flash standards, this battle felt like an especially massive one, with the literal end of the world on the line if things happened to go wrong. Barry ultimately won the fight by, ironically, choosing not to fight at all and letting Thawne burn himself out on his own power, but it still stands as one of the biggest confrontations in the show's history. That's because, according to Wallace, it was originally written to work as a series finale for The Flash. 

"[W]hen we were writing the finale for Season 8, we thought that was the series finale," Wallace told TVLine when asked if he had any idea how he'd craft a showdown for the end of the series that will top Season 8's wrap-up. "So we were like, 'We’ve got to have the greatest, most epic battle ever between Grant [Gustin] and Tom! That’s how it has to end.' And after the script was done and we were getting ready to start prep, that’s when we got the news that we would be getting a ninth season. So we were like, 'Oh crap, we just did the ultimate battle. How are we supposed to ever top that?' Then it was like, 'Let’s just kill him for now and worry about that later.' [Laughs] Because Reverse-Flash and the Negative Reverse-Flash, just like Frost, are dead. I mean, they are dead. Now… having said that… it is a comic book show, and I’m pretty sure that in Season 9, there’s some reason that you might see Tom Cavanagh again. I won’t go into it, but that’s a pretty safe bet."

But the finale wasn't all about major departures. There was a key re-arrival too, in the form of Iris West-Allen (Candice Patton) finally returning to Barry after preserving her consciousness in the time stone her father managed to hold on to as a gift from Damien Darhk. Iris was able to come back thanks to her ability to remember and re-establish the connection with her husband, and according to Wallace, that means that after a few seasons with a lot of separation, we'll finally get to see more of Barry and Iris living as a couple again in Season 9. 

"Yes, I can unequivocally say that in Season 9 you will see much, much more of Barry and Iris together," Wallace said. "Not just together in the same room, but together in all ways. It’s something that is a part of the new approach for the new season. Every season is different, and Season 9 is going to be very, very fun and very exciting.

"The reason we can do that is because of what [WestAllen] have been through over the last season-and-a-half specifically, being apart and growing individually. As we see in this finale, Iris was the last person to have not “leveled up” yet, and we get to see it actually happen in the episode. Now that she has completed her journey of leveling up, she and Barry can both face what is coming in Season 9 together, as a couple. So you will see much more of them together, unlike what you saw in Season 8 at times."

As for what actually is coming in Season 9 for Barry, Iris, and the rest of Team Flash to fight, Wallace was of course a bit tight-lipped at this point, but the show did leave us with a coda sequence to serve as a teaser. Before signing off for the season, we got a look at a lab in the year 2049, and a glowing blue crystal that seems to point the way to a new villain. So, who is it? If you want clues, study your Flash comics — though we'll note that crystal certainly seemed cobalt.

"The hardcore comic book fans know what’s coming; those who don’t, I’m not spoiling it here, so it’s going to be a big surprise for them," Wallace said. "But yes, we’re pulling directly from the comic books here, and boy is it going to be fun."

The Flash will return next year with its ninth season. 

Looking for more sci-fi adventure in the meantime? Check out Battlestar Galactica, Heroes, Warehouse 13, Eureka, SYFY's Resident Alien, Sliders, Intergalactic and more on Peacock now.