In the premiere of the final season of The CW series The 100, Clarke (Eliza Taylor) and her friends attempt to rebuild Sanctum, but despite their determination to do better, a new threat rises in the woods. On the constant edge of battle and with the lives and future of humanity in the balance, the seemingly never-ending fight could be what finally ends them all.

During this 1-on-1 phone interview with Collider, showrunner Jason Rothenberg spoke about the tight schedule they had to finish the series finale as production was getting shut down due to COVID-19, making the decision that Season 7 would also be their last, how close the final season and final episode are to what he thought they might be, and the challenges specific to doing an episode that also serves as a backdoor pilot for a possible prequel.

Collider: You finished filming this series finale down to the wire of production getting shut down. What was that like? What were the challenges of trying to get this finished, under those circumstances? You finished shooting the season, but how hard was it to have to quickly shut everything down like that?

JASON ROTHENBERG: It was really hard, but the hardest thing was not being able to really just hug everybody when we wrapped. By the way, I semi-lied because we hugged everybody anyway, and fortunately nobody got sick. You’re right, we were up against it. We had three days left to shoot when they called to say that everybody was shutting down. They also said that we could finish, but we had to come up with a plan to do it quickly, so we pulled up scenes from the third day, and did three days of shooting in two days. We pulled the Monday work up to Saturday, and we shot on Saturday. There was supposed to be this huge 100-episode celebration party that night at a restaurant bar, and everybody was gonna fly up from L.A. and it was supposed to be a big deal, but it was canceled. Instead, and probably for the best, it was just a cast and crew celebration on our Sanctum tavern set, which was emotional, but also semi anti-climactic.

When you announced that Season 7 would be the last season of the show, you called it bittersweet news. How was it decided that this would be the final season? Had you been hoping to continue it on even further, or was this just where it needed to end?

ROTHENBERG: This was where it needed to add. I don’t know if the studio and network would have let us continue into Season 8. I assume they would have. They were gracious enough to let us do 16 episodes, to get to episode 100 this year, so I assume they probably would have wanted more, but we were ready. It’s a long time to be telling the story of one group of characters. One of the things that kept it so fresh for us, every year, was that we did change it a lot and we introduced new people a lot. We also didn’t want to overstay our welcome and be a show that was making episodes into Season 10 and 12, and beyond, just to do it. So, it was a decision that we made, and you often don’t get to write your own ending and when you’re gonna end. That was another amazingly generous thing that the studio and network allowed.

How close would you say this final season is to what you thought it might be, and how close is the ending of the series to what you thought it might be?

ROTHENBERG: What I would say is that tonally and emotionally, the ending is close to what I thought it might be. There were a couple of competing ideas that had various shades of darkness in them, but this is the one that we were aiming for, emotionally, all along, or at least I was. But truthfully, when we started, we didn’t know that we were gonna have a series, let alone seven seasons of one. Things evolve. Every season, we like to mix it up, so every season was a new adventure. Some of those seasons had to end without us knowing if there was gonna be more, so needed to thread the needle of doing both a potential series ending and a season ending, all in one. Season 5 is a good example of something like that. And then, you get together with these really smart, talented people in the writers’ room, and things get better and evolve.

What are the challenges specific to doing an episode, in your last season, that also is meant to serve as a backdoor pilot for a possible prequel?

ROTHENBERG: That was exciting. The truth is that we were breaking the season before I had agreed to do a backdoor pilot, to keep the show the show going and we weren’t sure what it should be. There was an episode in the show that we had already been planning to do, and as (writer/executive producer) Kim Shumway and I started talking about what this new show could be, we realized that there was a perfect springboard into a potential Grounder origin story would be. And so, because it fit so well into the blueprint of our season anyway, it answers a lot of questions that are needed to be answered, series wise, and certainly fills in some blanks, this season, too. Without that episode, the story wouldn’t be complete, so it did both of those things, at the same time, in a way that we thought was relatively easy, actually. It wasn’t easy to write, it wasn’t easy to shoot, and it wasn’t easy to produce in a COVID world, but narratively, it definitely fit.

If that series does go forward, is that something that you’ll also be the showrunner for?

ROTHENBERG: Yes. If that series goes forward, and we feel pretty good about it, but you never know what’s going to happen, I will definitely be there to put it on its feet, at the very least.

The final season of The 100 airs on Wednesday nights on The CW.