The CW drama series The 100 is back for its fifth season, with Clarke (Eliza Taylor) struggling to survive on Earth while her friends in space think they may have finally figured out a way to get back to the ground. At the same time, a new ship of prisoners – this time made up of some really bad criminals – has landed and is led by a woman (Ivana Milicevic) whose motives do not immediately reveal themselves, but clearly are a threat to anyone that crosses her path.

During this 1-on-1 phone interview with Collider, showrunner Jason Rothenberg talked about what fans can expect from Season 5, how this season started to take shape, why the six-year time jump provides a bit of a reboot, the challenges of the premiere episode, the threat of this new group of prisoners, the eventual reunion between Clarke and Bellamy (Bob Morley), which character has had the biggest character journey in the six years that have passed, the biggest threat in Season 5, and his plan for the series, going forward. Be aware that there are some spoilers discussed.

Collider: How close does this season look to you what you thought it might look like, if you actually got to this point?

JASON ROTHENBERG: When we first started, when I wrote the pilot, I was just trying to get a series order. I hadn’t thought about anything. I knew there were people on Earth, obviously. We had the spear come out of the woods and kill Jasper. He literally was dead in the pilot script. That didn’t end up happening and that spear barely missed his heart. So, I knew there were survivors on the ground, but I didn’t have any idea what that culture was. Ultimately, I fairly quickly began to build out the world and what it was. Every season, as I’m breaking, with the writers, the season that’s currently being produced, I’m always thinking about what the next season is, so that we can begin to plant the seeds of what that might be. That way, the ending can take us there. And also, to keep it creatively interesting for me, I like to change it up, radically, every season. But we’re beyond the point that I initially envisioned, as an end point, at this moment. That’s fine. It’s elongated, in terms of where the story’s going now. Wait till you see where it goes, at the end of Season 5. We’re talking about a change that will make the last change look like nothing. It’s really, really exciting, where it could potentially continue to go, and that’s how we keep it interesting for all of us, and the audience, too.

Are you at a point where you have to think about how much further, realistically, you see the show going? Do you have a plan for a certain amount of seasons more, or are you taking it season by season?

ROTHENBERG: Well, yes and no. I definitely feel like I have a plan in mind. I’m not gonna say what the plan is, at this point, but it does have this nice ability to elongate, and by that, I mean we can push that out, as far as we need to or as far as we’re lucky to. I’m not sure how much more I have in me. Its been a very, very long run. I feel like I’ve been blessed in playing with winnings, as they say in the casino, for awhile. At some point, it’s a business decision, as much as it is a creative one. I also don’t want the show to stick around, past its sell by date. I feel like, as of now, it functions as a really great five-season show, and I have a great idea for Season 6. As long as we continue to come up with what I think are great ideas and stories I’m excited to tell, and that keep everybody inspired, then we’ll keep doing it.

Does this season feel like a re-invention for you, especially as the showrunner, or does it just feel like the next step in the story?

ROTHENBERG: It feels like the next step in the story. Every season for me is so different. The story of the season is always its own unique thing. This one had some added obvious evolution, in the idea of the time jump and how different the characters can be, based on those six years spent changing while we were away, so in that way, it is a little bit of a reboot. It’s definitely presented interesting challenges that hadn’t existed in prior seasons, but there were things that we were excited about and I feel like we handled well. The audience will be the judge, but I think this season is easily one of our best.

What were the challenges you were most excited about, in doing a premiere episode with really only one actor for the majority of it, and what were the challenges that you were dreading?

ROTHENBERG: I never, ever was dreading. I always thought, “Oh, my god, this is a huge idea and it’s totally unique and not like anything we’ve ever done before.” I feel like the idea of her being the omega woman – the last person on Earth – was baked into a cake, in terms of the way we ended Season 4. The idea of getting to play with that, and getting to see Eliza [Taylor] in that tour de force, was really exciting to me. Obviously, we all know how good she is, but I still think she hasn’t even scratched the surface of how good she is. This was really an opportunity to get her to shine and showcase her for 20 minutes. Not a lot of actors could pull that off. She’s special.