Every year, The 100 finds a way to reinvent itself while staying true to what makes the CW drama so highly addictive. For its third season, creator Jason Rothenberg does so by expanding the world of the ground even further with the introduction of the ruthless Ice Nation, while turning all previously established alliances on their heads through rampant unrest and civil war.

TVGuide.com spoke with Rothenberg about how he creates the detailed, dangerous world of The 100, what our heroes will be facing this season and, of course, what's next for Clarke (Eliza Taylor) and Lexa (Alycia Debnam-Carey) when they finally reunite following Lexa's betrayal.

There are so many moving parts on this show. What's the biggest challenge for you when sitting down to plot out a new season?
Jason Rothenberg:
The biggest challenge is usually "What is the story?" I'm always trying every season to do something totally different that at the same time feels of the show. So that's challenging. I have a lot of crazy ideas that just don't work, so trying to find the thing that is both outside the box and inside the box at the same time, if that makes any sense, is hard. But so far I think I've been lucky in that those moments have happened where I'll have the crystallizing idea that I'll sort of then build the whole season around. Then the writers come in and we add all the details and flesh to the bone. But so far I've been lucky in that the Mount Weather story in Season 2, the stories that we're telling this season have all held together from beginning to end. I love the idea that when I come in in the beginning of the season I'll say, "This is how it's going to end, and we have to get to that ending, and here's what the big crazy midpoint moment is." When those ideas last from first day to last day, that's usually because they're pretty good ideas.

One of my favorite aspects of this show is the way it depicts commingling and cultural assimilation of different societies. How much research do you do when crafting this kind of story and building out the different cultures?
Rothenberg:
Yeah, some. I think most of it is just what do I think is cool. The world-building part of the show is one of the best things about the show in my opinion and it's one of the things that I enjoy the most. So getting to create this universe from the language to the wardrobe to the tattoos to this year we obviously get pretty deep into what the grounder spirituality is and means. All of that is pretty awesome. So yes, we do some research as to how societies have evolved in the past but for the most part it's fiction.

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We are finally introduced to the Ice Nation this season. What should we expect from them and their motivations?
Rothenberg:
The Ice Nation are militaristic, atavistic. They very much want to expand. They do not like the deal that they made to join Lexa's coalition in the first place. They did that out of necessity because Mount Weather was just as big a threat to them as it was to the rest of the clans. Lexa had that big bad out there that she was able to motivate 12 other clans that to overcome those personal needs to join together. It was never harmonious, but it was at least something. Then in one afternoon Clarke took Mount Weather off the table and suddenly that big bad that was out there that kept the Ice Nation and the Tree Crew from each others' throats was gone, and that old animosity this season begins to bubble back up and cause a lot of problems because the Ice Queen (Brenda Strong) wants everything.

I love how Clarke and the Ice Nation's Roan (Zach McGowan) are both warriors who have been isolated from their people, but are also fighting for what's best for their people. How will we see their dynamic and relationship develop as the season progresses?
Rothenberg:
By design we have these two characters who, for different reasons - Roan was banished, Clarke put herself into exile by choice - are both in exile and they are both warriors and they are both fiercely loyal to their people. I think one of the ways that we watch it grow, even as early as the first episode or two, is just the realization of that - that they do have a lot in common. We see from the top that Roan is not the scary guy that he appears to be when he first steps on the screen at the end of the premiere.

The last time Clarke saw Lexa, Lexa had betrayed her. When they come together again, how will we see them try and move forward from that?
Rothenberg:
Obviously, Clarke is pissed off and is not going to get un-pissed off any time soon. But I think eventually she will realize that had she been given a similar choice, that she probably would have done the same thing. In fact, she realizes that she did. Because Lexa's choice to abandon Clarke and essentially leave Sky Crew to die at the mountain to save her own people, albeit shortsighted perhaps in the eyes of some, was very, very similar to Clarke's choice in the finale last season to pull the lever and kill all of the people that had helped them ... in order to save her own people. That was kind of the theme of the entire season, which was how far can you go and still be the good guy in order to save your people. Lexa had that choice in [Episode] 15. Obviously, it landed very emotionally for both of them, but especially on Clarke. In [Episode] 16, Clarke had a similar choice and I hope that over the course of the first part of the season, Clarke will eventually come to see it that way. If she can't, then they'll never figure out a way to make peace with each other.

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Do you think there's any hope of a romantic reunion between Clarke and Lexa?
Rothenberg:
I think people will have to tune in and find out, but certainly it was developing that way last season. Lexa, I think it's safe to say was sort of - I won't say love at first sight with Clarke, but it definitely was a bit of a thunderbolt moment for her when she first saw Clarke. For Clarke, it developed a little bit more slowly, but by the end I think it's safe to say that they were very much intrigued at the possibility of a romantic relationship. And then Lexa did what she did in Episode 15 and abandoned her. So that's kind of a high bar to get over. But like I said, if she can figure out a way to reconcile it as something she might have done herself, then I would say definitely that could happen.

The Sky Crew discover a new faction of Ark survivors this season, but assimilating them into the Arkadia camp isn't easy. What can you tell me about the power struggle that ensues?
Rothenberg:
This season is all about civil war on some level... As you point out, a new station is integrated into the population that had already been there. Around Lexa's table too, the clans are at each other's throats and that begins to threaten the existence of everyone both internally and in each place. The hope is that they'll be able to overcome that on both sides before they're destroyed by it or destroyed by external forces. So yeah, they find another station that actually survived the landing... That group had their own experience on the ground and as it turns out that group's experience is 100 times, if possible, worse than what our heroes the 100 went through in Season 1. They landed in the Ice Nation so they've been dealing with some bad stuff. Its informed their world view and it affects the way they look at all Grounders and it causes problems as they try to get integrated into the society at Arkadia, lead by Abby (Paige Turco) and Kane (Henry Ian Cusick) when the season begins, that's trying to make peace with the Grounders. They're still trying to find a way to live together with their neighbors whose land their essentially occupying. So in comes a group that doesn't see a sort of differentiation between Grounders or clans. It's just they're all bad. So that becomes quite the area of conflict going forward.

Lincoln (Ricky Whittle) is stuck in the middle between the Grounders and the Sky Crew. How will we see him balance his loyalties and attempt to maintain the peace?
Rothenberg:
Had this new group not come in, it may have been a lot easier because Lincoln is a bridge character and he is somebody who sees things the way that Kane, Abby and Clarke see things: a way to live together and use the best parts of both groups' abilities or skill sets or technologies together to make everybody's lives better. Whereas the other side of that coin are the people who can't ever see past the fact that he's a Grounder. Obviously, he's in a relationship with Octavia (Marie Avgeropoulos) and in an interesting way she's going the other way. The more that Lincoln is trying to prove that you can link arms and work together to a common goal, the more that she wants to leave. This is in not a society at Arkadia of people who did anything for her. The rules up on the Ark made her hide under the floorboards for 16 years anytime someone came knocking at her mom's doors. Then when she was discovered, [they] floated, executed, her mother and essentially locked her up and threw away the key and sent her down to the ground to die. It's only since she's been down on the ground and a part of Grounder culture that she's found an identity and she doesn't want to give that identity up, which will also be difficult for her when a new group of people who look at all Grounders negatively start to move into town.

The 100 returns Thursday at 9/8c on The CW.

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