This interview was conducted during the 2023 WGA and SAG-AFTRA strikes. Without the labor of the writers and actors currently on strike, the series being covered here wouldn’t exist.
Adventure Time has been one of Cartoon Network’s popular cornerstone franchises during the 2010s. Its impressive fanbase widely celebrates this show for its exciting adventures, expansive lore that spans thousands of years, and loveable characters. The original Adventure Time focused on the tales of Finn “the Human” Mertins (Jeremy Shada) and Jake the Dog (John DiMaggio) as they venture throughout the fantastical world of Ooo. Alongside Princess Bubblegum (Hynden Walch), Ice King (Tom Kenny), Marceline (Olivia Olsen) and BMO (Niki Yang), Finn and Jake embark on several quests like defeating evil vampires, going island-hopping, and stopping a god-like death entity named the Lich.
While Adventure Time primarily focused on Finn and Jake, there were some stories involving gender-swapped versions of the duo: Fionna (Madeleine Martin) and Cake (Roz Ryan). Made up from the Ice King’s mind, Fionna and Cake had their own journeys in their little world starting in the third season of the original show. Slowly but surely, the two became another fan-favorite pair just like Marceline and Princess Bubblegum. Now, they’ve finally got their chance to lead their own quest in Adventure Time: Fionna and Cake.

In order to get a better sense of what’s in store for Fionna and Cake, we had the chance to talk to executive producer and showrunner Adam Muto. A longtime Adventure Time veteran since 2008, he’s been with the franchise in its early beginnings and worked alongside other Cartoon Network creators like Rebecca Sugar, best known for 2013’s Steven Universe.
In our exclusive interview, we get to discuss the impact of the original show’s Fionna and Cake on the fanbase, how Adventure Time: Fionna and Cake came to be, and how the thematic purpose of the multiverse plays an important role in the journeys of the duo and Simon Petrikov. Plus, we dig deeper into two characters who fans are very excited to see: Marshall Lee (Donald Glover) and his pal Gary (Andrew Rannells) (who you might’ve seen in this trailer). Check out my interview with Adam Muto down below!
THH: I want to talk about the inspiration behind Fionna and Cake first because these two have become big fan-favorites. I also saw that they were originally based on Natasha Allegri’s original sketches. How did these two characters come to be?
ADAM MUTO: Yeah, it’s basically how you understand it. Natasha [Allegri] took that trope and made the designs on her own initiative. I think [Pendleton Ward] just saw them and thought it would be cool to work into an episode and I don’t think it was more complicated than that. I think it was literally like, “Hey, these look cool! Maybe we can make an episode from that.”
THH: In addition to that, since Fionna and Cake are really popular, what was the initial thought process to have this duo lead their own show?
ADAM MUTO: I think because they’re popular among some fans, but they haven’t actually been in that many episodes so we didn’t really show a ton of them outside of the context of Adventure Time, their relationship, and their mirroring of Finn and Jake. I think it gave us an opportunity to differentiate them as their own characters and separate them, hopefully, and make it distinct.
They were born of the relationship of Finn and Jake and they don’t necessarily have to always be like that. I think that was interesting to me like, “How can we have them seize their own narrative and not just be, you know, girl versions of Finn and Jake?” [laughs]

THH: I’ve seen how the entire fandom has grasped on Fionna and Cake with their art, fanfictions, and cosplays. It’s really similar to how Ice King manifests Fionna and Cake as his versions of Finn and Jake. How did you take that all in while you were developing this show?
ADAM MUTO: It’s always inspiring to know what we’ve made had inspired people to make their own stuff. We didn’t want to try to incorporate it further than that like, “Here’s our commentary on fanfiction. What’s good fanfiction? What’s bad fanfiction?” It definitely is playing into the idea of what is important when it comes to canonicity because your enjoyment of something might be completely different than whatever the canon explanations for things are.
That idea used to be something I didn’t know how to approach, but now I’m just like, “Okay, yeah, go ahead!” It doesn’t need official input to be valuable or to be enjoyable for like a huge group of people. It’s hopefully saying the canon versions of Fionna and Cake don’t have to exist as we’ve known [them] and they can be so many different things. We can’t show every single version of that like every coffee shop version [alternate universe] or every fanfiction that something’s come up with.
We wouldn’t try to mirror that, but we’d also say like, “That is what fiction can be and sometimes has to be when you don’t see either yourself represented or the thing you want out of it isn’t necessarily what’s there.” That’s kind of a testament to the characters themselves more than the show. There’s so many different [laughs] versions of what people get out of fanfiction so I don’t want to claim there’s one reason why anything’s happening!
Just the idea of a multiverse feels like you [should] use it to explore different aspects of the characters rather than slightly different versions, you’re trying to give stronger contrasts. That’s how we’ve approached these different worlds too. Instead of one thing [being] slightly different, we’re like, “Okay, let’s just make it a completely different genre if we could.” From episode to episode, we try to maximize the opportunity because it’s a chance to show different things, but there’s such a gimmicky version of that. We really wanted to make sure it stayed grounded and see how are these characters different from the characters we know and what do Fionna and Cake take from them.

THH: Speaking about these different worlds, most fans are accustomed to the Ooo that Fionna and Cake are placed in the original series. This show transitions that into a more modern, realistic world similar to ours. How does that play into the thematic idea of change?
ADAM MUTO: I should make it clear that the world that Fionna and Cake live in the beginning isn’t our world necessarily. It’s more the world that Simon [Petrikov] left behind. It’s kind of like a very ’90s version of his world, but it’s also sort of incomplete so the details aren’t totally filled in. You can’t really imagine as much as the Ice King would put in his very normal brain so it’s a limited world.
There’s parallels we could say, “Oh no, this is a Matrix knock off.” But, we also want to make it seem like this world is very boring compared to Ooo in a lot of ways. So if she got a glimpse of what we should be like, this would be the worst place to be. We also wanted to make sure this world, on its own, has value and that’s why there’s still episodes there with the characters that were left behind so that it’s not just pure escapism.
[Fionna]’s closed off herself from the world that she does live in. Maybe it’s not as magical as it will be better if she kind of engaged in it.

THH: Especially with the multiverse, it also feels representative of embracing the imagination and fantasy. How does that influence Fionna and Cake’s journey throughout this show?
ADAM MUTO: I think it affects how Fionna approaches the different worlds. She has a set idea of how things work in a magical world she hasn’t been to because she’s read books and she’s played games. She ends up actually making things worse in a lot of worlds because she’s bubbling her way through and making a lot of assumptions about these things based on fiction. It gives her the wrong impression of how she should be acting and she ends up treating a lot of people as NPCs to her meta narrative.
Cake is different because Cake is magical, but she’s been relegated to being completely non-magical. She’s trapped in this body that can’t do the things that it used to be able to do. I think her journey is to regain something she should have and that it isn’t necessarily about “there’s no place like home.” It’s like, “No, you should actually be able to be what you want to be if there’s a way to do it that doesn’t mess up everyone’s lives.” So, that’s slightly different than what Fionna is going through.

THH: In addition, there are a lot universes that fans picked up on such as Farmworld and this vampire-ruled universe. How was that conceptualization process like and were there any other universes that were made, but didn’t make it?
ADAM MUTO: I think we made a list early on like, “Okay, what’s the maximum number of things we can visit? What have we already established like Farmworld and one of the later ones based on wishes?” A lot of times, they look really cool as concept art, but then you’re struggling to figure out why would you spend more than a couple of seconds in this world.
You could have a montage with a billion different worlds and that would be interesting. But, it’s more interesting to see them walk around in that world and interact with it. That kind of dictated which ones we eventually settled on because it felt like it’s not as meaningful if it’s just cool looking and different, but there’s no personal connection. We definitely knew we couldn’t go to a billion of them in 10 episodes.
Originally, we had some ideas like maybe they go to Flapjack and they spend an episode being in Flapjack’s world. [laughs] But maybe if you had like a 20-episode series, you could get stuff like that. For this one, we tried to make and focus around certain characters opposed to the laws of the world because it’s only satisfying if you have a story to tell in those worlds.

THH: With all these different universes in play, there’s also so many variations of Finn in this show. What’s the likelihood of Fionna meeting the original Finn?
ADAM MUTO: I mean, she met a Finn! [laughs] I don’t know because it’s tricky because that would bring it back to how we’re made similar. I think maybe now it might be easier now that the series is made, but originally it got really hard when we were making Fionna and Cake stories because we’re like, “Is this a cross over? Like what would that be? Do they just wave at each other and that’s the crossover?”
There’s that fanfiction aspect to that where you could do something. But, it also felt like it’s hard to make a story where you have [an episode] especially with the characters that were originally established. It’s two [versions] of the same character and they’re just walking in tandem with each other. How do you connect and make that more interesting?

THH: Aside from Fionna, we also have Simon Petrikov, who’s extremely important in this show as he’s learning to accept to live without Marceline and Betty. Given the what-if premises of the show, how does acceptance play into Simon’s journey?
ADAM MUTO: Simon has a very different starting point than Fionna and Cake because he’s sort of in what would traditionally be the end of this journey where he’s gone through hundreds of years of suffering and cast out of time. He’s not looking for anything at the beginning.
He’s just like, “This is not working. None of what I’m doing is working and I’m basically ready to give this up. I had this thing that was done on my behalf, that was too big to repay and how could I ever live up to that?” It was good to keep him there throughout his first appearance in that episode where he’s able to put on a brave face but inside he’s empty. It’s about him rediscovering his own value outside of being the Ice King and outside of being romantically.
He has to find this new sort of existence that isn’t tethered to either of those things. It’s a different story for him because he’s trying to find what life is about whereas Fionna and Cake are trying to find out the nature of their existence and who they are. He knows who he is, he’s just not really happy about it.

THH: Speaking about romantic relationships, I’ve seen a lot of fans coming around and resonating with Marshall Lee and Gary, especially given these hints in the trailer. How has it been transitioning from Marceline and Princess Bubblegum to Marshall Lee and Gary?
ADAM MUTO: We just call him Gary because like, how do we call him Gumball in a normal world? We just reduced his name to Gary Prince, so their ship name’s Gary-Marshall, which we realized later. [laughs] But, it gave us an opportunity to show a meeting because that’s something we never really done with Marceline and Princess Bubblegum. We’ve alluded to past adventures, but never actually how they met each other and the very, very early days we left vague.
So rather than just show an explicit episode like, “here’s exactly how they met and tripping over each other,” we used Marshall Lee and Gary as a way to tell that story, but to also make it theirs. It’s not like this is exactly how Marceline and Princess Bubblegum met, but it’s like they might’ve had a dynamic similar to this when they very first met and using Fionna’s solipsism where she doesn’t even introduce her friends. She’s so closed off that she has friends, but it doesn’t even occur to her that they could actually be overlapping circles.
They’re also not the same exact characters. Gary’s not necessarily as authoritarian as Princess Bubblegum or as together and commanding. He’s just got some of the ambition, but is a little bit more nervous. Marshall Lee has got some of the cool aloof elements of Marceline and the same issues with his parents and the expectations placed on him, but he’s also not super-powered. It gave us an opportunity to show different aspects of how we’d established Marceline and Princess Bubblegum.

THH: Before we wrap this up, I just have one final question. Will Fionna and Cake or the world of Adventure Time return in the future?
ADAM MUTO: I don’t know. I hope so in some way, but it’s very out of our control. It depends on how things do. We’ll keep pitching stuff, but it always feels like a craps shoot. I feel really fortunate that we were able to do this after the original series ended so keep your fingers crossed. This was already pretty extremely unlikely that we got to make this and I think we’re really fortunate that we were able to do this!
Adventure Time: Fionna and Cake streams on August 31 on Max.