Beginning life as an irreverent animated series mostly geared towards kids, Adventure Time has won over people of all age groups with its mix of absurd humor and heartfelt moments. Over time, the series has dealt with a number of mature themes and teased out a dense mythology for the land known as Ooo. Peppered throughout the many adventures of Finn the Human and Jake the Dog have been deep dives into the tragic past of the planet they inhabit and the origin of many of its key players.

Over the course of hundreds of episodes, miniseries, and comics, we’ve had the curtain pulled back on a number of characters and events that are more than what they initially seemed. With the recent announcement that the show would be ending at the conclusion of Season 9, many fans are hoping a number of the show’s core mysteries get some further illumination (and some of their theories get proven true). Here are 13 Things We Need To See Happen Before Adventure Time Ends.

13. The Great Mushroom War

Aftermath of the Great Mushroom War from Adventure Time Intro 13 Things We Need To See Happen Before Adventure Time Ends


Teased early in Season 1, the Great Mushroom War is eventually revealed to be the cataclysmic event that transformed our world into Ooo. While it’s still unknown how close the former planet was to Earth as we know it, there have been plenty of hints (including in the show’s intro) that life was once much like it is today. Then, what appears to be a nuclear war erupted and destroyed almost all life. In its place, new forms of sentience arose, new societies were formed, and even a few humans and dogs began to pop up around the fractured planet.

Based on various pop culture references and bits of technology we see (such as early Apple computers and discussion of the Internet), it appears the world war may have happened sometime in the late ‘90s or early ‘00s. We’ve seen some teases of the previous world thanks to flashbacks to Simon’s life before the apocalypse and with the recent introduction of the current Ice Elemental. It would be fascinating to travel back and watch the events that brought us the show to where it is now unfold, further cementing the dark and mature undercurrent by exploring the horrors of war and the fallout of a nuclear devastation.

12. Legend Of The Lich

 13 Things We Need To See Happen Before Adventure Time Ends


One result of the Mushroom War that needs its own miniseries is the rise of the villainous Lich. We know from the alternate Farmworld episodes, which tease a reality where an apocalypse never occurred, that the mushroom bomb that wiped out most of the Earth unleashed the entity known as the Lich. The rogue marks one of the show’s earliest examples of pulling the macabre into this absurd world. With decaying clothes, devilish horns, and skin hanging off its skull, the Lich is evil incarnate.

The idea that this creature is the outcome of a nuclear fallout is an even more intriguing concept. Though the Lich has never been shown to be as sympathetic as villains like the Ice King– thus hardly meriting a POV miniseries– his rise and the very idea of a “mushroom bomb” are massive parts of Ooo’s lore that have only just been touched on in the series so far. Considering the Lich– like Bubblegum, Marceline, and Ice King– has been around for the thousand years since the war, it would be fascinating to see what he’s been doing this whole time, what drives him, and how he’s interacted with Ooo since its rebirth.

11. What Happened To Finn’s Parents?

 13 Things We Need To See Happen Before Adventure Time Ends


Another core mystery of Adventure Time is where exactly Finn came from. He appears to be a fairly standard human who ages normally, and we know he was being raised alongside Jake and his family. But we don’t know much about is Finn’s parents. Well, that is until we met Martin Mertens.

Teased a few times before finally appearing in Season 6’s “Escape from the Citadel,” Martin is Finn’s absolutely terrible father. Martin couldn’t be more the inverse of Finn, as he’s cowardly and self-serving. The very fact that he left his infant child alone in a post-apocalyptic world is evidence enough of his bad character.

His appearance has allowed the show to dive into some of its most mature themes, showing that fathers (and parents in general) aren’t always the magical heroes other kids’ shows would have us believe. But while we’ve come to learn more about Finn’s deadbeat Pops, we still know nothing of his mother. It’s almost guaranteed that we will encounter the Mertens matriarch before the series ends, especially as the upcoming miniseries Islands is teasing some answers to Finn’s past. Either way, a nice, long look back at the history of Finn’s parents would help explore both our hero and the earlier days of Ooo.

10. The Story Of Susan Strong

Susan Strong in Adventure Time 13 Things We Need To See Happen Before Adventure Time Ends


Dating back to an eponymous second season episode, Susan Strong is introduced as a possible tease that Finn isn’t the only human still living in Ooo. We discover that Susan and her people aren’t quite the same as our hero, but the episode– and her future appearances– open up a lot of questions. Many of these come to a head in the penultimate episode of Season 7, “Preboot,” where Finn, Jake, and Susan encounter the cybernetically-enhanced Dr. Gross. When Finn acts surprised that she appears human, he addresses many fans’ questions in a nice little meta joke: “You’re human?! I thought I was the last one! Well, me and Martin. And Betty. And sometimes Ice King?”

All of the examples remind us that over the years, we’ve met a few other humans still in existence (along with plenty of humanoids and former members of the species like Marcy). Jake then tops off Finn’s list of humans with: “ Yeah, and I still have questions about Susan.” While we won’t spoil the show’s recent finale, the two-parter teases plenty of interesting backstory for Susan. Some of that will be explored in the upcoming spinoff Islands, premiering next month and picking up the threads of these episodes. Hopefully, the miniseries will finally give us the answers that fans, Susan, and Finn have been seeking for so many years.

9. The Story Of Finn And Jake Growing Up Together

Baby Finn with Jakes Parents Margaret and Joshua on Adventure Time 13 Things We Need To See Happen Before Adventure Time Ends


While we know more about Jake’s family than Finn’s, they still remain a bit of a mystery as well. Their story is even more important to see as it connects to how Finn grew from an orphaned baby to the hero we meet at the beginning of Adventure Time. We know that Jake’s father Joshua was similar to Martin in some ways. He drove the boys to fight and used various schemes and games to teach them lessons (acts which drove Jake’s brother Jeremiah into a life of hermitism). Still, Jake’s dad appears to have loved his family. Seeing more of his story and getting to know his underrepresented wife Margaret would provide us with a lot of context for our two protagonists.

Like Finn’s father, Jake’s dad provides the chance to explore some adult themes, since both he and his wife are deceased. It’s been danced around, but the death of both of his parents is surely something tragic from Jake’s past we could explore, and must have been especially rough for Finn, who wasn’t yet a teenager. Adventure Time has never shied away from delving into the pain of real life, so traveling back to the moment when Jake, Finn, and Jeremiah lost their parents would make for some harrowing television.

8. The History Of Ice King’s Crown

Gunther as Urgence Evergreen with Ice Kings Crown 13 Things We Need To See Happen Before Adventure Time Ends


Simon Petrikov, better know as the Ice King, is one of the most intriguing characters in the series. When we first meet him, he’s a fairly standard (and moronic) villain. Thanks to a number of flashbacks, home videos, and his connection to Marceline, we eventually learn a great deal about his tragic past. Possibly the most interesting part of his backstory, and one of Ooo’s oldest artifacts, is his magical crown.

Both the source of his power and insanity, the crown was created by an Ice Elemental named Urgence Evergreen thousands of years ago. The Elemental bears a striking resemblance to Ice King. We also learn that the transformation Simon undergoes comes from the tinkering of Gunther, Evergreen’s pupil, whom the Ice Kingdom’s many penguin citizens are named after.

In Season 7, “Broke His Crown” takes this a step further by showing Gunther and a number of other former crown-wearers, including Simon, exist inside the circuitry of the crown. This revelation helps to explain Ice King’s mood swings and varying personalities. It also opens up a whole new mystery box in need of exploring.

Bolstering that intrigue is the recent emergence of Patience St. Pim, the reincarnation of Evergreen and the current Ice Elemental. Hopefully, she’ll return in the future to help explain what she was up to in her past life and provide us with some more insight into both Ice King’s crown and his madness.

7. The Origin Of Ooo

Earth as Ooo in Adventure Time 13 Things We Need To See Happen Before Adventure Time Ends


While the show and creators have both made it known that the world on Adventure Time was once similar to our Earth, there’s still much about that transformation we haven’t seen. In fact, we spend most of our time in the Land of Ooo, with the rest of the planet yet to be fully explored. On occasion, our heroes travel outside its confines, but it would be interesting to see how the rest of the world has managed since the Great Mushroom War. We get to see a bit of Ooo post-war, thanks to Marcy’s and Simon’s various flashbacks, and even get a chance to watch Bubblegum rise out of the primordial candy ooze during those days.

Thanks to a number of trips to space (and Jake’s daughter Charlie literally globe-hopping in “Daddy-Daughter Cards Wars”), we know that a sizable chunk of the planet is missing thanks to the mushroom bomb. The Land of Ooo appears to exist very near or even inside of this crater, in what used to be Europe (which is odd as all the past residents have American accents). We also get another little wrinkle in “Simon & Marcy”, where a food truck has a plate registered in the Wut-Wut State, teasing that the pre-apocalyptic world was a bit different from our own. All of these tidbits make it even more crucial that we explore some small chunk of the one thousand years between the Mushroom War and modern day Ooo.

6. Who Built The Tree Fort?

Finn and Jakes Tree Fort from Adventure Time 13 Things We Need To See Happen Before Adventure Time Ends


On a smaller scale, there’s the mystery of where Finn and Jake’s Tree Fort home came from and who built it. A number of episodes have shown the Tree Fort in the future (even taller and blooming), and in the past (as a sapling where Finn’s past life Shoko dies and leaves her skeleton). The deed’s passed through the hands of Marceline and Jake’s father-in-law, but we mostly see if as it stands now. It not only serves as the home to Finn, Jake, BMO, Shelby, and N.E.P.T.R., but houses their weapons, treasure, and Lorraine the Chicken.

Over the years, we’ve learned of the secrets deep beneath its pond, the history of Shoko, and even traveled into the walls a number of times. Given its hidden depths and deep backstory, Adventure Time wouldn’t be complete without a journey back to the Tree Fort’s construction to learn whether Finn and Jake made it themselves, or if another band of heroes built the fort on the outskirts of the Candy Kingdom to keep watch in their day.

5. The Writing Of The Enchiridion

The Gems Inside The Enchiridion on Adventure time 13 Things We Need To See Happen Before Adventure Time Ends


One of Ooo’s oldest artifacts, the Enchiridion is a book of immense power and a number of rules and tips for heroes. It features chapters on subjects as diverse as “The Cyclops” and “How to Kiss a Princess,” and is meant for only the truest of heroes. Mostly tied to Finn, the book, like many things in Ooo, actually has a connection to Ice King himself.

Back before the Mushroom War, Simon discovered the tome in Pakistan during an archaeological dig. He then donated it to a museum, not knowing his future connection to the book. Turns out it can be filled with various powerful gems, held by the monarchs of Ooo, to unleash great power. The Lich attempted to use this power to cause chaos across the multiverse, forcing Finn to destroy the book. However, it’s been showed to still exist in alternate realities such as Farmworld, where the Lich unfortunately roams as well.

Given all the power and history the book has, it would be exciting to travel back to its origin and see the scholar or hero who first penned it. Not only would it flesh out a number of mysteries, but it would provide us with another glimpse of the magical world that existed long before the Mushroom War.

4. The Ballad Of Billy

Billy from Adventure Time 13 Things We Need To See Happen Before Adventure Time Ends


With all this talk of heroic deeds, it’s only fitting to spend a little time on the mighty hero Billy. Analogous to Finn in his youth, Billy is not only our hero’s idol, but one of Ooo’s greatest champions. Despite having given his life over to non-violence in recent times, he still provides us with a strong connection to the early days of Ooo. Like Finn, his stories could serve as some riveting action and a deeper exploration of what Ooo’s past looked like.

The story would also be bittersweet, as we know that the Lich eventually kills Billy (and wears his corpse as a suit, earning the show extra creep points). It would be a shame to not see the character, as voiced by Lou Ferrigno, once more before the series ends. Rather than remember him as a gross skin costume, we could watch one of Billy’s early adventures as a memorial to the fallen hero.

3. More Princesses (And Princes)

 13 Things We Need To See Happen Before Adventure Time Ends


One of Adventure Times’ best running gags is the deep bench of princesses (and a few princes) that inhabit the land of Ooo. If you thought keeping up with all the various kingdoms in Game of Thrones was tough, just try unpacking all the royalty that live in Ooo. There’s the key players, like Princess Bubblegum, Flame Princess, Slime Princess, and of course, Lumpy Space Princess. But it’s all the monarchs that pop up around the periphery that are a blast.

Hot Dog Princess, Bounce House Princess, Muscle Princess, Embryo Princess, Engagement Ring Princess, Gridface Princess, and the critically underused Skeleton Princess are just a small fraction of the rulers that we get to spend some time with.

The show has even gotten creepy and meta in equal terms with Princess Princess Princess and Princess Monster Wife, which both exemplify Ice King’s worst traits and align him further with Herr Doctor Frankenstein. Let’s hope before the series ends we get another chance to sit in on the annual Princess Day event introduced last season. It might not make for the most captivating narrative, but we wouldn’t complain if all 11 minutes of the episode were simply dedicated to listing off every bizarre princess the writers could come up with.

2. The Return Of Fionna And Cake

 13 Things We Need To See Happen Before Adventure Time Ends


First introduced in the season 3 episode bearing their names, Fionna and Cake are the gender-swapped (and in the case of Cake, species-swapped) versions of Finn and Jake that exist in a series of stories by Ice King. With four episodes to date, we’ve been able to watch them enjoy a number of adventures and see the denizens of their invented Ooo. There’s the Ice Queen, Marshall Lee the Vampire King, and Prince Gumball, the object of Fionna’s affection.

With two seasons to go, it just wouldn’t be right if we didn’t return to their alternate reality. Not only is it always a blast to spend time with them, but it’s fun watching the writers come up with clever variants of classic characters. The most recent highlight: Butterscotch Butler, the Butterscotch Scottish Butler. Now that’s just plain inspired. Also teased in their most recent appearance is the fact that Ice Queen has her own set of stories featuring the adventures of Flynn the Human Being and Jacques the Racoon. Here’s hoping we return to that tale as well, so we can get an answer to Fionna’s question: how did the Ice President get elected?

1. Finn and Bonnie, Sitting In A Tree

 13 Things We Need To See Happen Before Adventure Time Ends


The many mysteries of Adventure Time are ripe for exploration, but the show reached greatness thanks to its heart. While the relationship between Finn and Jake will always be the emotional center of the show, it’s our hero’s courtship of Princess Bonnibel Bubblegum that’s allowed the protagonist to mature. Though Finn can never hope to close the age gap between them (seeing as how P.B. is around a thousand years old), he’s grown a lot since they first met– from a curious and brave child to a seasoned warrior with a heart of gold.

It’s not that it’ll be a failure on the part of the show if we never see Peebles return Finn’s feelings, but it would certainly be a cathartic way to end the series. Instead of a climax based around a massive fight or the reveal of some key information, the truest way to end Adventure Time would be with a quiet moment of mutual affection between Finn and Bonnie (okay, and Jake too).

What do you hope happens before Adventure Time ends? Let us know in the comments.