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Fionna's world is an imaginary one inside Simon's head.
At the end of "Simon Petrikov", Cake enters the regular Adventure Time world via a portal from the back of his head, implying that the world we see in the first episode is, in-fact, not real at all even if the residents within are to some extent. We also see multiple instances of Betty throughout the first episode, such as a statue of her in the park or as an image on a newspaper, further implying that Simon may have some influence on the "real" world.- Semi-Confirmed. Fionna and Cake's world is inside Simon's head, but it's just as real as the rest of the multiverse. Having been put there by Prismo while Simon was still the Ice King.
GOLB will play a role in some capacity
It's clear that whatever Simon is trying to do to find Betty might involve GOLB in some way, and given how many fans were disappointed at how the Greater-Scope Villain of the series was presented, this could be an Author's Saving Throw too.- Somewhat Confirmed as the ending of the episode "Jerry" seems to show a portal to GOLB with his face appearing in the eye of The Lich, then fully Confirmed in the next episode where GOLBetty sends Simon into Ooo's futur, inside Shermy's body, to help him understand one of their relationships biggest flaws and how much Simon is worth as a person.
- Confirmed completely. GOLBetty shows up in "Cheers" to converse with Simon about what could have happened between him and Betty and to save Fionnaworld.
Flapjack is the original universe every other universe spawned from.
In the beginning it was just Flapjack's world and the Time Room, since Prismo said his world was always there. There are quite a few similarities between Flapjack, K'nuckles, Finn and Jake, to the point where it's almost uncanny. It's plausible that some adventurers who knew the duo got access to the Time Room, made some wishes and spawned the rest of the multiverse, and how would there get there? The ever elusive Candied Island. Fionna or Cake will ultimately save their world by wishing it saved.
A proper wish in the Time Room would authenticate the Fionna & Cake world, which would take it out of Simon's head and into the multiverse proper, allow it to regain its magic without Simon having to become Ice King again, and possibly even free Prismo from any impending punishment.- Confirmed, but not by Prismo. GOLBetty gives Simon a wish dandelion, which he gives to Fionna in her world via portal to allow her to wish her universe into being authorized.
One of the Universes Fionna and Cake will travel to will be Bee and Puppycat.
While so far each universe has been an alternate version of Adventure time … Fionna and Cake travelling to an entirely different franchise could serve as a big Wham Episode, it’s also possible that Fionna’s similarities with Bee is setting up this crossover.- Jossed.
Magic won’t be returned to Fionna’s world.
When the series ends Magic will not be returned to Fionna’s world … not because it couldn’t have been returned but because she realised that a mundane life isn’t as bad … with her also snagging the remote so that she can visit Ooo anytime she gets bored.- Semi-Confirmed. Fionna ultimately decides she likes her world better than the old one and magic doesn't end up restored to the world proper once the universe is authorized, but Cake retains her magic powers and multiple people from magical universes end up staying in Fionnaworld. The part about her snagging the remote is Jossed, however.
The story will span over multiple seasons.
With only four episodes left, we have a number of unanswered questions. Who is Prismo’s boss? Where is GOLB’s ranking on the cosmic hierarchy? This could theoretically be left unsolved, but it would be unsatisfying. Perhaps the main story will finish up, with a second season or movie tying everything up. Fionna and Cake’s Anti-Magic powers.
What if the reason why Fionna and Cake can cancel magic from the multiverse isn’t just because they belong to an “unauthorized universe” created by Prismo for himself, but also because both of them were accidentally summoned by using a ritual to summon Golb/Betty? Whenever they “glitch” the magic out from magical creatures, how it happens is similar to the time Golb “digested” all the Ice King and Betty’s magic, turning them back into their original selves in the original series finale. Fionna will lose an arm.
- Jossed.
Fionna and Cake sponge up magic instead of removing it
As indicated by Cake still being intelligent, the erasure of magic from their realm was not 100%. Given magic is treated like standard energy in AT rules, it's possible that their bodies, used to having magic, simply no longer have any and are trying to refill. Fionna accidentally sucks the magic out of the Farmworld dagger and the Winter King, and Cake sucked the magic out of the hot dog knightnote . Whether this magic will stay within them, dissipate, or be sent to their universe is anyone's guess. Simon will become the new wishmaster
- Someone has to do it. Prismo is locked away in a pocket-sized Tailor-Made Prison designed to contain deities, the main three probably can't break him out. The series has also never been one to let villains win for good, so Scarab probably won't end up getting his wish to become the new wishmaster either.
- It would give Simon a new purpose. He has no reason for existing other than hoping that someday he might see Betty again, and his depression proves he isn't doing well with that mentality of being useless and unproductive.
- Simon would be good at it. He understands the physical limits of the power thanks to Prismo being unhelpful in summoning Betty, and he knows the "legal" limits of the power thanks to his adventure against Scarab. Plus, as someone who had a full life, met many people, and had many experiences, he would be able to relate and connect to people desiring wishes, and could point them in better directions like Prismo did Jake.
- It would give Simon a way to be magical without insanity. This means Fionna and Cake could go home and be happy, but also wouldn't require Simon to sacrifice his sanity and mentality, nor would it ruin the few friendships he has with the inhabitants of Ooo.
- Jossed.
The curse of the Ice Crown is undone by love.
- The Winter King's crown stopped working and his magic failed utterly when he kissed Fiona.
- The Candy Queen was susceptible to the crown's magic because she hadn't experienced Marceline's love - note the ice Marceline that the Winter King created, suggesting the original was dead, and may in fact have died very young given the appearance of the ice clone.
- Simon Petrikov fully lost control of the crown's magic and lost Betty at the same time.
Fionna and/or Cake will glitch the Scarab out of existence.
For someone so obsessed with capturing those from the unauthorized universe, it would be a Karmic Death to be done in by the very properties of that illegal universe.- Jossed. While they do defeat him by using his crystal scythe to put him in an egg, ultimately he winds up being reduced to the Wish Room's janitor, becoming a shadow-like projection ala Prismo.
Simon will die, or otherwise get mortally wounded.
Throughout the episodes, we see many different versions of Simon die; The Winter King dying of rapid aging after his crown glitches out, the vampire world's Simon getting drained long before the events of the story, and the extinct world's Ice King dying on camera in a Freeze-Frame Bonus. All of these could very well be pointing to something very unfortunate happening to Simon, much like how the main show hinting at Finn losing his arm many times.- Jossed. Simon ultimately survives the series without much lasting harm.
Minerva is still alive in the extinction universe
Since The Lich's wish didn't kill any robotic or artificial life like BMO that means that it's possible Minerva is still around since her essence was uploaded into a super computer Baby Finn in the Vampireworld will still have the surname Mertens.
He will still be Finn, because that's what the world's locals heard Fionna call him, and the last name will be given in honor of the fallen friend who earlier took a liking to the baby boy. If there’s more than one season, one will involve Cake betraying Fionna and Simon.
It’s been made pretty clear that this Cake is, well… a lot more insensitive and kinda selfish compared to her previous self and especially a lot of Jake’s. This is noticeable at the start of the series, where she does stuff like rubbing it in Simon’s face that she thinks he’s lame compared to the Ice King, but it comes to a head in “Jerry” where, even after seeing how miserable being an Ice King can be, she’s still completely willing to put Simon through that even though Fionna has realized otherwise just because she doesn’t want to go back to being a normal housecat again. Now, the narrative seems to imply that the best thing for everyone is for the crown to definitely NOT go on Simon’s head and for Fionna’s world, by extension, to stay as it is in its normal state. But that won’t align with what Cake wants, and so once the dust has settled on the big battle and everything seems to be wrapping up, Cake will be tempted into getting her own magic into her despite her world staying normal in a terrible way: by stealing the Ice Crown and putting it on herself, which would cause her to turn into the Ice Cat/Snow Cat/Cold Cat/Etc. and the next season would be about her going crazier and crazier from the magic and Fionna and Simon having to track her down and talk her back down. Not only would this be super interesting because it’d sort of be looking at an example of “What would happen if Jake betrayed Finn?”, but it would actually be a nice little callback to Cake’s unique origins in this universe of having once been best friends with the Ice Queen before she had been given the cursed gem that turned her from a water nymph into her current self, a sort of ironic hell situation. Plus, I know we’ve seen the effects of the crown from Simon’s experience with it, but this could be a good way of letting us see the kind of magical madness firsthand from the wearers point of view as Cake goes crazier and crazier.- Unlikely. Cake seems happy enough with their world as it is at the end of the first season.
The Lich will become prominent in the final two episodes.
As early as “Fionna Campbell”, there were mentions of a mysterious Jerry from the magicless Banana Guards who were turned human. In “Prismo the Wishmaster”, The Lich is briefly seen in Wyatt’s Wish universe, staring directly at the viewer. In “The Winter King”, an infant version of the Lich is shown in the Baby World, and the Banana Guards in the Winter King’s world also spoke of “Jerry”. Come to the titular episode “Jerry”, we learn that Jerry is really the Lich. More specifically, the Prime version of the Lich. The Lich’s fate in the Vampire world is unknown, but given the existence of Evergreen’s Crown, he definitely exists. Plus, with the heavy amount of foreshadowing regarding GOLB, the Lich may take the chance to spread his devestation across the multiverse now that he’s finished with his own world. This may possibly be evidenced by the Lich’s Sickly Green Glow pupil appearing in his eye, his signature sign that he is active, before morphing into GOLB’s face. It is not out of the realm of possibility that the Lich may have been planning something for a while.- Jossed. He dies at GOLB’s hand early into “Casper and Nova”.
The female human Ash is still in Simon's head
We never see her again after she obliviously walks into the void left by Scarab's rampage. Because they were still in Simon's head at the time, Ash is trapped in his mind, slowly going insane. Simon will write a book based on the choose-your-own-adventure style futuristic book he in Shermy's body read with Beth.
He writes it in hopes of helping others down the road who may have the same kind of problem he once had. And, of course, further down the road, it'll be adapted into the futuristic style of book from the 1000+ time period, which will be the book that inspired the original. Explanation for the ending
The ending was left pretty vague what exactly happened. I think that Betty, sensing Simon wouldn't give up his journey to save Fionnaworld, used the GOLB reversion magic to turn the crown back to its wish-giving properties. Simon found the crown among the universal rocks in the void, and put it on, only his wish was to save Fionna's world. This, as a result, canonised the universe, repairing Scarab's damage and making his destructive actions illegal. Astrid is the author of Casper and Nova
Based on their ending sequence together, Simon seems to have told Astrid a lot about his journey, and this would include the tale of Casper and Nova, based on the book he read. Astrid's drawings also look incredibly similar to the two for what's supposedly just Simon describing their appearance from memory. It would make sense that she creates the designs and writes the book off what Simon tells her, then Simon reads the book in the future. A literary time loop. There is no Nova route
The reason the book rejected going back was because the only reason anyone would do so would be to go down Nova's route. Except that the author, either Simon or Astrid, knows that the book is specifically for the future Simon who chooses to go down the Casper path, and as such doesn't feel a need to write one that would never be seen and would be mostly speculation. Every Tetris Block in Golbs Domain is a Lich
In the infinite multiverse, some Lich’s destroy all life, and they all lose their purpose. Among them, some manage to reach Golb, and all rage against their god. And all of them are rewarded the same. Possible Season 2 plots
If there is a Season 2, some plots will be:- Finding out what happened to GOLBetty.
- They will visit more universes, including:
- A world where Marceline took the crown from Simon to become the Ice Queen and Simon became a vampire to help her through her madness.
- A world created by Scarab, with all the Stylistic Suck that it entails.
- A world where Patience St. Pim found the crown instead of Simon.
- A world where Gumbald managed to douse Bonnie with the dumdum juice.
- A world where Finn failed to stop the Gum War from happening.
- A world where Bubblegum succeeded in turning all of Ooo into candy elementals.
- A world where Finn and Martin were never separated, living their lives out on Founders Island with Minverva.
- Fionna meeting the mainline Finn.
- Fionna and Cake meeting other incarnations of Finn and Jake, including Shermy and Beth.
- Or alternatively, their own Shermy and Beth: a heroic rabbit girl and a "Kitten Prince".
- Something going awry in Fionna's world thanks to the fanfic written by the Ice Queen starring the Ice President.
- Fionna's parents show up.
- Also Gary's family, including the genderswapped Uncle Gumbald.
- Simon will start dating again now that he's moved on from Betty.
- Finn, Marceline, Bubblegum, and BMO (Simon's closest friends) finding out about Simon's adventures in other worlds and interacting with their gender swapped counterparts.
- More hints on how Jake died in the timeskip.
- How Lady Rainicorn coped with Jake's death.
The blocks surrounding GOLB are the things it has destroyed.
GOLB is a destroyer god. We've only seen it destroy anything onscreen once, that being Jerry. It's not impossible that this is simply how it "destroys" things. The last scene shown after the credits has some secret meaning to it.
The last scene shown has a green cube and red pyramid merging together to form an Apple with a white ribbon tied onto it. While it might seem strange at first, it likely has a secret meaning like many other things featured in Adventure Time previously did.- The cube is the same color as the blocks that surround GOLB, while the apple is the same color as GOLB itself. Perhaps the two are symbolic of the fusion we saw near the end, where GOLB seemed to fuse with the many blocks surrounding it.
Marceline died as a kid in the Winter World.
The desire to protect and keep her safe played a part in Simon's determination to resist the Ice Crown, and she continued to serve as something that grounded him. We see in the Vampire World that if Simon never had the crown, he would've been killed by vampires and never met Marceline, who became evil in that timeline. We see him make an ice sculpture of kid Marceline, but not a sculpture of her older self or even the real deal who probably would've intervened to help out Bonnibel. The reason why the Winter King is the way he is once he passed his insanity onto Princess Bubblegum is because he failed to protect her, and with her death, the last living link to the Ice King's humanity was lost. Also serves as a parallel to the Star. Big Destiny is responsible for the death of Finn's wife in Farmworld.
It's why Jay and Little Destiny ask to stay in Fionna's world when Prismo brings them in. Whether Big Destiny was directly involved or it was his actions that led to the death of Finn's wife, he's still responsible and Finn could never accept his son falling in love with Little Destiny. Therefore there was only one way for the star-crossed lovers to stay together (aside from suicide a la Romeo and Juliet) and that's to go somewhere that neither of their fathers can reach. Someone in Fionna and Cake's world will reverse engineer the Peppermint Tank to create advanced tech
But since Gary isn't a scientist or inventor, it'll be the human, male counterpart of another one of Ooo's royals. Perhaps Slime Princess', because of the whole Elemental thing. Or even a female version of the Duke of Nuts who Gary can't stand. The Multiverse of Adventure Time has neighbors derived from Flapjack.
It would seem odd that Flapjack's universe is exclusively within the Multiverse of Adventure Time, considering how the Multiverse works and how it appears to be an odd one out. In fact, Adventure Time is not the only series to have ties to The Marvellous Misadventures Of Flapjack. From the original team behind Flapjack include J.G. Quintel and Alex Hirsch, meaning Regular Show and Gravity Falls also owe their existence to the show. Who's not to say that all their universes are connected, with Flapjack as the linchpin? The Winter King's crown switched Ice King and Princess Bubblegum's personalities.
The Winter King didn't "push through" the curse or transfer his particular brand of madness onto the Candy Queen. Instead, he switched personalities with Princess Bubblegum. This would explain several changes to his personality and behavior, such as: him creating ice people for an ice kingdom, his sudden focus on Marceline instead of Betty, and his sociopathic tendencies. Princess Bubblegum, in turn, got the brunt of Ice King's condition.