Because everyone seems dead-set on being entirely unimaginative when it comes to Adventure Time fanfics, I've taken the liberty of jotting down a few prompts for those of you out there not interested in copy/pasting the six or seven plotlines currently in circulation. Take them or leave them, or adapt them to your wishes, but I'll be glob-damned if I have to read yet another "Marceline moves to a new school and meets Bubblegum, but strange feelings make her want to be more than just friends" high school AU, or another "Fionna wants to resist Marshall but he's just so darn roguishly handsome!" morning-after fic.
Prompt 1: The Sorcerer
Finn lives in a world with an underground magical community, and despite her otherwise liberal view on social politics, his long-time crush PB doesn't appear to have made magic free to practice in the Candy Kingdom. What happens when Finn discovers he's got quite a bit of talent in the arcane arts? Jake's touch-and-go relationship with the law likely makes him a supporter of whatever keeps his brother alive, but how many other friends will say the same? This one brings some serious world-building potential, since so far in the show whatever magic you practice seems to be tied to the element you happen to be grown from. How does Finn being Human affect his magical ability? Is he stronger? Weaker? If you're really feeling brave, maybe take a stab at explaining how the nuclear fallout of the bombs somehow spread magic throughout Ooo.
Prompt 2: King Finn
Finn is known world-wide as a noble adventurer, and quite often claims residency in the fictional 'Grass Kingdom'. But what if, through some twist of fate, that kingdom became not-so-fictional? Maybe a few foreign dignitaries don't quite grasp that Finn's not really a king, maybe PB pushes a few deals through to get the area formally recognized, maybe Finn just decides to put all his magical artifacts to the test and conquer the place. Whatever it is, it'll make waves across Ooo.
Prompt 3: The Hunter
Seriously guys, Finn is a glob-damned MONSTER HUNTER. How are there not a thousand fanfics out there that deal with his actual day-to-day life?! And I suppose you could say that the canon show tells that story, but I would submit, in turn, that you all have royally missed the chance to turn Finn into the Witcher. Can you imagine? "Yeah Marcie, that's a Were-bear infestation you've got right there. Tell you what, get me a few potion ingredients I need, I'll get rid of them for ya." "Yeah, that Ice Giant really kicked my butt, but then I found this 'Ritual of the Forest' thing, so now I'm gonna wipe the floor with that guy." Whatever it turns out as, the life of a career adventurer in Ooo isn't gonna be nearly as sunshiny-rainbows as the show portrays it as. There will be fear. There will be turmoil. People will get hurt. It's what stories are made of.
Prompt 4: Marceline the Vampire Queen
I know it doesn't come up much, but Marcie is an actual Monarch. And yet, she does practically nothing to lead her country. This one is more of a political drama, but here are a few questions to stir your imagination: How did she become Queen? Was it through birth, or did she win it? What does Marceline actually do as Queen? Are there are a lot of Vamps/Undead she's supposed to be leading, or are there only a handful and 'Queen' is more of an honorary thing? Also for you Bubbline fans out there, I see a serious lack of "Marriage for Politics' Sake" fanfics on this site! Nearly every Bubbline fic pitches them like the only reason they aren't already a couple is because they hardly see each other; a political version with arranged marriages brings in the good ol' "I'll hate you until all that's left is mouth-to-mouth combat" plotline. Go wild!
Prompt 5: The Bodyguard
Again, Finn is a widely-respected Hero. Why wouldn't King/Queen Whatever want him to protect their precious child? Depending on which person he's assigned to protect, there are quite a few ways this could go. If he's assigned to Princess Bubblegum, he could be the carefree adventurous soul to her reserved, cognitive personality. With Marceline there's the "I'm a Vampire, why do I need a Human bodyguard?" story, which might turn out as Marcie poking fun at Finn for being a Human, and generally treating him as a servant, until her bravado leads them into a situation where Finn can prove himself, or something comes up where she actually needs to depend on him. Additionally that Marceline/Finn partnership could be made so that they get along a little too well and, with a minor character tweak on Finn's part, they just go around sassing people into submission. Flame Princess would be a really interesting story, just to see how Finn thinks his way around having to work in a volcano. This would actually pair decently with my Sorcerer prompt above, in that Finn could dive into magic to solve his heat-resistance problem, causing rifts between his friends and his duty as bodyguard if they don't like his magic use.
Prompt 6: The Last Human?
Can you believe there are zero, read it, ZERO fanfics where it turns out Finn isn't the last human in Ooo? And I'm not counting that one where Finn travels to Aaa and meets Fionna, that doesn't count. (There he's traveling to an alternate reality; I'm talking about finding humans in his own world.) Think of the species-specific questions this now raises! Is Finn just a weirdly good warrior at 13 years old, or is it something in post-apocalypse human DNA that makes them natural fighters? Are they magically inclined, or magically inept? Does any pre-apocalypse culture or science still remain, and if so what effect does it have on Ooo when it comes into the light? Where did Finn come from, and why didn't his people come find him? Alternatively, this would be a neat addition to a Hunter story, where Finn has an older, more experienced Human to mentor him in monster hunting, and teach him various survival spells, tricks, and rituals.
Anyway, those are just a few ideas I thought should've been pretty obvious considering the rich world of Adventure Time. Apologies if I seem a little condescending, it just feels like after going through page after page containing nothing but minor variations on the "Bubbline high school AU", the vanilla Bubbline fanfic, the Fio/Lee Twilight rip-off fanfic, the Finn/Marceline slavery fanfic, the Gumball/Marshall fanfic, and the rarer Finn/Marshall fanfic, someone has to stand up and say "UM, WHAT ABOUT ANYTHING ELSE?"
Again, feel free to modify and combine any/all of these, and don't be afraid to switch them over to the Land of Aaa to get a bit of gender-swapping going. Just please give me a little shout-out if you decide to use one of my prompts so I can see what you've made from them!
(I do not own Adventure Time, all characters are property of their respective owners.)