Don't mind me, just compiling a list of AUs and fanfics I've been thinking of here for my own sake, because I'm afraid I'll forget them under the stress of my current workload!
Steven Universe:
TrueQuartz!AU (Steven is the son of an actual Rose Quartz, namely Shy Rose)
CrystalTemps!AU (Featuring Lapis, Peridot, Bismuth, and Spinel as our main CGs - with Lapis and Peridot as a QP Fusion called Variscite - and a lot of role/mom-swaps abound)
StevenTale (Steven Universe x Undertale crossover; Steven Universe characters in the settings/plot of Undertale, basically)
Undertale:
SaveHim!Ending (You can't save Asriel, but maybe you can save Him. Even after all he did to you, he deserves it. But that requires your own work. Basically an exploration on concepts of AI, autonomy, the plot of all Undertale paths, and more)
GameOver!AUs (Basically hypothetical scenarios on what would happen when you lose to the major bosses of the game)
Pokemon:
NotAlone!AU (Mystery Dungeon continuity, and basically an AU where the main character of Super learns they aren't the only human-turned-Pokemon, drawing on the protagonists of the past games)
Glitchmon!AU (Rarer as they've become with each passing generation, and now basically impossible to access without outside hacking tools, we all remember glitch Pokemon, right? Well, in this world, they exist, alongside regular Pokemon!)
AshRed!AU (Universe where Ask Ketchum/Satoshi is the little brother of Red. Not much else too it, save the fact it probably falls under Pokemon Yellow/Let's Go Pikachu Versions)
Dragon Ball:
AlternateZ!AU (Basically a complete rewrite/divergence of Z from the beginning, starting with Goku reluctantly going with Raditz into space. Based on a weird dream I had, and I'm trying to expand it.)
Monster!AU (Aside from the humans, all aliens/creatures/gods/whatever in the series are based off of classical monsters!)
Bleach:
Hollow!AU (In which Ichigo and friends fail to save Rukia from her execution, and Aizen uses their grief and rage to his advantage. Alongside his original Arrancar, he now has some of the most powerful Hollows under his control.)
Elder Scrolls 5 Skyrim:
The Divine Winds of Time (A Skyrim x Rune Factory 4 crossover. Basically a little what-if where, in the attempt to save her life, the lovely Divine Dragon Ventuswill and Frey are transported to Tamriel, where they meet the Dragonborn and Paarthurnax, Odahviing, and even Akatosh's firstborn himself.)
Fullmetal Alchemist (Brotherhood/Manga Canon):
HomunculiKids!AU (The Homumculi return, but as kids, with amnesia and no powers. Placed under monitored care, they slowly regain their past memories, but their previous attrocities clash with their moralities and behaviours, leading to a ton of turmoil. Mostly fluffy domestic stuff, though.)
And I'll add more as my mind keeps brewing!
Oh hey, more ideas!
Evil Within:
Flowers!AU (In a different, better world, Reuben Victoriano is a renowned psychiatrist who revolutionized dealing with mental illness. He's dealt with disassociative teens, traumatized cops, and a slew of patients with a variety of ailments. But when he meets an eccentric artist who might be suffering from PTSD, he realizes the man before him is very familiar in ominous ways.)
Fallout 4:
Institutionalized!AU (Nora saw Nate get shot as they took Shaun away. But when she wakes up seemingly ten years later from that same cryosleep, she finds his pod across from hers, completely empty. And on the road to finding her missing family, she learns a new, terrible truth about the Institute.)
Steven Universe:
PearlSwap!AU (Kind of straight forward... ish Instead of being Rose/Pink Diamond's Son, Steven is the son of Pearl.)
Kids Next Door:
OperationAACER!AU (Ignores Operation INTERVIEWS/GKND continuity. Nigel and Sector V are contacted by another secret organized, one that is friendly towards kids and adults. And this contact will shake the very foundations of the KND and it's enemies to their cores.)
Not much this time, but these ideas have been bouncing around in my head for a while, and I wanted to add them while I still remembered!
Even more ideas!
Steven Universe:
Mom's Pets!AU (No one but a Diamond could withstand the power of another Diamond. And no powerful shield or layers of Earth could save any other Gem from that power. Basically an AU in which all the Crystal Gems except Rose/Pink Diamond became corrupted.)
Robot!AU: (Simple enough, all Gems are robots instead, and Steven is a Cyborg. The rest of the world may or may not be more cyberpunk-esque, or it may not. Don't know yet.)
Fullmetal Alchemist (Brotherhood/Manga Canon):
Steampunk!AU: (Pretty straightforward. FMA is pretty fantasy-steampunk as it is, but this time it's set in Victorian times instead of a pseudo pre/mid-WWI setting.)
Renaissance!AU: (Again straightforward. Story is set during the Renaissance age, when alchemy was very popular.)
Boku no/My Hero Academia:
Midoriya Magica (Basically a crossover of PMMM and BNHA/MHA. Follows the plot of PMMM, but features characters from MHA, and quirks replace magic.)
Hazbin Hotel:
RoleSwap!AU (Not exactly my own original idea, but rather my take on a universe where damned sinner Alastor and equally damned boyfriend Angel Dust open a hotel in hopes of redeeming the denizens of hell, but have to contend with it's princess Charlotte and her ulterior motives. Would also try to rectify the problematic aspects of the show as best I could.)
Overlord!AU (Again, not my fully original idea. Basically, the main cast - aside from Charlie - are all major Overlords of hell. Charlie still has her hotel and hopes for redemption, but this time she's aiming high in her ambitions. If she can get at least one Overlord redeemed, then surely others can follow, let alone simple sinners, right?)
And I'll keep on adding and adding, hopefully! Cheers!
Even more ideas!
Hollow Knight:
OutsideHelp!AU (fan sequel instead of Silksong. Hornet, alongside the Shade Lord - taking an altered form of Ghost - travels to a distant kingdom of Mosswood to seek help from its Root and Wyrm to rebuild their crumbling homeland.)
HollowTale!AU (Undertale... But with Hollow Knight characters/subplots/themes. Not exactly original, but I'd like a stab at my own interpretation!)
HollowRune!AU (Like HollowTale. But Deltarune instead.)
PalePrince!AU (Basically an au where the Pale King realized his attachment to the Hollow Knight meant his plan had already failed. Instead, he became the vessel/host for the Radiance/Infection, and now THK rules over the kingdom as the enigmatic Pale Prince. But not being hollow himself, the king's own bindings begin to fail. And the Pale Prince and Hallownest now wait for a savior from the ever encroaching Radiance.)
Powerpuff Girls:
PowerpuffSquad!AU (Not really an AU so much as a future sequel. Now teens, our heroes continue to protect a more modern Townsville, while battling raging hormones and stressful academics. And one of the group realizes something that changes their entire dynamic forever.)
She-Ra:
Purified!AU (A bad ending/au where Horde Prime won. And now, everything is not perfect, in his Light.)
HordeDaughter!AU (Where Hordak directly raised Adora, and how it changes many dynamics of the series.)
Steven Universe:
Demayo!AU (Greg wasn't so forgiving after Three Gems and a Baby. For Steven's protection, he was sent to live with his grandparents. And aside from his weird gem, he's been living life as a normal human boy. Until puberty sets in, and suddenly his gem starts glowing, and he's able to levitate, and he suddenly has a pet lion. Until 3 strange ladies appear on their doorstep, on his 13th birthday.)
SecretsOut!AU (When Rose gave birth to Steven, is everyone immediately noticed that something was... Clearly off, about his gem. Basically, Steven's gem was rotated during birth - not sure if purposefully or not yet - and Rose is outed as Pink Diamond, and how it affects Steven and everyone else going forward.)
And I'll keep adding more and more!
Here we go again!
Steven Universe:
BigBrother!AU (Even from birth, even with our beloved Garnet, his destiny was never written in stone, always elusive from any future vision. No one even knew if he'd be a Steven, or a Nora. And he'd assumed that had just been another quirk from being a Human-Gem hybrid. But what if there was a secret, grim reason behind his uncertain futures?)
DeltaRuniverse!AU (Basically, Steven Universe meets DeltaRune.)
The Promised Neverland:
ThePromisedUniverse!AU (It's the Promised Neverland, but Gems are the Demons. Some characters would have to be humanized for things to make sense -- probably the Crystal Gems and crew -- but... Yeah!)
ThePriceofSurvival!AU (Norman? Shipped to Lambda. Not that Emma knows. Ray? Shipped to Goldy Pond. Not that Emma knows. And Emma herself? Training to become a Mother.)
PaymentforPromises!AU (*Unintelligible* was always unpredictable with its costs and promises. They're all safe on the Human Earth, now. But the Earth is not safe from them. With no easy way back to the Demon side, and Musica's blessed blood, everyone must contend with their growing hungers... And deteriorating minds.)
Resident Evil 7: Biohazard
AllInTheFamily!AU (Chris Redfield is tasked with tracking down and ending bioweapons and shady organizations, to prevent another Raccoon City incident. But one day, an anonymous tip sends him and his team into the heart of the Louisiana bayou, where they'll have to contend with aworst-case scenario. An entire community has succumbed to a terrifying new infection, and at the very center of this hellscape is a big, dysfunctional family, with many dark secrets.)
Hollow Knight:
GodSwap!AU (Basically, all the major deities of the game are flipped around. Journey through the decaying kingdom of Hallownest, the once mystical home of the Shade King, now plagued by a terrifying infection, spread through Nightmares.)
KingdomSwap!AU (Sort of a different GodSwap universe. Hallownest is the Kingdom of the Radiance, a land of Dreams... Now decaying under a plague of Light.)
Dragon Ball:
SuperGT (A what-if scenario where the plots of GT and Super intersected. Gods of Destruction and a Multiverse, alongside Black Star Dragonballs and evil Tuffles? Sure!)
EternalEmperor!AU (What if Frieza hadn't enslaved just the Saiyans, or hadn't enslaved them first? What if the galactic tyrant had discovered the Namekians beforehand? Certainly, the evil overlord could make use of their unique combat skills, their healers, and if nothing else, certainly their immortality-granting Dragon Balls.)
Let's go again! Let's go again!
Elder Scrolls V Skyrim:
Mortality!AU: Upon the Dragonborn fulfilling the prophecy and beating Alduin, he and the dragons of Skyrim all undergo the judgement of the Divines. Said judgement? Stripped of their draconic forms, they must now learn what it means to be mortal, as the Dragonborn has done.
Dragon(born)Priest!AU: In which Alduin returns earlier than canon, and finds his fated nemesis as a wee babe. But perhaps if raised and indoctrinated from infancy, perhaps they won't be his enemy after all. Perhaps, instead, they will be his most loyal priest, without worry of betrayal.
Fallout 4:
GhoulandSynths!AU: In which Nate was on duty and ghoulified during the Great War. And Nora got into the Vault with baby Shaun, only to wake up alone, with a shoddy memory and some newfound abilities.
Soul Eater:
MagicShibusen!AU: Post-anime canon (not adherent to manga). Even with the Kishin defeated, his effects still ripple across the world. One such is a new wave of magic users. With a tenative peace between Witches and Death, the DWMA takes on a few exchange students of magical proportions.
Hollow Knight:
HollowRain!AU: In which the Void Sea does not free the Slugcat like it believes it would. Instead of finding its old family, the Slugcat becomes a part of a new one. Rain World x Hollow Knight crossover!
Dragon Ball:
Reborn!AU: Waaaay post canon. Follow the adventures of the Z Warriors' descendants as new evils threaten the world and multiverse! Basically my OC shenanigans.
Alien Franchise:
Abominations!AU: Ripley 8 discovers she wasn't the only one of her family that Weyland-Yutani decided to do scientifically experiment on. Amanda Ripley awakens centuries after her natural death, and awakens realizing she's changed into something that's haunted her nightmares.
Unitology!AU: Dead Space meets Aliens! Idk how, but just imagine the abomination that's a Xeno-Necromorph. Now imagine how Weyland-Yutani/the Church of Unitology would f*ck things up. Can you see it yet? Have fun and try not to die!
Steven Universe:
AlternateFuture!AU: Basically my fix-it au. Because while a season dedicated to tackling mental health was good rep, it came at the cost of shitty story telling and so many plot holes. So, some slight changes to the store will come!
I'm on my bullshit again y'all.
Hollow Knight:
EmbracetheLight!AU: Ghost arrives to Hallownest a little later than canon... And finds a kingdom much, much different from the one we knight. And the Radiance? She's having a grand old time, back in her proper place as the rightful ruler.
NightmareKingdom!AU: In which summoning the Nightmare Heart has more of an effect than the Ritual. The Nightmare King seeks to settle down in his homeland, and reclaim all of Hallownest for himself. And with its uninfected inhabitants slowly falling under his own thrall, he may very well succeed.
Dragon Ball:
KidPiccolo!AU: Canonically, our favorite green man is only four years older than Gohan, and doesn't look it because magic woo woo reasons. In this AU, there's no woo woo magic. We got a little green bean who woke up and chose violence.
DadPiccolo!AU: Give Piccolo a kid. Give Piccolo A Kid. GIVE PICCOLO A KID.
Steven Universe:
NoOneCanKnow!AU: Because no one, and I mean NO ONE, can know Rose's dark secret. An AU where not even our dear Pearl knows the truth of her deceased lover.
UniverseBound!AU: A Steven Universe and Earthbound/Mother 2 crossover! Shenanigans and heartfelt moments abound!
Helluva Boss/Hazbin Hotel:
Apostate!AU: In which there's a special punishment placed upon nonbelievers. A punishment which will challenge Charlie's thoughts on Heaven and redemption. Very self -indulgent and OC centric
HeavenSent!AU: In which Princess of Heaven Charlie descends to Hell in the hopes of proving daddy Michael and grandpa God wrong about redemption. But failure comes with the ultimate price: Falling. And her dear uncle Lucifer seems quite eager to expedite her failure.
Jurassic World:
PerfectPark!AU: In which the Indominus escape never happens, and the park soon plans to showcase its new hybrid attraction. But when a mysterious illness delays her public debut, it also brings about some ominous, unethical implications.
CloneCornucopia!AU: If the latest movies showed anything, cloning wasn't just kept to dinosaurs. But what if it was explored sooner in the world? And much more open to the public. From the Mastodon to the Moa Bird, extinct species are being revived all around the world. But in solving the extinction crisis, has humanity created another? And where does a theme park for dinosaurs truly fit, in such a world?
Elder Scrolls V Skyrim:
Dovahkid!AU: A world where almost everything is the same... Except the Dragonborn is a child. Cause who doesn't love heaping stressful destinies and the fate of the world onto the shoulders of the youth, amirite?
Rain World:
PortalWorld!AU: Crossover between Portal and Rain World. Poor little slugcat-Chell is a test subject for the psychopathic AI Five Pebbles many portal-based experiments. Until one day a defective little core known as Looks to the Moon tries to help them escape.
Rotten!AU: In which Five Pebbles' fateful experiment fails... but also doesn't. The Rot isn't what they wanted, isn't what they expected, but... it is the Triple Affirmative he's been looking for; everything the living tumors touch, everything they consume, does not come back. But as much as he's been searching for this for himself, he has a duty to fulfill, as an iterator--he will give this gift to all of existence, whether it wants it or not.
Ah shit. Here we go again.
Hollow Knight:
HollowMonsters/PocketKnight!AU: The story of Hollow Knight... But with Pokemon! (Not all bug types, alas, because too many characters and not enough bug type)
Acolyte!AU: In which the Pale King seeks out not a Vessel to contain the Radiance, but a Vessel for her to mold into a perfect follower, to rekindle her believers and end the Infection . But things still aren't simple in this happier path. Because this promised-empty Vessel under the Radiance's wings isn't empty at all, and something more than belief may be brewing inside their mind, and that of the Moth goddess.
Daliance!AU: In which the Pale King is inspired by his bargain with Herrah. He offers to sire a child with the Radiance, one whose very existence would assure her return to Hallownest's minds, tied through him. She takes it, and now he's left with a problem: a Hollow Knight without purpose, and the weight of countless filicide on his back.
ButWaitTheresMore!AU: In which the Pale King realizes that using babies crawling out of a death pit is a terrible criteria for determining hollowness. The Pale King takes all the Vessels from the Abyss, training them all as automatons until they begin to show personhood. One by one, the candidates for the Hollow Knight are eliminated by love and care, until only one remains. The perfect, Pure Vessel to contain the Radiance.
ButWaitTheresMore-PalePrinces!AU: Variance of But Wait There's More that slightly crosses with my Pale Prince AU. In which the Pale King takes all the Vessels from the Abyss, planning on a process of elimination to determine which will be the Hollow Knight. Only problem is, he gets attached to them all, even the supposed Pure Vessel. So he takes their place and leaves the kingdom to his many children. Surely, no problems will arise from this.
ButWaitTheresMore-PalePrinces2!AU: Another variance of But Wait There's More and the Pale Prince AUs. In which the Pale King never concocts the Hollow Knight plan, immediately jumping to contain the Radiance himself. But he can't leave the kingdom without a ruler. So he leaves it to his children. This time, Hallownest is in the hands of hundreds of pure Root-and-Wyrmlings, no Void attached. Nothing can go wrong here, no siree.
ButWaitTheresMore-Daliance!AU: Variance of But Wait There's More AU crossing with the Daliance AU. The Pale King's methods for determining the Hollow Knight differ, but the bargain made to the Radiance stays the same. And now, he has to deal with fathering countless vessels, a half-spider, and a half-moth-god in the aftermath.
ButWaitTheresMore-ChildSoldiers!AU: Variance of But Wait There's More AU. In which the Pale King realizes, why just contain the Radiance when he can throw all the Void at her via his kids, whom he can raise into perfect, moth-murdering machines? Will this be successful? Probably. Will there be any repercussions to this? Also probably.
Rain World:
RainMonsters/PocketWorld!AU: Rain World, but with Pokemon. Such creative. Much wow.
HelpI'veTurnedIntoASlugcat!AU: When Moon first collapses, something goes horribly wrong... Or horribly right, from a certain perspective. The blue iterator wakes up after her collapse, far from her Can. Except she's not an iterator anymore. Is this the answer to the Great Problem? Or is this a just a new, cursed life that she still can't escape?
Owl House:
EmperorWittebane!AU: In which Caleb survives Phillip's attempt on his life... At the cost of his brother's. A world in which Caleb Wittebane ascends to become Emperor of the Boiling Isles, desperate to bring his baby brother back. Even if it drives him to monstrous means. Even if it means dabbling in the creation of Grimwalkers.
Steven Universe:
Revolution!AU: In which the Diamonds never see reason, because if Pink Diamond couldn't change their minds, then her son isn't going to do any better. Trapped on Homeworld and looking for a way home and to heal the corrupted Gems, Steven has to seek out a new way to solve his problems. But the truth of Pink Diamond's rebellion has lit a spark within the core of Gemkind, one that will grow into an inferno far beyond the banner of Rose Quartz could ever span.
Undertale:
Multiplayer!AU: Choose your character! Choose your drive, and play with friends! Will you explore the Underground, spurred on by Patience? Bravery? Integrity? Perseverance, Kindness, or Justice? Or will you be driven by sheer DETERMINATION?
DeltaRune:
LittleBeast!AU: A reversed world, where Kris is the only monster in a realm of humans. Essentially the DeltaRune equivalent of the Undertale Monsterswap AU. (Idk how original this AU actually is or not...)
DarkChild!AU: In which Kris was raised in the world of the Darkeners. Sent to conquer the world of the Light, long claimed by the monsters, will they be willing to follow through? Or will they bring peace and balance to the Light and Dark?
More au nonsense for all you lovelies!
Bendy and the Ink Machine/Dark Revival:
AudreyAngel!AU: In which our heroine is born into the ink world not as herself, but as a variation of the feminine deuteragonist of a certain cartoon. After all, every demon needs their angel, and it's time the Ink Demon met his.
DemonAudrey!AU: In which Audrey's rebirth frees the Ink Demon from his cute prison... Sort of. Now Audrey awakens as the famous cartoon, but she still has a link to this world's monster. And he wants her.
FallenAngel!AU: Role-swap AU. Bendy Stein is thrust into the hellish world of his father's inky creations, featuring twisted versions of cartoon characters Fallen Angel Audrey, Sammy Seraphim, Ghost Girl Carly, and so many more. Will he survive, and discover the secrets at the center of this world? Or will he succumb to the dark puddles?
Resident Evil:
Mamma'sMission!AU: In which Miranda kidnaps and impersonates Ethan. Now, Mia must rescue her daughter from the twisted cult leader, and uncover her husband's fate. Essentially, what-if of Village, but we play as Mia.
FifthLord!AU: In which Miranda wants to add the Winters family to her cavalcade of monstrous houses, at a steep price. The mold that runs in Ethan's veins has a dark past, after all, and a darker secret that ties him and his family to this twisted village.
Rain World:
HelpIveTurnedIntoASlugcat2!AU: Shortly post-Rivulet's campaign. In which Five Pebbles can only wait until his Rot consumes him, or he collapses, whichever happens first. But what happens when a creature outside the cycle is thrust into it, when its species cannot reproduce? Apparently gets reborn as the nearest sapient species, which has been karmically harassing him since his whole mess started. Fate has never been particularly kind to Pebbles, after all.
FNAF:
GenericMikeGotStuffedInASuit#Whatever!AU: Pretty self-explanatory. Because animatronics and the Afton fam have never meshed well together.
GlamrockMike!AU: Nothing too special, just a little au where Glamrock Freddy is different because he's the only animatronic... With a soul. Michael Afton's soul, because fate is a cruel mistress to the guy who wanted to right his family's wrongs.
Steven Universe:
BlackDiamond!AU: After the series, a long-lost, powerful gems reawakens and returns to the universe. Far stronger than all of gem-kind combined, and extremely enigmatic in motive and drive. But her prolonged absence was for dark reasons, and her return marks a new threat that Steven, his friends, and his family may not walk away from.
ShatteredCrystals!AU: Between the Gem War and modern times, Rose decided to reveal the truth about Pink Diamond... And it broke the weak foundations of the remaining Crystal Gems apart. Garnet unfused, and Ruby and Sapphire left the temple. Amethyst was never found in her Kindergarten. Now, it's just Pearl, taking care of a little Steven with Greg. But the past has a way of still haunting the present.
