History UnwittingInstigatorOfDoom / FanWorks

** Tyler Wittebane sending his assassins to try and kill Luz ends up escalating the CollateralDamage in Gravesfield to the point that [[spoiler:it ends up being turned into a giant crater after only 4 hours, destroying his ancestral home and killing off nearly all his people]]. Though, he considers it to be WorthIt, [[spoiler:Not knowing that Luz survived al that and is now coming for him in the Demon Realm.]].

** 24 years before the start of the story Eda discovered the Mutant Realm aka the ''My Hero Academia'' world. While there King was captured by All For One and got his hands on his Titan Blood. Even after she rescued him and returned to their home world, the supervillain acquired the means to follow her back to the Boiling Isles and waged a 10-year long war that resulted in many casualties of her people, something that haunts her to this day.
** Tyler Wittebane sending his assassins to try and kill Luz ends up escalating the CollateralDamage in Gravesfield to the point that [[spoiler:it ends up being turned into a giant crater after only 4 hours, destroying his ancestral home and killing off nearly all his people]]. Though, he considers it to be WorthIt, [[spoiler:Not knowing that Luz survived al;l that is now coming for him in the Demon Realm.]].

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* ''Webcomic/TheBikiniBottomHorror'': [[spoiler:Mr. Krabs mutilating the Tortured One to get meat for his Krabby Patties drove the Patrick clone to kill other people with Spongebob insufficiently cooking one such meal for the original Patrick on purpose to ensure the carnage happened]].

* In ''WebVideo/SwordArtOnlineAbridged'', Keita of the Black Cats of the Full Moon recruits the tutorial NPC into his guild through an undocumented exploit. [[spoiler:As Kayaba reveals in the final episode of Season 1, part of the reason thousands of players died was because they had no idea how the game played due to a missing tutorial NPC, an issue which was part of a massive crunch-caused programming oversight that Keita never got to report because he died back in episode 3; if his debt to the mafia didn't make him commit suicide, the soul-crushing guilt of causing thousands of needless newbie deaths for his own convenience definitely would have.]]

* ''FanFic/FantasyOfUtterRidiculousness'': Rumia is this during the Extra Stage. This being one of the more idiotic youkai in Gensokyo and being shrouded in darkness at the time, she didn't know enough to keep from getting near Megas, and even then she was smelling her food of choice close by. Coop and the others were completely unaware of her presence, and when Megas turns to leave the area it accidentally kicks her into the Garden of the Sun, where she collides with and snaps several sunflowers in half. This in turn [[BerserkButton infuriates]] [[TheDreaded Yuuka Kazami]], who proceeds to go on the warpath against Megas in the belief that Coop had damaged the flowers on purpose.

* [[spoiler:TCB!Lyra Heartstrings]] is revealed to be this in ''Fanfic/TheConversionBureauTheOtherSideOfTheSpectrum''. [[ForWantOfANail It turns out]] that the reason why the MirrorUniverse Equestria turned into [[TheEmpire the Solar Empire]] and is carrying out its [[AssimilationPlot ponification crusade]] against humanity is all because [[spoiler:she went on a scuba diving trip with some friends where she happened upon the sunken ship of the KV-62 Archaeological Party coming from [[WesternAnimation/MyLittlePonyTVSpecials Dream Valley]]. Unfortunately, she also found the [[ArtifactofDoom Bag of Tirek]], which seeks to carry its maker's will out by enslaving every living being in existence and targeted humanity first [[DisproportionateRetribution out of revenge]] because Tirek himself had been defeated by a human in the past]].

* A ForWantOfANail variant in ''[[https://www.fanfiction.net/s/12296999/1/If-I-Were-Me If I Were Me]]'', where Kakashi takes a different path to the memorial stone that brings him near to where Sakura was being bullied. Seeing him, Ino falsely assumes that a responsible adult is going to step in, so she doesn't intervene herself; as a result, she and Sakura don't become friends. Making matters worse, Kakashi makes a half-hearted comment to Sakura, fueled by his belief that she'll either persevere through this or quit. Sakura tragically [[TakeAThirdOption takes the third option]] of surviving by suppressing her trauma, creating a volatile SplitPersonality.

* PlayedForLaughs (kind of) in ''[[https://www.fanfiction.net/s/13311014/1/For-Want-Of-A-Knight For Want Of A Knight]]''. A pair of Altesian students trick Jaune into thinking that the female of the duo liked him, all so that they can cruelly prank him. Unknown to the pair, however, Jaune has [[CluelessChickMagnet a lot of admirers]] who signed a peace treaty of sorts regarding him, and their actions broke it, leading to Jaune's admirers officially allowed to romantically pursue him, doing over the top actions along the way.

* ''[[https://archiveofourown.org/works/34346623/chapters/85463296 Hawkmoth Gets a Reference]]'' has Nadja Chamack mention the existence of an online list of akumatized villains whose designs had to have been made on drugs in the aftermath of a battle on live television. This mention was caught by Hawkmoth, who takes the entire thing personally, does some self-reflection and inspiration searching over a hiatus, and comes back to terrorize Paris with not only more dangerous akumas, but ones whose victims have more distinct memories [[MyGodWhatHaveIDone of their actions while under his control]].

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* ''Fanfic/NoOneBreaksMyHeartLikeYou'': Barbara could tell that Mary Jane was unhappy and genuinely wanted to help her, so she talked with Mary Jane about her marriage problems. However, this talk was heard by Peter. Feeling guilty for the problems, Peter decides to end their marriage, feeling Mary Jane can't be happy with him.

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* ''Fanfic/PokemonResetBloodlines'' has a few points where the actions of heroic characters would have ramifications down the line that were far less moral than planned: Cynthia's retrieval of the Adamant Orb as a child would eventually lead to the antagonist [[spoiler: William Stronger, the Bloodliner Hunter]], while Gligarman's defeat of the criminal Heratia would later lead to the actions of her six criminal sons to go unchecked, though this would later lead to a inverted 'Unwitting Instigator of Hope' trope when the actions of the youngest of her sons fathered [[spoiler: Ash, Red, and hundreds of others]] as part of his criminal activities.

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* PlayedForLaughs in ''[[https://www.fanfiction.net/s/13280489/1/Choose-Haru-vs-Ann Choose: Haru vs Ann]]'', when Joker tries to explain his decision in [[OneTrueThreesome dating both]] [[EveryonesBabySister Futaba]] and [[TeacherStudentRomance Kawakami]], he uses an example of his classmate Mishima being unable to pick between two perfect girls (in the analogy case, Ann and Haru) just as Ren couldn't pick between just Futaba or Kawakami. This leads Ann and Haru in a competition to win Mishima's heart, which drives Ann into kissing Mishima and making him faint in shock, sending him to the hospital.

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* ''Fanfic/{{Martyshka}}'': In daring Raz to procure a file from Truman, Norma had unwittingly set Raz down a path of self-discovery and learning that he was technically kidnapped from his real family.

* ''Fanfic/LifeOreDeath'': Zigzagged. Aqualad brings his teammate Ferris to Atlantis for her birthday. There he is able to settle his inner turmoil between his homesickness and his duties to the team, meaning the Team is better able to defeat Clayface unlike in canon. However, [[spoiler:without this event, Aqualad never heads to Atlantis like he did in "Downtime", which leads to Black Manta being able to steal the entirety of Starro's frozen body. This means the Light now can produce more Starro-Tech to control more heroes outside the Justice League, including ''Ferris'' herself]].

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** The entire reason that the [[EvilMask Mask of]] [[VideoGame/KnightsOfTheOldRepublicIITheSithLords Darth Nihilus]] ended up on Remnant was because [[spoiler:a team of adventurers, wanting to keep the mask out of [[Franchise/StarWars Darth Vader's]] hands, decided to pull a SealedEvilInACan using a primitive planet in the Unknown Regions as the proverbial "Can" for Nihilus's "Evil". That planet happened to be [[WebAnimation/{{RWBY}} Remnant]] and the first person who finds the mask is a random monk. Under Nihilus's influence, the monk transforms his church into a ReligionOfEvil specializing in training deadly assassins. These assassins claim hundreds of victims during the Great War and became notorious enough for the King of Vale to send his most trusted general to eradicate them. After the cult is wiped out by Vale's army, the mask is taken as a trophy by the army's general, [[OriginalCharacter Alixandre Arc]]. Alixandre eventually realizes the mask is evil and hides the mask inside a secluded cave. This is the same cave that Alix's descendent, Jaune, wanders into on his way to Beacon, resulting in his possession by Nihilus's soul.]]

* ''Fanfic/JauneArcLordOfHunger'':
** The entire reason that the [[EvilMask Mask of]] [[VideoGame/KnightsOfTheOldRepublicIITheSithLords Darth Nihilus]] ended up on Remnant was because [[spoiler:a team of adventurers, wanting to keep the mask out of [[Franchise/StarWars Darth Vader's]] hands, decided to pull a SealedEvilInACan using a primitive planet in the Unknown Regions as the proverbial "Can" for Nihilus's "Evil". That planet happened to be [[WebAnimation/{{RWBY}} Remnant]] and the first person who finds the mask is a random monk. Under Nihilus's influence, the monk transforms his church into a ReligionOfEvil specializing in training deadly assassins. These assassins claim hundreds of victims during the Great War and became notorious enough for the King of Vale to send his most trusted general to eradicate them. After the cult is wiped out by Vale's army, the mask is taken as a trophy by the army's general, [[OriginalCharacter Alixandre Arc]]. Alixandre eventually realizes the mask is evil and hides the mask inside a secluded cave. This is the same cave that Alix's descendent, Jaune, wanders into on his way to Beacon, resulting in his possession by Nihilus's soul.]]
** The circumstances which led to Jaune finding Nihilus's mask are due to the actions of a single Beowolf that Jaune stumbles across on his way to Beacon. The Beowolf chases Jaune into a cavern where he hides out until the Grimm grows bored and leaves. This cavern was the aforementioned hiding place of Nihilus's mask, resulting in Jaune taking the mask with him to Beacon, setting the stage for Darth Nihilus's eventual return.