A Song of Ice and Fire
- In Wearing Robert's Crown Drakebert has the Wall heavily reinforced. And then the Others bring it down in one night, killing most of the defenders who they can raise to reinforce their army.
- In Animorphs Redux, this potentially applies to the team, as they have reset reality and risk the Yeerks winning all over again, but most specifically for Ax in The Extreme, as his actions create a Z-Space rift that will make it even harder for the Andalites to reach Earth while trapping a vast Yeerk fleet above Earth, all in the name of rescuing one other Andalite from becoming a host, with no evidence that this effort worked.
- In Wrong Road to the Right Place, Laurel's attempt to find out who is behind the List led to Moira being forced to agree to having a contract put on Laurel's life in the belief that this would draw attention away from her own children.
Avatar: The Last Airbender
- "Lee" and Smellerbee force Jet into therapy in The Stalking Zuko Series in hopes of curing his obsession with "Lee". Getting therapy ends up helping Jet realize that "Lee" is probably not a firebender...But his uncle Mushi is since Mushi is constantly making gallons of tea without firewood and goes naked in their poorly insulated apartment in the middle of early spring.
- The Northern Water Tribe in Reluctant Hero outright abducts the new Avatar when he's found on a Fire Nation ship, forces him to assimilate while he's obviously struggling with his status and the expectations coming with it, and considers to wipe his memory clean in order to make him a better student dedicated to save the world. The teen ends up freaking out and running away.
- Riding the Dragon has Cecilia Kurita oppose her brother's coup only to leave herself in the position where she has no choice to claim the throne she never wanted in the first place, since anyone else who took the throne would have to kill her as a rival.
- In A Boy and His Dog, Komamaru stop Uryu from the using the Hollow Bait by biting his leg, with Kon catching it when he lets go. However, after Ichigo gives a speech of how while he's not afraid to take on the Quincy's challenge, he won't do it in Karakura Town where it'll put his sisters in danger, Kon then claps in applause... while still holding the Hollow Bait.
Buffy the Vampire Slayer
- Chosen To Destroy, written as a Take That! at Buffy the Vampire Slayer and Angel, which has the First Evil show up after the Season 7 Buffy finale, basically to gloat over how it's going to open all the world's Hellmouths and kill all the Slayers in the world, and to rub it in that it's all Buffy's fault - while some of it was the First's manipulations, it makes it very clear that the main reason it's going to win now is because of Buffy's ego and stupidity (and Angel's to a lesser extent).
- In Taaroko's Buffy the Vampire Slayer, Buffy has a moment of panic when she convinces herself that the army of undead Slayers is a side-effect of the spell that activated all living Potential Slayers, but Giles and Willow convince her thats impossible due to the nature of the magic used being too pure to have such a terrible consequence.
- A more serious example occurs in Season 9; after the gang interrupted a ritual intended to summon an Old One, they only learn later on that they interrupted the ritual at a point after it would wake the Old One but before the casters could identify which Old One should be awoken, with the result that every Old One trapped in the Deeper Well is unleashed on the world.
- Willow in Xendra reveals that the Watcher's Council is bound by a magical contract. One of the penalty clauses of said contract kills all descendants of the party that breaks it which, as Quentin Travers points out, would cover somewhere around 80% of Western Europe and 50% each of Eastern Europe and North America. Only the fact Willow is considered a third party keeps her from being responsible for the deaths of hundreds of millions, including potentially wiping out the Slayer line forever.
- A Letter to Riley features Buffy telling Wesley, Cordy and Gunn that they almost let Angel destroy himself during Darla's return without ever considering that the reason for his obsession with Darla was that he was under a spell making him excessively fixated on her. As Buffy points out, Giles worked out that Angel was under a spell after talking with him for a few minutes when he hasn't even seen Angel for over a year, and yet Angel's own team never realised that was even a possibility until after Darla has been killed by Buffy and Angel.
Calvin and Hobbes
- In Flashforward opens with Kate Beckett (towards the end of Season Four) finding a time portal that lets her switch places with her past self early-Season One, and she immediately decides to use this opportunity to find the evidence that will identify her mothers killer based on her future knowledge. However, her impulsive act results in her being killed in the past (which also erases her past self in the future), creating a timeline where America and China are on the brink of war after the events of Linchpin unfolded differently in the absence of Castle and Beckett (to say nothing of Bracken making a presidential campaign out of the resulting fear), requiring another time-traveller to recruit the Castle of the new timeline to go back and help prevent Becketts death.
- In Massive Multiplayer Crossover-but-mostly-Rurouni Kenshin story Blood and Revolution, Saitou and Shun awaken the Earthkami to stop a lesser kami from going to war against humanity with an army of youkai. It turns out that waking up the incarnation of the earth itself is not a good plan. They manage not to literally end the world, but it does cause the end of civilization.
- In Kage, a crossover story between Jackie Chan Adventures and W.I.T.C.H., the Guardians are quick to attack Jade when she first arrives in Meridian, thinking her to be a minion of Prince Phobos. That, combined with Elyon losing control and nearly killing Jade, and Caleb secretly countermanding his queen's orders to heal Jade's wounds and practically ordering her to be locked up immediately, is a major part of the reason Jade ends up joining the Knights of Vengeance, beginning the prophecy that dictates that she will cause the fall of Kandrakar.
- The events of the three-part finale for Children of Time are largely due thanks to Sherlock Holmes, Dr. Watson, and teenage Beth Lestrade. The friendship between Holmes and Watson has been disintegrating, and the argument that they have early on tears a huge rift in their relationship — right as one of Holmes's canonical, Fixed-Point-in-Time cases is beginning. One which Watson ought to be witnessing. The case goes wrong thanks to Watson not being there and Holmes refusing to accept help from Beth. To top it off, when Holmes is kidnapped, Beth follows and is caught, herself, allowing the Big Bad to realize that she is now a Temporal Paradox that ought to be eliminated. Time Stands Still, and Beth eventually dies.
- Arguably applies, albeit to a minor degree in The Wisdom Seeker, the sequel to The Secret Keeper; after Voldemorts death, his remaining loyal followers commit various assaults to try and re-establish the Death Eaters, as they were so certain of Voldemorts victory that they made their allegiance to him too public for any of them to claim that they were Imperiused like before, particularly in the face of Kingsley Shacklebolts planned reforms. However, while dangerous, the Death Eaters lack a clear leader after Voldemorts death, and so their attacks are limited compared to what they did under Voldemorts leadership.
- In Connecting the Dots, when Kakashi teleports himself to the DC Animated Universe to try and rescue Naruto and the Konoha 11, he appears right in front of Lex Luthor. This is particularly bad as the Sharingan was the last thing Luthor needed to complete the Anti-Life Equation.
- In Fractured, a Mass Effect/Star Wars/Borderlands crossover and its sequel, this happens frequently.
- The Trans-Galactic Republic tries to "save" their neighbors from the Reapers with their powerful starships...and inadvertently stokes interspecies tensions, denies the Magnetic Hero known in canon to have pulled the feuding galaxy together, and puts their heads in the sand when the Tyrant Takes the Helm despite having the ability to put a stop to it through their superior firepower.
- The Vault Hunters clear out a Hyperion spaceport with a huge, Siren-powered rocket launcher...except the detonation also destroys their only way offworld (until Lilith decides to use her powers).
- In Origins, Samantha Shepard needs to hack a terminal, but sends Legion (her best hacker) away to solve another problem of tailing a thief before realizing how stupid this decision ends up being. She then proceeds to almost get sniped until Garrus saves the day.
- For a given definition, Aria manages to seize enough power to keep her station by hijacking Trans-Galactic Republic ships...except now those ships aren't used properly and the Alien Invasion gets out of hand when their original commanders would have just blown it all up.
- Samantha Shepard thinks she can help Cortana with a different computer system, but all this does is start playing AI Is A Crap Shoot straight. Subverted later in that it actually ends up helping in the long run.
- On a much larger scale, the Neglectful Precursors who thought their convoluted plans would keep the universe from imploding or being overrun by an Alien Invasion they'd fought off eons ago. Instead, they blunder right into this trope by influencing, if not directly causing, the things they worried about (rampaging lifeforms, alien invasions, wars among the lesser races, abuse of Psychic Powers). All because of a religious spat...
- Tends to be a habit with Naiki Satomi from Divine Blood. Some specifics:
- Underestimates the Karate Club guys and gets in a position where she has to use a chi burst to defeat them in public, while Gauron is spying on Kaname nearby.
- Naiki's fear of flying combined with a terrorist takeover of the plane she's on causes her to go on a fear-crazed berserk as soon as the plane lands, which leaves her captured and used as a hostage to insure Deimosu's surrender.
- Goes back to help Kurz's fight against the Venom Chodarl, splitting the escape party and causing Eija, Kaname, Deimosu and Sousuke to hesitate long enough figuring out where she went for the Musk to attack and force Eija, Kaname and Sousuke to miss the escape.
- Tries and fails to rescue and protect Tessa from the Behemoth terrorists.
- Uses a black magic spell that causes her to touch Tessa's soul, starting the mind merge process and also indebting her to a Demon that makes Mara queasy. Twice.
- In backstory, Naiki's intense fear of flying is due to an... interesting 10 meter trip through a hangar that occurred when she tried to operate a helicopter as a young girl.
- In the fight against the Behemoth, uses her summoned tentacles to throw Mao into a pile of debris, almost effectively taking her out of the fight.
- In the Martial Arts Takeout Race, loses control of her newly made Torrent of Debris spell.
- Before getting one of Persephone's peaches, she spends a lot of the fight against Poseidon being rescued by the older, human martial artists.
- Niamy of Fuck The Jesus Beam decides to deal with the Bombignat threat by releasing O.B.A.M.A. from his prison, despite him having started 95 World Wars as president and, as it is later revealed, being the source of the Bombignats. Upon his release, O.B.A.M.A. says that he will reclaim his domain, and takes control of the Bombignats.
- While not much of a hero, Vash of Christian Humber Reloadednote kills a dragon named Le-Hung Doe as part of atoning for killing another dragon, but learns that by killing him, he has started a Ying-Yang War, in which he must fight demons without weapons.
- The Prayer Warriors have killed many people in their fights against the Greek Gods, Hogwarts and Communist Russia, but it's implied in The Titans Strike Back that their infiltration and destruction of Hogwarts resulted in many Christian deaths, and now that the school has been re-established, they're going to deal with it differently this time.
- The God Empress of Ponykind: Celestia kills King Sombra. This allows him to ascend and become a Daemon Prince and pull the Crystal Kingdom into the Warp.
- Horseshoes and Hand Grenades: Ryusei's attempts to save his friend from the coma by killing Gentaro only made Ophiuchus resurrect Gentaro as a Serpent-bearer with a vengeance to kill his former friends. Moreover, Jiro died anyway, and was resurrected by Gentaro to serve him and kill Ryusei. And that's not talking about how this derailed Gamou's plots for the Day of Awakening and how his benefactor Tachibana—Virgo Zodiarts—has to start injecting Cosmic energy into innocent kids to make up for everything. Was killing Gentaro worth all of this in the end, Ryusei?
- In The Swarm of War, after the Kingdom learns about the Zerg and misidentifies them as a Chaos corruption, a decision is made to bring out the hidden superweapon: hibernating Space Marines. Unfortunately, nine of them are corrupted by Chaos.
- In The Boy with the Magic Notebook, Maxwell tries to summon a healing rainstorm to heal people after Shatterbird's attack on Brockton Bay. But while it did heal all their wounds, it still left the glass pieces inside them.
- In End of the Line, Sailor Moon created a magic barrier to protect her hometown from an apocalypse. As Xander furiously explains to her and Luna before he kills them, that very barrier is what caused the apocalypse by pulling magic out of everything in the world.
- In Origin Story, Sentry is actually winning in his first fight with Alex Harris. That is, until he decides to fire a bolt of energy made of "the power of a million exploding suns" at her. As a Kryptonian, Alex absorbs and metabolizes sunlight to make her stronger, more invulnerable, and heal faster. Oops.
- In Opening Dangerous Gates, the party travels to a town and finds a forcefield blocking their path. They destroy it and continue on their way. When they arrive, they find the town burned to the ground. Some demons thank them for getting rid of the forcefield that was stopping them from reaching the town.
- In One Foot Another Multiverse SI Poe does this a lot. Most of his actions tend to be less 'helpful' and more 'why would you do that?!' in nature. Heck, he does it at least once per world. One of the biggest examples is when he accidentally gives Father the formula to nuclear fission while trying to pass the written portion of the State Alchemist exam because he forgot that Amestris is at around World War I levels of tech.
- Avenger of Steel:
- Clark indirectly delivers a speech about this to SHIELD and the World Council (delivered to Fury by proxy via Natasha) as their work on the Tesseract is what drew the Chitauri and Zod to Earth.
- Potentially applies to the Ancient One; her use of the Time Stone has attracted the attention of Mr Mxyzptlk, but compared to the threat of a mind-controlled Superman, the aforementioned imp isnt quite as dangerous.
- In Harry Potter and the Mystic Force, the Hogwarts staff and students all drive Harry away despite needing him to face Voldemort. Subverted/Justified as it turns out most of the key figures were subtly brainwashed by the real Big Bad to get Harry out of the way while he carried out his own plans.
- In I Still Haven't Found What I'm Looking For, Harry Potter utilizes magic on a massive scale not seen in millennia to defeat an invading Separatist army and in doing so causes all Force users to become magic users. While the first demonstration of this is a trainee accidentally apparating instead of using a Force Jump, it quickly becomes apparent that Palpatine is far more powerful now as well and is quickly learning what he can do with his new powers.
- In A Man of Iron, Jon sparing the Moutain That Rides seems to be an uber-bad idea, even more after he abducts Pepper to lure the Iron Man out, yet it's subverted with Tony pointing Tywin Lannister would have been upset about his attack dog's death and made Iron Pointe another Castamere in retaliation.
- As in canon, Ned offers Cersei the possibility to flee with her children, which leads him to be imprisoned and sentenced to death. The Iron Man manages to save him, but Ned's eldest daughter is killed right before him.
- Fantasy of Utter Ridiculousness:
- Destruction visited upon the Forest of Magic? Marisa injured and trapped in her own house beneath a junk pile? The giant fairies, and the subsequent showdown with Suika? Yukari, who could've prevented it all at the outset, getting decked into unconsciousness by accident when Megas first arrives? Just another day in the life of Coop.
- The Lunarians didn't have any real idea what the Glorft were planning and were mostly hiding from them. The problem is that if Megas (and her crew) hadn't been there, they probably would have stayed hidden until the Glorft would have gone away... meaning that the Lunarians would have been killed and the Earth destroyed when Warmaster Gorrath smashed the moon into the planet. After overhearing Megas's crew on their return visit, the Watatsuki sisters give this realization to themselves and resolve to be more decisive next time, vowing to annihilate the Glorft should they cross paths again.
- The story takes a closer look at the worldwide weather disasters caused by the destruction of the Glorft's moon base in the source material. Gensokyo is not spared the wrath of nature, and chaos and destruction are just about everywhere. The Human Village received substantial damage, and youkai elsewhere were rendered homeless. Even in places that survived with minimal to no damage, such as the Hakurei Shrine, Eientei and the Scarlet Devil Mansion, morale is less than optimal: as an example, Hong Meiling took up her post inside the Mansion when the weather became too much to take, and no one blamed her in the least for it.* It isn't until the moon gets steadily pieced back together that life starts to return to normal... and then Megas arrives.
- Infinity Crisis:
- Loki mentions what he has heard of the Legends screw-ups in dealing with time travel.
- For a given value of 'hero', anyway; the final chapter sees ex-General Ross offer Zemo leadership of his planned Thunderbolts to act against the Avengers if it is required in future.
- Can be argued for Superman, as putting Thanos into the Phantom Zone gives the Titan a chance to forge an alliance with Zod and Darkseid to become more dangerous than ever.
- In Of Kryptonians and Queens, Merlin is called out on the fact that he chose to unleash Etrigan to stop one of Morgana's plans, which led to an innocent man being bonded to a demon for the rest of eternity (his role in Morgana's fall from grace is also mentioned, but Kara acknowledges that nobody can be sure how much of an impact his lies may have had on her actions).
- In In Hand and Foot, the Turtles and the Defenders unwittingly interrupt just as the Hand and the Foot were about to start fighting each other, with the result that the two sides turn their attention to the heroes; Michaelangelo acknowledges that, with hindsight, they could have handled this situation better.
- The Many Dates of Danny Fenton
- In TMDDF: Danny and Kara, in chapter 20 Spectra appear in Sam room, when Sam try to get wrist ray or Fenton thermos, she remember that Jazz confiscated all her weapons allowing Spectra to capture her. Later it was revealed that Jazz took Sam weapons on the behalf of Danny because he did not trust Sam anymore. Danny was horrified to learn that his actions cause Sam to be capture, but she forgives him and admits that he had a good reason not to trust her.
- In TMDDF: After Many Dates: Danny and Gwen, Sam went to Bellwood with Tucker to spy on Gwen, and when they found out about her powers, Sam used her phone to video Gwen using them since she assumed that Danny doesn't know about them yet. That was when Operative K and Operative O of The Guys in White recognize Sam and Tucker and capture them. While they escape, Sam accidentally left her phone behind and the Guys in White found the video with Gwen using her powers. So thanks to Sam, The Guys in White are now hunting Ben, Gwen, and Kevin in Bellwood along with Danny.
- In Power and Honor, a He-Man and the Masters of the Universe (2002)/She-Ra and the Princesses of Power crossover, Adora transforms into She-Ra in front of the Evil Warriors after Skeletor tricks her into thinking he's a good guy, causing Skeletor to realize He-Man is likely the result of a similar transformation with Prince Adam being the only viable suspect for his true identity.
- In Point Me at the Skyrim, Victoria dropping off two wagons worth of injured Imperial Soldiers in Whiterun to be healed was certainly heroic. It might also could be used as a Pretext for War.
- Demon's Curse: After the fiasco at the Tower of Heaven, a (heated and emotional) argument is had where Erza calls out Naruto on not telling the guild he can use part of Zeref's magic. Naruto retorts he NEVER wanted the power to begin with and that he has personal experience informing his decision to keep it secret but eventually Naruto leaves, emotionally dejected, saying that once it gets out, the guild won't treat him the same and he's going home. Later when Erza tells Mirajane about this, Mirajane panics and sets off to find Naruto. Mirajane explains that Naruto had a past case of Power Incontinence and was about to be executed until Makarov and Mirajane negotiated it down to exiled parole on the condition that Naruto stays under Mirajane's supervision and that he can never return to his village on threat of imprisonment or death. A horrified Erza suddenly realizes she might have pushed Naruto to commit Suicide by Cop.
- Superwomen of Eva: Legacies: True Blue: The first time she meets him, Hikari accidentally destroys Ted Kord's latest invention, which was not really described but potentially world changing. He takes it extremely well, though.
- Warning Letter: The Phantom Thieves are able to steal Light Yagami's heart before he can kill Raye Penber, but Light's sudden change in demeanor, coupled with a sudden cessation of criminals dying, causes his father and L to suspect Light is Kira much faster than in canon. This in turn causes L to turn his attention to hunting Phantom Thieves instead, quickly and correctly deducing that they stole Kira's heart.
- In Blessed with a Hero's Heart, Kyouya and Aqua could have not only purified a Lich, but also gain its treasure, if they had only bothered to be a bit more patient. Instead, Kyouya attacked him before the Lich could speak and destroyed an object that was personally important to him, Aqua made a slapdash seal that completely screwed with the place, and then ran away when they were attacked. Had it not been for Izuku finding a way to help the Lich recover that object and erasing the seal, Axel would have been in really deep shit.
- Daughter of Fire and Steel: Overwhelmed by Krypton's destruction, the guard of the prison ship carrying Zod and his followers decides to release them so they suffer a slow death by starvation while he takes his own life. Instead of fighting among themselves, the prisoners use their smarts to engineer the Phantom Drive into a hyperdrive to scavenge for supplies and survive.
- In Shazam fanfiction Here There Be Monsters, the Squadron of Justice have just arrived in Venus when Bulletman is attacked by a frog-like monster. Bulletman flies skywards followed by his wife to get rid of the amphibian, with the unfortunate consequence of alerting the Monster Society of the Squadron's presence.
Demon King Daimao
- Happens quite often in the Doctor Who fancomics on Rich's ComixBlog.
- In The 10 Doctors, the entire reason the Time Lords lost the Time War is that the Valeyard — who the Time Lords created in the first place — killed Damon before he could give the Daleks' attack strategies to the Eighth Doctor. If this hadn't happened, the war would have been much less destructive, the Time Lords and Gallifrey would still be around, and the events of The End of Time would never have happened. Essentially, it's the Time Lords' own fault they got into the Time War, which isn't too surprising.
- Later, the Tenth Doctor finds the relevant data spool. He reluctantly decides against giving it to the Eighth Doctor, in order to keep history on track.
- In Outrage, the Sixth Doctor reveals Jem's secret identity to Rio Pacheco. Rio doesn't take it well.
- In Seeds of Destruction, the Fifth Doctor lands on a lush garden planet, ignoring Peri's request of Pasadena, California. Said planet turns out to be the deadly planet Kryn.
- In A Time To Kill, the Tenth Doctor completely shatters James Bond's cover, and the spy is injured in the ensuing fracas.
- Real Men Don't Make Sandwiches: The whole reason Krillin is staying at Capsule Corp in the first place and winds up making his deal with Vegeta is because Goku kept breaking the water main at Kame House. Why? Because after Trunks' warning about the Androids, Goku has started worrying that his best friend might get killed in the fight, and has been trying to convince him to move closer so he can protect him better. His well-meaning but overbearing efforts have only inflamed Krillin's inferiority complex, and when he realized that Goku was willing to sabotage Kame House in order to force the issue, responded by running away, repressing his ki so that nobody can sense where he is. Which, in turn, has only made matters worse as nobody other than Vegeta knows where he is and are naturally worrying about what might have happened to him.
- In Dragon Ball Z Abridged: The History of Trunks the Androids eventually get bored with killing humanity. 17 decides he's going to stop killing and become a park ranger instead... right before Gohan kicks him through a building. A pissed 17 resolves to kill every human in response, and then he'll "range the shit out of that park."
- In Memento Vivere, a Final Fantasy X fanfiction, Jecht forces the party to flee the battle after he tosses his sword at the Espada, thereby losing the weapon. He does it again when he attacks the Moonflow Shoopuf.
- Us and Them: Vincent searches for Sephiroth for seven years, finally tracking him and his adoptive family down to Corel. However, unbeknownst to him, Hojo was tracking Vincent's moves, leading the Shinra to find and capture Professor Gast and Ifalna. Sephiroth is furious when Hojo taunts Vincent for leading him straight to the family.
- The Power of Seven: This is the best way to sum up Ron's mistake in chapter 26; he reveals to Lavender that Harry is having sex with Ginny, Hermione, Luna and Demelza because he believes that Lavender is dumping him for Harry, when in reality she dumped him for Seamus and had no idea about Harry's sexual activities before Ron brought it up, thus leaving that information to be exposed to the rest of the school.
- In The World as We Knew It, Harry, Remus and Snape create a world where Voldemort never fell out of an idle wish (unwittingly invoking an ancient magic that grants a wish if its independently made by three different people at the same time), and their attempts to defeat this worlds Voldemort lead to the decimation of whats left of the Order of the Phoenix, including the still-living Lily and James.
- In the backstory of Meant to Rule this World, Dumbledore used an illusion to make Tom Riddle believe he set the boy's things on fire in an attempt to teach him stealing was wrong. Instead, he solidified Tom's beliefs that Might Makes Right.
- In Irreversible Destiny Harry's mother had a prophecy claiming that she should repay Merlin's debt to his mentor Blaze by having a child with Blaze's last remaining descendant. Unfortunately, said descendant happens to be Snape, who, as an Inner Circle member, was subjected to potions and spells intended to create a small army of powerful Death Eater offspring utterly loyal to Voldemort. It also doesn't really help that as a descendant of Merlin on his mother's side, incubus blood was added to the mix.
- In New Blood (artemisgirl), Lupin ignores Hermione's warnings about making students publicly the Boggart in 3rd Year. Not only do we witness 3 examples of child abuse, including a pedophile, but one student, Hermione, collapses screaming at her Bogart. The Fallout of Hermione's fear, A newspaper on London going up in a mushroom cloud, sends shock-waves through the school resulting in the highest Anti-Muggle sentiment in living memory.
- Hermione accidentally overpowers a Summon Magic ritual resulting in a much stronger type of Air Elemental than intended Luckily Luna is able to bargain with it rather than be possessed.
- Game Theory has quite a few examples. The two most notable are Chrono assuming that Nanoha was working with Fate and attacking her in her home, which led to her actually deciding to help Fate fight the TSAB, and Nanoha's consequent decision to help Precia revive Alicia.
- The One to Make It Stay:
- Alya causes a considerable amount of trouble when she films one of Chat Noir's Love Confessions, edits the footage to make it appear that Ladybug reciprocated, and posted the results on her blog. With this one move, she effectively tanks the trust Ladybug had placed in her, encourages the already entitled Chat to step up his efforts, damages her readers' faith in her, and provides Hawkmoth with valuable insight into the heroes' dynamic.
- Alya causes further breakage among her readership with how she handles the fallout. When commenters attempt to point out how the footage was obviously cut up and edited, she deletes their remarks. Naturally, this doesn't cause the criticism to just go away, only serving to throw fuel onto the fire.
- Chat's refusal to take 'No' for an answer, combined with his jealousy of Viperion and blaming him, Ladybug and the other heroes for all the tension his behavior is causing, ultimately culminates in Hawkmoth successfully exploiting his crush to steal the Black Cat Miraculous. This means that Plagg ends up in the enemy's hands, Adrien loses his Secret Identity and all that came with it, and Master Fu is forced to leave Paris for safety's sake.
- BURN THE WITCH:
- Adrien convinced Marinette to stop trying to expose Lila's true nature to their classmates, reasoning that her lies would catch up to her eventually. What he failed to consider is that this would leave her free to continue until the truth came out, and the amount of damage she could do in the meantime.
- Not only did Rose donate a lot of her own money to Lila's nonexistent charity, she convinced others to donate as well. Everyone who trusted her word got burned, including Prince Ali, who is understandably furious when he learns the truth and breaks off their friendship.
- In Modurn Warfare 3 The Dead Rise,
Soap Soup throwing a knife into General Shepherd's eye triggers his demonic powers, enabling him to come back even more powerful than before.
My Little Pony: Friendship Is Magic
- In The Lunar Guardsman, it's what a few ponies in Baltimare try to invoke after the death of Charybdis and the damage it caused in Horseshoe Bay. Judging by the news articles, and the proclamations of support and thankful letters sent to Luna however, it didn't quite take.
- In Chronicles of Harmony's End, Array conspires with Discord to overthrow Harmony (the only force keeping the two of them in line), believing he could destroy Discord himself. He was wrong.
- Inner Demons: If Celestia had told Twilight about the prophecy sooner, or broken the news to her differently, it's possible that perhaps Twilight's transformation into the Queen of Darkness could have been slowed or altogether prevented. At the very least, Twilight wouldn't have freaked out and turned Celestia to stone in a fit of anger at the revelation.
- Twilight actually pulls this on herself. After the above incident, she convinces her friends to lock her up in the library basement while Rarity searches for a way to stop her descent into darkness and free Celestia. Unfortunately, since Spike is busy helping Rarity and Twilight's all alone, there's no one to wake her up from her nightmares, wherein the Queen persona consumes her completely.
- A little later on, Sweetie Belle is on the verge of a Heel Realization, when Rarity's unfortunate wording during a conversation hits an emotional trigger Queen!Twilight had previously planted, causing Sweetie Belle to fully embrace her FaceHeel Turn and reject Rarity as her sister.
- Apple Bloom ends up accidentally killing Trixie, whose death causes Queen!Twilight to suffer a Villainous Breakdown that results in her transforming into an Alicorn.
- In A Minor Variation, Rarity sends the CMC to deliberately provoke a disharmonious event near the statue of Discord to see if he was showing signs of breaking loose. Oops.
- There are no words to describe Celestia's epic screw-up in Past Sins. Suffice it to say that if she had just held back, almost none of the really bad things would have happened.
- The Ponies of Olympus series:
- Ditzy Don't: Twilight's attempt to help Ditzy by implanting magical copies of the Mane Six's personalities in her head first causes her to outclass Rainbow Dash to the point of her public humiliation, then all the group's negative aspects (Fluttershy's sudden rage, Pinkie's personalities, Twilight's obsessiveness, etc) take over, making her go crazy and chase after Rainbow Dash to force her to let her take care of her.
- Rolling in Beaches: Wavedancer taking the Rainbow Pearl out of curiosity (and then keeping it to get close to Spike), leads to it being stolen by the Scaly Back River dragons, who in turn break it and accidentally release the Rainbow of Darkness.
- The flashback at the beginning of Atlas Strongest Tournament incorporates the story of Tithonus, with Celestia as the guilty party.
- When Rarity saw Ran Biao and Razorwing together, she ran away at the perceived betrayal, which led to Razorwing raping Ran. This led to the breakup of their friendship.
- The Pony POV Series:
- Fluttercruel honestly just wanted to teach Fluttershy something important for her own good, to let her learn the cruel part of nature, but it ends up corrupting her for real as opposed to being just brainwashed by Discord. Fluttercruel is absolutely horrified realizing this.
- She also gets Fluttershy, and herself, drunk, which Word of God admits may have had something to do with their behavior following and made Fluttershy more vulnerable to the darkness than she otherwise would be.
- While it's Loose Canon, it's implied that the Mane Cast are, unknowingly, being manpulated into commanding Princess Gaia's army via a boardgame they're playing with Gaia herself. If this is believed, Rainbow Dash unwittingly guides Gaia's army into "Gaiafying" Gilda.
- If this is true, it is quite possible that Trixie and Twilight Sparkle are unwittingly providing a front for Princess Gaia to brainwash their own mothers into being her knights.
- In the aftermath of a battle, your friend-suddenly-turned-enemy lays indefinitely helpless before your group. To help console each other on this tragedy and related circumstances, one mentions that it is not too late to restore or redeem this friend. If you think that taking matters into your own hooves and executing your petrified former friend, Discord, by pulverization is not a logical next step, you are smarter than Galaxia, whose deed costs her life, sets the stage for a 1000 years of tyranny, and worst of all, could have been easily avoided.
- During the battle between the Dark World!Elements of Harmony and Discord's remaining minions, Spike has to choose between helping Rarity and Twilight, both of whom got separated from the main group while fighting Fluttercruel and Angry Pie (respectfully). He figures Rarity will need more help and goes after her; in fact, not only has Rarity by this point killed Fluttercruel, but Twilight ends up overpowered by Angry Pie, who rips out her Element and leaves her for dead.
- In Secrets and Lies, Twilight tries to prevent Discord from escaping without alerting anypony who doesn't need to know what's going on, in order to avoid triggering mass panic. On top of this, she's keeping other secrets from her friends, and her attempts to fix everything without revealing them lead to terrible complications. Her biggest break, however, is when she determines the best way to help Fluttershy is to have her commited, leading to her getting dragged away kicking and screaming and locked up in a madhouse.
- In Screwball Over, Twilight Sparkle and friends discover that their attempts to cure their friend and neighbor Button Stitch of her tendency to turn into her Toon Physics-powered alter-ego Screwball were all part of a plot by Discord to summon an endless swarm of mini-Screwball clones and swamp Equestria. Discord, having been turned back into stone at this point, has left a message mocking Twilight for falling right into his trap with her goody-goody ways. Twilight is only saved from a Heroic BSoD by the reassurances of her friends and the princesses that she shouldn't blame herself.
- Anthropology: If Lyra didn't want to be a human so badly, Discord would have never found Earth in the first place. Naturally, he takes great pleasure in pointing this out to her.
- Pulled on the readers in Dungeon Master Bonbon. When Lyra temporarily takes over the blog, they spam her with asks saying how Bonbon loves her, causing her to break up with Bonbon out of fear she's leading her on.
- In A Stranger Among the Voices, Twilight and her friends have an offscreen incident early in the story that involved repelling a chimera and forcing it back into the Everfree Forest. At this point, the reader can guess this is the same chimera that attacked Dinky in the previous chapter, which wouldn't have happened if Twiilght's timing had been a bit later, as she notes to herself.
- The eponymous Villain Protagonist in The Rise of Darth Vulcan's main occupation-aside from looting ponies- is calling out the ponies for their dumb actions in canon. In-universe, many of actions of the Mane 6 and others make the situation with him a lot worse:
- Twilight tried to get rid of the Alicorn Amulet by dumping it in a void, which allowed it to reach Ted, and gave him the power to become Equestria's next villain.
- Rainbow Dash attacked Darth Vulcan immediately when he entered Ponyville because of his hostile nature and evil-looking armor.
- The Mane 6 use the Elements of Harmony on him, thinking he was brainwashed by the Amulet. Not only was he not brainwashed, he believes the Mane 6 were trying to brainwash him. In their defense, the Mane 6 didn't realize the true effects of the power of Harmony, something Luna also claims are not pleasant.
- Filthy Rich attempted to sell Vulcan out to the authorities and take his bits anyways. This resulted in Diamond Tiara being kidnapped and Ponyville being looted. He was very traumatized by these events.
- Luna tried to interrogate Vulcan by beating him up. Not only was she given a brutal Hannibal Lecture which drove a wedge between her and Celestia, she also exacerbated the trust issues of what was deduced to be an angry teenager. She is ashamed when she realizes this, but by then it was too late for her to make amends.
- Twilight ignored his hatred of mind influencing magic and brought mind-changing spells to his trial. It's no wonder he didn't stick around to help stop Canterlot Castle from falling into a lake.
- Celestia allowed the ponies of Equestria to brainwash the thestrals into thinking that their need for blood was a mental disorder when it's about as much a disorder as the desire for water and force them to use a woefully inadequate alchemical substitute. As a result, fifteen thestrals have defected and joined Darth Vulcan. And when the Princess finds out, Celestia flat-out bans her from doing anything about it, destroying the last bit of the Princess's trust in Celestia. All this for no better reason than that the ponies of Equestria find the thestral's need for blood creepy.
- Luna also evoked this trope when she created the Thestrals by using vampire bat DNA in the process, causing the need for blood, instead of a species of bat that ate something innocuous like fruit or nectar.
- Rites of Ascension:
- Luna pulls this on Celestia after Shining Armor is fired from command of the Royal Guard by inducting him as the leader of her Night Guard, to allow him to secretly continue investigating the conspiracies. Celestia had seen the attack on Shining coming and had been grooming him as a populist voice in the courts, which was central to most of her near future plans, but she didn't tell Luna because they always ended up butting heads over long-term strategy and she didn't tell Shining so he, and their enemies, would believe he was no longer a threat. Not only does Celestia's plan go up in smoke, but she worries that the relatively unsubtle Shining will be caught doing more than is strictly legal for the Night Guard, at which point Luna's crown and authority (and Celestia's own, if she steps in) would be pretty much bucked. Celestia's setup of all this also means that she played this trope on herself, but since Luna acknowledged Celestia might well have a plan but was tired of being left waiting in the dark, she really has no excuse.
- Twilight thinks this of herself after her espionage mission triggers a war between Zebrica, Saddle Arabia and Equestria. Considering things had been volatile for a while, and she stopped a cult leader from wiping out the whole Zebrican continent and triggering worldwide damage, no one else agrees.
- Fall of Starfleet, Rebirth of Friendship: Thanks to Starfleet's tendency to send anyone for crimes such as thinking Celesto is wrong to far-off prison planets, Dark Conquest has a huge army who's all too willing to follow him if it means killing Unicornicopians.
- The Clockwork Consequence... Hoo boy! Let's just say that Twilight's Batman Gambit to escape from Nightmare Moon in the Night Mare Moon timeline from The Cutie Re-mark Part 2 was not one of her better ideas. But, to be fair she had no idea just how far Nightmare would go to protect her rule.
- During Octavia's fight with the minotaur in Stroll, she accidentally hits the knob to one of the burners on the stove, setting Sesame Seed's apartment on fire.
- In The Conversion Bureau fanfic The Conversion Bureau: A Beacon of Hope the nationstate of New Athens was created when Celestia tried to convince Socrates the Wise to teach about the magic of friendship. That caused him to have a Freak Out, smash his horn against a wall removing his magic permanently and leave Equestria. Then the other newfoals started following him and..
- The Meaning of Harmony: Princess Celestia's desire to activate the Forges and bring true Harmony to Equestria nearly ended up destroying the entire world instead.
- Loved and Lost: Right after Twilight has stopped the Changeling invasion by shrinking the Changelings, Prince Jewelius blames all the other heroes for the invasion, telling the wedding guests and royal guards half-truths about the canon mistakes Princess Celestia, Shining Armor and Twilight's friends made before the invasion. Even Celestia is taken aback by her previously well-mannered nephew's hostility, so aside from nervous requests for him to calm himself, she doesn't try to stop him. She tries to claim that everything would have been resolved differently if Twilight had acted calmly and gathered evidence against the disguised Queen Chrysalis at the wedding rehearsal, but Jewelius overrules this argument by bringing up Celestia's own decision not to postpone the wedding and fully focus on the lingering threat of unknown attackers. When he gives everypony in Canterlot a New Era Speech in which he promises to rectify the collateral damages of the invasion, Celestia tells the panicked heroes to run. This majorly backfires for the heroes because not only does the escape attempt fail, but it also gives serious plausibility to Jewelius' slander about the heroes, so the guards imprison them on his orders, about everypony in Canterlot starts to despise them, and Jewelius makes himself Equestria's respected king.
- In The Enchanted Kingdom, Twilight, Rarity, and Pinkie come up with a plan to free Princess Luna - by getting all the foals in Hollow Shades to believe in her strongly enough to overcome the chaos magic imprisoning her. It completely backfires; the foals start losing their belief and having nightmares, and the magic transforms Luna into Nightmare Moon.
- A Diplomatic Visit: In the seventh chapter of the fourth story, The Diplomat's Life, Twilight and co. perform a spell to bring back the Pillars of Equestria... but also release the Pony of Shadows, who promptly heads off to free his people from their own prison. (Admittedly, she was prepared for his return, but the spell she intended to stop him turned out to be not strong enough.)
- Escape From The Hokage's Hat has Shizune not let a recovering Naruto (who just wants to provide support) fight by slapping him with a Interface Screw jutsu. This ends with Hinata (literally) getting stabbed in the back, Shizune too tired to heal Hinata while the enemy attacks, Naruto using a Forbidden Dangerous Technique that could've fried his charka network to save them and her losing Naruto's trust. She, however, at least notes how she screwed up and starts fixing the mess.
- Blackkat's Reverse has Kakashi forcefully ripping Naruto from his newfound uncle's arms and refusing to hear Kurama's plea to not separate them. It results in Kurama kicking his ass, abducting Naruto and fleeing Konoha.
- In The Last Prayer, Ino and Kurenai investigating Naruto's mistreatment results in him getting banned from the last two stores that sell to him and his landlord running off with all his tenants' rent money, meaning Naruto and anyone else in the building now has no water or electricity and is facing eviction.
Neon Genesis Evangelion
- Discussed in The Second Try: Asuka and Shinji lived for a while in a barren world because they were unknowingly furthering a "wipe humanity out" scheme when they were fighting alien monsters... and because Shinji was sick of everything. In the fourth chapter, Shinji states that all of humanity is gone because of him. Later on, Asuka and he admit that they were part of the trouble in the original timeline just so much like everything else.
- In Clouded Sky, it turns out that Waytar's Shield was keeping all of the ghosts in Waytar trapped there, and by destroying it, Tobias sets them loose on the outside world.
Rizzoli & Isles
- In the supernatural AU Blood & Teeth, it turns out that Charles Hoyt survived his death; he was a werewolf who was being used as the test subject for a serum that would suppress the ability to transform, but after his death his body was retrieved and revived so that they could confirm if the drug was the reason for his cancer, which allowed an associate to help Hoyt escape.
- Marque and Reprisal: Or Nice Job Fixing It, Villain!, depending on one's point-of-view. A tribe engaged in ethnic cleansing in the Serengeti region of Africa during the Global Civil War. A child of the enemy ethnic group survived a massacre and was adopted by a family- who proceeded to abuse him horrifically for over a decade solely because he was of the "wrong" ethnic descent. Four decades later, the child, now a grown man who is a Space Marine colonel, comes back, organizes a militia, and begins an ethnic cleansing campaign against those who shared the blood of his abusive family. And he succeeds, with the remnants of his adoptive family's ethnic group fleeing the Serengeti.
- Children of Remnant: By attempting to assassinate Jaune, all Kali manages to accomplish is pushing the world towards a war and antagonize the Claimed into open combat.
- A Rabbit Among Wolves: Team RWBY's interference in the dock heist backfires on them in every way. They ruin the White Fang's ambush, get into a petty argument with them that gives Roman Torchwick all the time in the world to steal the dust and escape scot free, the ensuing fight causes massive property damage that they wind up being blamed for, and they don't even manage to capture any of the White Fang members. Last but not least, Lisa Lavender uploads a video of the events online soon after, edited to remove any scenes that'd make the White Fang look bad. All of the above guarantees that Beacon will face a PR nightmare trying to explain why four of their students caused such a mess.
- In the fan fic Before the Dark Times Obi-Wan does the very thing Anakin pleaded with him not to do and told the Jedi Council about his use of the Dark Side, once by accident and his marriage to Padme. This in turn causes the council to throw Anakin out of the Jedi all the while lecturing how it's impossible to come back from the dark side once one starts on that path. This is including the years of Mace Windu doing nothing but being a condescending jerk to Anakin. Needless to say all this sends Anakin right to Palpatine who is more than happy with these developments and helps turn Anakin into Darth Vader. And for extra Mace flat out tells Anakin that the Jedi are going to take his children to be trained to become Jedi as infants regardless of what Padme or Anakin wants.
- Discussed in The Wrong Reflection. Gul Morag of the Klingon-Cardassian Alliance in the mirror universe blames Starfleet for the resurgent Terran Empire. It's mostly accurate,* but Captain Kanril Eleya refuses to be held responsible for it because all it happened before she was born and Julian Bashir and Kira Nerys were only doing what they had to do to escape Alliance imprisonment. Still, it is the fault of the prime universe Ferengi that the Terrans now have cloaking devices, something which Eleya fixes by giving the Alliance Starfleet's data on how to defeat a cloaking device.
- In New Home, Peridot and Steven realize that the Crystal Gems are attacking all the Homeworld grunts that were send to help neutralize the Cluster, potentially dooming the Earth to destruction and rendering Steven's efforts meaningless.
Sword Art Online
- In Sword Art Online Abridged, Sachi's hit by a double-whammy of this. She encouraged Kirito to act nicer toward his guildmates, so he agreed to a plan he thought was stupid to make her happy. Except the plan was stupid, leading to a near-wipe and Sachi's death. Then Sachi tried to comfort Kirito with her dying words by assuring him "This isn't your fault," except due to her lag it comes out as "this isn't your fault — your fault -- your fault -- your fault," mentally scarring the little bastard and turning "your fault" into his Trauma Button.
- New Tamaran: Rather than exposing Lex Luthor's crimes, Oracle blackmails him into becoming an Honest Corporate Executive. This allows him to exchange tools with Blackfire for the murders of Starfire and Supergirl, triggering a war between Earth and the Tamaraneans.
- In Courtney's Crusade for Redemption Courtney, once she forces Alejandro's early Robotic Reveal, decides to get even on him for his past misdeeds by pushing him to the lake; Duncan saving him convinces Chris to send Duncan to the heroes' team and Courtney to the villains' one, something that she wanted to avoid.
- In Legacy, the would-be rescuers burst into the lodge at exactly the wrong moment. Tragedy ensues.
- Everything in Imperfect Metamorphosis can ultimately be traced to Team 9, and Cirno specifically. They were responsible for both releasing the Shadow Youkai and getting Yuuka involved, and their constant meddling continued to make things even worse. Other characters caused a lot of headaches too (especially Eirin and Yukari), but only Marisa, due to having stolen the box from Patchouli in the first place, allowing Team 9 anywhere near it, is anywhere near their level of blame.
Tsubasa -RESERVoir CHRoNiCLE-
- When Fai finds out about R!Syaoran and Kurogane's Secret Relationship and the fact they were sleeping together in Shatterheart, he forces an ultimatum for Syaoran to either to tell the truth to Sakura or to break up with Kurogane, which he sees as an extremely codependent relationship. This has the side effect of deteriorating Fai's budding reconciliation with Syaoran. His earlier ostracization and hatred of the latter and forcing him to end his only positive relationship proves the straw to break the camel's back and Syaoran wants nothing to do with him. Since Kurogane was the only one Syaoran could turn to for comfort, his PTSD gets worse and he mentally and emotionally falls apart.
- Okay, Luminosity's only difference is that Bella's a different character, so naturally the differences for good or ill will be her fault...village murdered because of her? And now the Volturi have shapeshifters on their side? Because Bella thought it would help them. Oops. And Elspeth is following in her mother's making-the-Volturi-stronger footsteps.
- All Guardsmen Party: This is the result of sending a Knarloc to fight a Chaos servitor-Titan-techpriest. What's left of both fuses together, remains Chaos-possessed, and is significantly angrier at the Guardsmen.
- Trading a Necron flyer to a Rogue Trader. Several worlds are cleansed of life by the Necrons chasing after the flyer, and a schism in the Mechanicus is threatened. And that's before the Hereteks get in on the madness.
The World Ends with You
- Eri's Game: Because of her fight with Higashizawa, Shiki unknowingly let her best friend, Eri, get her death wish. Oops.
- With This Ring: It's Martian Manhunter's fault that the Team gets trapped in a mental training simulation due to M'gann freaking out because he didn't properly assess her capabilities. It was his fault that he deliberately made the simulation unwinnable that Orange Lantern becomes so desperate to save his friends and the remaining survivors that he summons the Ophidian. In the simulation, Manhunter kills M'gann to end the simulation in front of the Ophidian-infused Orange Lantern. This traumatizes Orange Lantern and cause his mind to fuse with the Ophidian's.