- In the fanfic Cat-Ra, Shadow Weaver manipulated Adora with the intent of making her more cruel and ruthless. Adora realizes what kind of person Shadow Weaver is and betrays her to Hordak without a second thought while giving her a brutal Breaking Speech.Shadow Weaver: I've created a monster.Adora: No, you've created your replacement.
- Orbko was designed to learn from and adapt to any obstacle that interfered with its mission, and the results far surpassed Entrapta's expectations. Unfortunately, when its priority to defend itself and its orders not to harm Frosta come into conflict, it decides that its own programming is an obstacle and overwrites it to reclassify Frosta as an enemy.
- In Hackbent, Alleph desperately wants to be taken seriously when he 'commands' his friends and constantly fails. In an alternate timeline he finds out his god tier powers allow him to literally do that. It directly spirals out of control, ends in a massacre of his friends, with the only survivors being Morson and Cyrill.
- In the Death Note fic Tired & Emotional Light adds a little brandy in L's ice cream in an attempt to loosen his tongue so he might learn his true name. Light gets L drunk, alright...
- In the fanfic Duel Nature, Twilight Sparkle Got Volunteered into a duel with Princess Luna. While it was supposed to be a friendly match, emotions quickly got out of control: in an effort to break Luna's concentration, Twilight resorted to psychological warfare, using her knowledge of the princess to hurt her, culminating in a full-blown Break Them by Talking moment, which did disrupt her concentration, but turned a sparring match into a deathmatch.
- In the Fallout 3 mod Mothership Zeta Crew, the PC and company explore an underwater base of the aliens. However, there are no live aliens around. They were killed by Tyranids/Xenomorphs. Later, the PC finds out that The 'nids/'morphs were there because the aliens made them to attack the Olympus. Turns out, they were good at attacking. The aliens.
- Thirty years prior to the events of Sonic X: Dark Chaos Luke the Seedrian - the future Dark Oak - roboticized a young fox named Tsali into the "Ultimate Weapon" that could save his homeworld from a Demon invasion. Tsali quickly freed himself, promptly turned against his creators, and exterminated the entire Seedrian race in revenge.
- In He Can't See It, Marcie helps Xander by pretending to be his psychic powers. Unfortunately, due to how unstable she is, she goes too far and Xander nearly kills himself to protect Buffy and Willow from his out of control powers.
- Rosario Vampire: Brightest Darkness:
- In Act I chapter 12, Apoch and Astreal brainwash Rason and Dark for aid, only for their master to exploit this and use all four of them as his mindless slaves.
- In Act I chapter 23, Yukari, hoping to help Tsukune and Moka's relationship, creates a special Love Potion that literally makes someone dosed with it crazy with love; as Yukari puts it, "you may not want to be in public then." However, Yukari never anticipated that Moka would share the potion with Kurumu and Mizore during school hours, rather than use it for herself when she and Tsukune are alone.
- Talon Ryashen's Backstory. He was kidnapped off the street by Fairy Tale and turned into a Super Soldier. The minute the experiments were complete, he escaped the lab and now seeks to wipe out anyone and everyone who ever worked for Fairy Tale as revenge for the loss of his humanity.
- In Wind Lord, one of Naruto's enemies uses a jutsu to de-age Naruto until he's an infant. He goes too far and temporarily unleashes the Kyuubi.
- In Mass Effect Human Revolution, the Templars wanted to make Hannibal a killing machine to use against Adam. He did become a killing machine... against them.
- The Big Bad of Angel of the Bat revolves around this. Deacon Blackfire groomed Daniel Lebowitz to believe he was a messiah. The success created The Seraphim, whose ego was so great that he betrayed the deacon and stole all of his followers.
- The premise of Wish Carefully is that, instead of taking up the fight, Harry Potter surrendered Wizarding England to Voldemort and the Death Eaters, arranging for everyone else that was loyal to the Light to be evacuated. The Death Eaters now rule England without any opposition or Muggle-blooded taint... with all of the problems that would naturally come with what they wanted. Voldermort's England has no genetic diversity to prevent inbreeding defects, no working class, no skilled professionals, and an economic infrastructure that can't support them. On top of that, their leader is a murderous psychopath who starts making Dark Marks burn on people just to stave off his boredom. Lucius Malfoy notes in his journal that the Light's plan was deviously ingenious, because it let the Death Eaters destroy themselves while the Light doesn't have to do anything but sit back and watch.
- in Zero Interface, a trio of students learn of Ranma Saotome's phobia of cats and decide to antagonize him using wind magic to make it sound like he's surrounded by cats. This results in Ranma (and via their bond, Louise) activating Neko-ken and going on a rampage.
- In Community Service, most Death Eaters escaped Azkaban after Voldemort's first fall by getting sentences to two years community service, and Voldemort, as in canon, has cursed the position of teacher of Defence Against the Dark Arts at Hogwarts to neutralize whoever held it before the first term ended. Then Dumbledore had the brilliant idea of having said Death Eaters spend their sentence as DADA teachers: the lucky ones are the two who merely lost their magic.
- The dragons of RainbowDoubleDash's Lunaverse are a Dying Race precisely because they have such impressive natural advantages. While most races must band together for trade and protection, a dragon's only need is for rocks to eat and they are so powerful that by far the biggest danger any dragon faces is another dragon. As a result of this, dragons have no society to speak of. They don't trust each other, and because they don't trust each other, they don't work together. Their whelps are essentially abandoned to fend for themselves, since no adult would take in a whelp for fear of that whelp stealing some of their hoard. Only a handful of dragons can even read or write.
- This is played with in the My Little Pony: Friendship Is Magic fanfic How To Kidnap A Princess where Rainbow Dash and Pinkie attempt to kidnap Twilight Sparkle in order to convince her that her castle's security is too light. It's played with in that Twilight gets wise to their plan and tricks Rainbow and Pinkie into kidnapping a clone from the Mirror Pool. The "horribly right" part comes into play when their little prank ends when Princess Celestia and Princess Luna come down on them personally for high treason and imprison them in Tartarus for kidnapping a Princess.
- M4K30V3R, Rouge's "automatic beautifying system" from Sonic's new look (and multiple similar stories). Intended to make sure Rouge always looks her best, it does it's job flawlessly. So when it finds Sonic in her room...
- Overlaps with Be Careful What You Wish For in the MLP fan comic series Trixie Vs, Trixie repeatedly states her desire to learn how to fly using levitation. Then at one point, while messing around with a spell that magically turns her back into a filly, she gets the bright idea to test her levitation flight, while she's a child, hoping that her lighter size would make it easier to left herself off the ground. It not only works, but works out so well, she end up on the moon!!! with no feasible way of getting back down.
- In Professor Arc this trope makes up the basics of the plot. Just like in base material, Jaune manages to fake his transcripts and get into Beacon... except here it works so well, that it lands him a job as a teacher. You can probably figure out what comes out of it. Later on, his ruse becomes so successful, that when the only way to defeat Cinder's plan is to confess, he is completely disbelieved by General Ironwood, who sees Jaune as a dangerous mastermind.
- In the fanfic Zootopia: Lone Digger (a crossover between the film and music video for the song by Caravan Palace), a landlord is trying to close down the Lone Digger Club by arranging a brawl between patrons. Instead, he gets the bloody slaughter depicted in the music video.
- In Christopher Weston Chandler & Magi-chan's Stone, Bob, sick of dealing with Chris, wishes the wizards would kidnap Chris (though he reconsiders after talking to one). They do take Chris away, but he ends up going to Hogwarts. Meaning he'll come back with Bob helpless to his antics.
- The Raven's Plan opens with the last survivors of Westeros holding a Last Stand against the Night King's forces while Bran and Melisandre conduct a ritual to send them all back in time so they can change things. This spell is powered by blood, and no one took into account all the blood the defenders would be spilling, leading to the ritual being supercharged. So, yes, it does succeed in sending all its targeted people back, it's just that a lot of other people also get sent back, throwing the plan Off the Rails.
- In Neither a Bird nor a Plane, it's Deku!, Bakugou demands that Izuku train for the entrance exam because there's no way someone who spent ten years trying not to become a Hero is going to get in. Izuku ends up taking that advice and walks away with the highest score in the exam's history. Worse still, his actions as The Paragon also inspired everyone to start helping each other, which knocks Bakugou down to the bottom of the Top 10 rankings.
- In Brilliant Lights Will Cease To Burn, Izuku calls the cops after busting an underground fighting and human trafficking ring to let them clean the place up. He did not expect them to send All Might, who then proceeded to cut off Izuku's only avenue of escape.
- Dial: Titania attempts to use her love powers on Rath!Dial. This works. Unfortunately, Rath, as an Appoplexian, believes that the most traditional, romantic thing you can do to someone you love is to beat the tar out of them in a battle.
- The Dark Lords of Nerima: After failing to kill the Sailor Senshi and subsequently fleeing, the youma Beneda falls in with Ryouga and Ranma in the hope that they'll kill her enemies for her. This leads to them defying all of her expectations by taking on Jadeite and winning, then eventually taking the fight to the Dark Kingdom itself.
- The whole "Dark Lords" plan come the sequel. The Senshi still think they are world-conquering villains and as such are quite prepared to use lethal force against them, especially the Outer Senshi.
- In Chapter 55 of In The Dark, Geri was able to get Melanie to see a hypnotist in hopes of getting any of her memories. Since there was a court official, it would help ensure that Otis Darwin pays for what he did to Melanie. Cue the Mass "Oh, Crap!" once Melanie realizes what she had revealed.
- Captains Crash: Hiring a Captain Crash to pass on his skills at crashing safely? Sure, he succeeds, so injuries go down. But he also causes his students to start forgetting their skills at landing without crashing, so incidences of crashes go up. By 390%.
- Halloween Unspectacular: The first collection's Big Bad, ReGenesis, was the product of a government project to create a Physical God. The project was a success, but (partly thanks to his status as a Chew Toy pre-transformation) said god quickly turned out to be an Omnicidal Maniac.
- Parodied in Yu-Gi-Oh! GX: The Abridged Series, where some students tried to summon Jinzo... and they did!
- In Sword Art Online Abridged, Rosalia subjects Kirito to a Breaking Speech intended to reduce him to a gibbering wreck before she and her Titan's Hand goons mug him. However, this doesn't change the fact that Kirito is still thirty levels higher than them, so they can't even harm him even when he's not bothering to dodge their attacks. All Rosalia succeeds in doing is turning a Jerkass into a Laughing Mad killing machine, then slamming several of his Berserk Buttons, which turns out to be a fatal mistake.
- In Naruto Myoushuuno Fuuin, Sarutobi's efforts to hide Naruto's parentage are so successful that the boy believe he's the Son of a Whore and one of her clients. Kakashi and Jiraiya are both furious with Sarutobi when they learn this.
- Three Guys Go to a Bar (And Then They Beat You With It) centers around Principal Nedzu and Aizawa assigning Bakugou, Tokoyami and Shinsou to play villains in a series of exercises against the rest of their classmates for their final exams that semester. They correctly figure that the three of them will take the exercise seriously, but severely underestimate just how angry the trio will be at being typecast due to their 'naturally villainous' Quirks. Spite proves to be a powerful motivator, indeed...
- In The Loud House fanfiction Boys And Girls, Lincoln reminds Lori of Bobby to get her to stop fawning over Hugh. It works, but also makes her cry.
- A Rabbit Among Wolves: Jaune manages to succeed well enough in his first mission, that Sienna Kahn expects him to expand his work and recruitment, rather than just lay low like he wanted until he could convince the public he wasn't evil. Being in a terrorist organization, he knows what would happen if he refused her orders.
- In Marc Being In A Gang Rights, in the very first chapter, Marc's gang snatches Nathaniel and holds a knife to his face and threatens to harm him if he hurts Marc in anyway, hoping it would scare Nathan enough not to pull anything with Marc. What they weren't intending was for Nathaniel - who is being ganged up by a group of strangers in an alleyway, pinned to a wall with a knife in his face - to start wailing in terror and bursting out into tears.Male Gang-Member #1: Oh shit, are you crying? Yeah, I'm not dealing with that.
Marc's sister: Hey, uh, maybe don't cry?
Nathaniel: YOU WERE JUST THREATENING ME WITH KNIVES, WHAT DO YOU MEAN?
Male Gang-Member #2: Shit, Marc's gonna kill us if we made his boyfriend cry, abort, abort!
- In Danganronpa: Academy of Discontent, Fuyuhiko and Peko both try to take the First Blood Perk at the same time, allowing them to escape together without a trial. They succeed in killing their targets, but because Monokuma could use the security cameras to pinpoint which victim died first, he granted the perk to Fuyuhiko only, and had him removed from the academy and apart from Peko.
- Doctor Ghemor I Presume has the Obsidian Order abducting Dr Julian Bashir and gaslighting him into believing he's one of their agents to launch a sting operation on said disappeared agent's father. Courtesy of Julian's rather delicate relation with reality and craving for genuine caring bonds, he eagerly embraces Legate Ghemor as his father. Entek is left a bit flummoxed by this development.
- In Thin Line Between Love and Hate, Sasuke, out of frustration and annoyance at his fangirls, gives each one a breaking speech to make them lose their admiration towards him and leave him alone (he also gives one to Hinata for her admiration towards Naruto). This not only breaks any infatuation towards him, but sets the seed for intense hatred at him, enough that one all-kunoichi team (composed of Ino, Sakura, and Hinata) are plotting to destroy him.
- In the A Hat in Time AU fic What to Expect When You're On the Run, Vanessa uses The Baby Trap to get Michael to leave his university and be with her more permanently. She succeeds alright, and Michael stays with her to care for his daughter. Unfortunately, Vanessa becomes a Jealous Parent when she feels Michael is spending too much time with Harriet (said daughter).
Gone Horribly Right / Fan Works