Interpersonal conflict amongst close friends, family, or lovers is almost always hard to navigate, not least of which because of the overlapping social circles between the feuding parties. Forcing someone to pick a side is a great way to alienate others and make them either side with the other party out of spite or distance themself from you entirely to avoid being roped in.
That is, if you tell the truth. Lying or manipulating your shared friends and family to view you as the sympathetic party is always an option. If you choose to do so, congratulations, you've just run an Insidious Rumor Mill.
Running an Insidious Rumor Mill involves lying and telling half-truths and/or omitting relevant favorable details about another person within one's same social circle in order to turn that circle against them, isolating, ostracizing, and ideally, ousting the victim from the group entirely. Unlike with Gaslighting, the goal isn't to get the victim to believe your lies and narrative, it's to get people you both care about to view them as so despicable, petty, or toxic that they are not to be trusted even if they are telling the truth. It's character assassination designed to emotionally destroy the victim by cutting them off of their support network, made possible because it's also your support network.
A common tactic of the Alpha Bitch, Bitch in Sheep's Clothing, and Manipulative Bastard along with the Wounded Gazelle Gambit, as the two tactics share many similarities. However, the victim of a Wounded Gazelle Gambit can be anyone (regardless of your relationship to them), be done to convince anyone (regardless of their relationship to you), and specifically involves an accusation of physical harm. In contrast, this trope hurts because it can only be used amongst those with close enough bonds that there are friends, colleagues, family, etc. that can be turned against them, explicitly invoking It's Personal. And while physical harm may be part of the narrative one constructs to ruin the reputation of their victim, anything that can make the other party look bad is up for grabs. A parent repeatedly telling their children their other parent is a bad person to turn the kids against them during an acrimonious custody battle is a Real Life version that demonstrates this.
Depending on how much of what one says are Blatant Lies versus half-truths, this is often a "high risk, high reward" ploy since it can unravel by enough people asking for (and believing in) the other side of the story. In cases in which multiple conflicting lies were told, someone comparing notes to realize something is amiss would also reveal the deception, as in a "Fawlty Towers" Plot. It's possible for the victim to find a way to clear their name and if the protagonist is the victim of this ploy, then they almost certainly will. The ensuing reveal is likely to cause those that were manipulated to turn on the one that ran the mill to begin with. If that person was well-regarded, expect there to be many a Broken Pedestal.
Sub-trope of Malicious Slander. Compare and contrast Playing the Victim Card, Frameup, Deceptive Legacy, Apple of Discord, and Convicted by Public Opinion. Often leads to We Used to Be Friends, Evil Former Friend, Formerly Friendly Family, All of the Other Reindeer, and Easily Condemned if the victim is made of Incorruptible Pure Pureness.
- Mars (1996): For most of his life, Rei was convinced his father Takayuki was a cold, unloving, father who did not care about him. When Takayuki finally makes an appearance in the story, he's awkwardly distant with Rei only because he knows how much Rei dislikes him. In reality, he's very understanding and is stern out of reasonable concern for Rei, what with Sei's suicide, Rei's mom's attempt at killing him and Sei before killing herself when the twins were young, and Rei's self-destructive tendencies and love of competitive motorbike racing. Rei comes to realize later that he first began to think of his dad as mean and cold because his mother used to tell him and Sei that all of the time when they were kids all because she was still in love with Takayuki's deceased brother Akihiko and resented being married to Takayuki.
- My-HiME: Due to the mistaken belief that Nao engages in Enjo Kosai (it's more complicated than that), and has been a bit hostile to the other known HiME, she is something of an outsider in their group. When the rules of the Festival are laid out for them by Nagi, they initially vow not to fight each other. This quickly falls apart, however, when Sister Yukariko is found, injured, and claims that Nao attacked her out of the blue. This sends Natsuki off to confront Nao about the unwarranted attack, which kickstarts the entire conflict between the girls. It would be revealed that Yukariko, acting under duress from her lover, Ishigami, lied about the attack and used her powers of illusion to fake her injuries.
- Peach Girl: One of Sae's specialties. She isolated Momo before even meeting her by spreading a rumor that Momo was absent from school due to a teen pregnancy. Sae uses this to become Momo's sole friend and ruin her life by continuously spreading rumors to support the idea she's easy and keeping Momo from getting together with her crush Toji. When her lies are eventually revealed, the whole school shuns her.
- Okami-san and her Seven Companions, both the light novel and anime adaptation. After Ryoko Ookami is nearly raped by her date Hitsujikai, he tells the rest of their school that he dumped her so that when she tries to warn them what he had done to her, none of them believe her. It is worth noting that the story opens a few years later, with Hitsujikai now the Student Council President for Onigashima High, a school for delinquents and trouble makers, and his past history completely scrubbed from the records. One wonders how many of the other girls learned Ryoko was telling the truth the hard way.
- In Miraculous Ladybug fanfiction, this became a Fandom-Specific Plot in the aftermath of the episode "Chameleon", in which a Consummate Liar bully named Lila Rossi threatens Marinette Dupain-Cheng that she will destroy all of her friendships in response to Marinette pointing out her (quite outrageous) lies.Stories with this plot often start with Lila as the Alpha Bitch, having climbed her way to the top by lying, with the rest of the class either telling Marinette to lay off Lila at best or bullying Marinette into submission at worst. Examples of this class of story include Burning Bridges, Building Confidence and Raise Your Voice Against Liars.
- Mean Girls:
- What Cady and Janis do to Regina in order to dethrone her as Alpha Bitch. While Cady doesn't really lie to Regina's friends and boyfriend about her awful behavior, Cady and Janis explicitly manipulate them using similar tactics that Regina uses to wrap the entire school around her finger and effectively Backstab The Alpha Bitch. Fittingly she replaces Regina as the new Alpha Bitch.
- In order to get back at Cady, Karen, and Gretchen, Regina inverts the trope when she places her own photo in the Burn Book and releases the entire book of rumors to the school. Not only does it act as an Apple of Discord to every social group in school, it allows Regina to play the victim and put the blame on Cady and the other Plastics, as they are the only ones not mentioned in it.
- The short story "Un Capitano Moro" from Cinthio's Hecatommithi is one of the direct inspirations for Shakespeare's Othello, however the Ensign's (Iago in Shakespeare's adaptation) motives for manipulating the Moorish Captain (Othello) are quite different. In this story, the Ensign falls in love with the Captain's wife Desdemona, but she naturally rejects him. This spurs him into planting the rumor that Desdemona is cheating on the Captain with the Corporal (Cassio) out of jealous spite and convincing the Captain of such, later aiding him in bludgeoning Desdemona to death. Othello, on the other hand, averts this trope by removing the Ensign's feelings for Desdemona and making Othello the intended victim of Iago's schemes rather than just an Unwitting Pawn.
- Curtain: Stephen Norton is a sociopath who gets his kicks out of manipulating his peers in genteel society to murder each other, allowing him to get rid of someone with no risk of detection. He does so by making an Innocently Insensitive comment at the right moment to push his victim over the edge and informing others about seeing something he actually didn't.
- Elemental Series (Kemmerer): Becca's ex-boyfriend Drew spread rumors about her getting around a lot, leading to her becoming an outcast at school and getting a lot of unwanted propositions from guys.
- The Labours of Hercules: In "The Lernean Hydra", rumors are likened to the eponymous Hydra, since it's impossible to keep down one rumor without causing more rumors to surface. In this case, a doctor is believed to have poisoned his bedridden wife to elope with his assistant (not helped by the fact that the doctor is in love with his assistant and would have gladly married her if it wasn't for the rumors). The culprit, however, is the wife's nurse, who was also in love with the doctor and thought he'd marry her if the wife was out of the way. She is vengeful against him for turning her down and used the rumors, as well as planting evidence, to frame him.
- The Railway Series: In "Dirty Work" Diesel holds a grudge against Duck, who pulled a prank on him on his first day to cease his bragging. In a more savvy case of this trope, Diesel tells rumors about the other engines to the trucks, claiming Duck had told him. As Diesel anticipated, the trucks have no qualms getting Duck in trouble and torment the other engines with using what Diesel told them. Things seem to go as planned at first, with the other engines shunning Duck as the source of their issues and the Fat Controller sending Duck off the main line to stop the arguing, but the Fat Controller catches onto Diesel's plan and later catches him in the act, this time spreading lies about Henry.
- Warrior Cats: In "Into The Wild", Tigerclaw began to spread lies about his apprentice, Ravenpaw, being a potential and likely traitor at a time when ThunderClan was under great stress. This meant that Ravenpaw couldn't easily share the truth about Tigerclaw's own treachery, and it kept him ostracized and distrusted by many of his fellow clanmates.
- Beverly Hills, 90210: Emily attempts this against her cousin Annie by telling all of Annie's friends that Annie is trashing them behind their backs. However, Annie calls Emily out on her lies and Annie's friends side with her against Emily.
- The Big Bang Theory: Played for laughs in "The Junior Professor Solution" when Amy is caught in the middle of a disagreement between her friends Penny and Bernadette. Because she missed out on normal socialization as a teenager and has heard that trash talking can increase bonds of friendship between people, Amy plays both sides of the argument and increases the negative feelings between them to feel needed and popular. Subverted when Penny and Bernadette talk it through and make up offscreen like mature adults.
- Burden of Truth: When she was a child, Joanna's father had her mentally ill mother committed and threatened to have her deported if she ever tried to contact Joanna. Joanna grew up thinking her mother had abandoned her not knowing they were being deliberately kept apart by her father and learning the truth shatters whatever respect she had for him.
- Cruel Summer: Played With. The plot of the show hinges on Kate publicly accusing Jeanette of knowingly leaving her trapped in her kidnapper's house for several months in order to steal her life. A majority of the people in the town turned against Jeanette once the accusation was made, which Jeanette herself considered as unwarranted slander, even taking the issue to court once the harassment got bad enough. The end of the season reveals that Kate was indeed mistaken about Jeanette's involvement, and the situation is resolved after Kate admits she was wrong... and then it's revealed that Jeanette actually did leave her there, just at a different moment in the timeline than Kate had claimed, making the rumors Right for the Wrong Reasons.
- Ghost Whisperer: Colleen Finn, the ghost of the week in "No Safe Place" was a victim of this at the hands of her stalker, Shane Carson. According to the detective who worked Colleen's case, Shane used lies, manipulations and harassment against Colleen's friends and family, essentially making it so that it was impossible for anyone to be close to her without having their lies turned upside down.
- Gossip Girl: After learning she has been waitlisted to Yale, Blair turns her ire against Cool Teacher Rachel Carr for giving Blair a B on an essay, and thus ruining Blair's perfect grades. After Blair's initial plan to humiliate Rachel fails, Blair uses Gossip Girl to start a rumor that Rachel is having an affair with Dan. Once again, this backfires as she is quickly discovered as the source of the lie and is expelled from Constance, ruining her chances at being accepted into Yale. But Blair persists, doubling down on her lie to her father, who pushes the issue on her behalf at the next PTA meeting. Some circumstantial evidence later and Rachel is fired from Constance while Blair is reinstated. It does not stick though, since the parents realize they don't have much evidence to back up Blair's accusations, leaving them liable to Rachel suing them for wrongful termination. Rachel is later reinstated...which sucks for her since in her panic at being fired, she and Dan made the rumor a reality by sleeping together.
- House of Anubis: Toward the end of Season 3, Sibuna was revealed to have a traitor among them in the form of a member turned into a sinner. KT was falsely accused of being said sinner, which caused the rest of Sibuna to ostracize and bully her, thanks to the machinations of Patricia—the actual sinner. Every time KT attempted to prove her innocence, Patricia would swing it back around on her and make KT seem even more guilty.
- Oz: Ryan O'Reily generally deals with his enemies by lying to any one of the various gangs in Oz that said enemy is plotting against them or framing his enemies for crimes he committed, then just sitting back and letting the gangs retaliate against the alleged slight.
- You: Joe pulls this on Candace, both in-universe and to the audience, since up until now we've only seen or heard about Candace from Joe and his hallucinations. When she shows up in season 2 and starts casually dating Forty, she tries to warn him and Love that Joe is a psychopathic Yandere, but Joe has spun the narrative that Candace, and not him, is the actual obsessive stalker in their relationship for far longer than they've known her at this point and they don't believe her.
- In the musical 13, after Evan plays matchmaker for Brett and Kendra, Brett's jealous ex-girlfriend and best friend to Kendra, Lucy, spreads a rumor that Kendra is cheating on Brett with Evan.
- The Crucible: A particularly lethal version with Abigail Williams and friends. On top of their Malicious Slander against their elders, when fellow accuser Mary Warren tries to tell the truth about their hysteria (at John Proctor's behest), Abigail orchestrates the group to turn against her and accuse her of witchcraft as well. Mary only survives by relenting and accusing John Proctor.
- The Music Man: Played with and discussed.
- Played straight with the Pick-a-Little ladies, depicted as nearly literal Gossipy Hens, who try to dissuade Harold Hill from talking to Marian Paroo by implying that she had inappropriate relations with Old Miser Madison, still bitter that he left Marian the town librarian job in his will. Subverted, since this actually makes Harold want to flirt with Marian more (the "sadder but wiser girl", after all), and downplayed, since the ladies seem to believe what they say is true, and seem truly unaware Madison was a friend of Marian's late father.
- Invoked when Harold discredits Charlie Cowell's (likely true) claims that Harold has been with hundreds of women as rumors, by claiming Charlie is just like the Pick-a-Little ladies.
Harold: But why do you think people start those rumors?
Marian: Narrow-mindedness, jealousy — jealousy mostly, I guess.
Harold: Exactly. And jealousy mostly starts rumors about travelling salesmen.
- In Yandere Simulator, one of the ways the player can eliminate one rival for her senpai's affection is to start a vicious rumor mill causing said rival to being bullied, and rejected by Senpai (and if their reputation is low enough, will commit suicide).
- Manga Soprano: Shiho makes one by making Ram look like a violent bully after being called out for stealing her fiance Kinoshita-kun, which leads to the latter getting transferred. After the man was fired for selling secrets for a rival company, Shiho attempts to do this again by requesting Chief Kairi to be transferred, even attempting to steal him from Ram. However, Kairi is not impressed and her mill turns against her as a result.
- Alfred J. Kwak: Dolf and Alfred end up at the bottom of a well during the winter, because Alfred spooked Dolf and then fell in himself while trying to get Dolf out. Later on, they're almost eaten by Krabnagel the cat. After they're rescued, Dolf tells all his friends that Alfred deliberately pushed him in. They treat Alfred with hostility afterwards, which Alfred does not realize since Dolf greets him like a friend.
- Big Mouth: In Season 5, Missy gets angry at Jessi and Ali for upstaging Missy at a protest she started. After being consumed by hate, Missy anonymously spreads a rumor online that Ali cheated on her girlfriend with Jessi, turning everyone against them and prompting Ali to fight Missy physically.
- Thomas & Friends: In "A Most Singular Engine", after getting snubbed by the vain Daisy, Diesel spreads rumours between her and Harvey that they have both been bragging about how they're more unique and special than the other. He is left indignant when his plan backfires and rather than clashing, the two end up becoming friends.