- A Crown of Stars: In chapter 1 future Asuka said her six-months-younger counterpart that she will tell Shinji —after kissing him- why she ran to the bathroom after their First Kiss. Asuka did not want to believe it, but many chapters later it happens. In chapter 26 Asuka remembers how she refused believing a prophecy straight of her future self.Wow. And two days later, here we are. Wow... I even told myself it was going to happen, and I still couldnt believe it.
- Once More with Feeling: Fully knowing how it went the previous time, Shinji tries to point out the obvious risks in the mission for capturing the 8th Angel. This prompts Asuka (who was mad at him at the time for unrelated reasons) to laugh in his face and go along with it anyway. Of course, when the mission goes awry the way he predicted and Asuka nearly ends up killed as a result, she feels guilty for dismissing him so lightly.
- In the Bleach fic The Black Wrangler, most of Ichigo's friends believe he simply imagined the Title Character.
- Two instances in the Touken Ranbu/Onmyōji crossover The First Saniwa:
- Izuminokami overhears two yōkai discussing their plans to Kill All Humans, but is dismissed by Kasen as "hallucinations". Cue next chapter with Aoandon declaring her intention to free demonkind by wiping out humanity.
- Ishikirimaru warns Heian-kyō folks of high amounts of malicious energy that he senses, but everyone dismisses his concern since Yamata-no-orochi is already defeated at this point.
- Shows up a few times in My Little Pony: Friendship Is Magic fan fiction.
- The Writing on the Wall has the eponymous writing on the wall of an ancient structure, which is disregarded as a curse intended to scare off tomb robbers. It is intended to scare people off, but it isn't a curse, but a warning of the danger it was built to contain.
- I Have This Friend... is built around this trope, as Celestia does not believe Twilight is talking about somepony else.
- Justice League of Equestria:
- Mare of Steel: When Rainbow Dash, suffering from lack of control of her new powers, accidentally shatters one of Applejack's trees with a kick, AJ doesn't believe her when she tells the truth. Later, when Rainbow Dash reveals her identity as Supermare to her friends, Applejack and Rarity don't believe her... until Rainbow Dash blows up a boulder with her heat vision to prove it.
- In Brightest Day, In Blackest Night: When Shining Armor tries to tell Cadence about his recruitment by the Green Lantern Corps, she laughs it off as a joke. This in spite of the fact that she's had lunch with an alien superhero and is best friends with a demigoddess — something she herself reminds Shining of when reassuring him that she'll believe him no matter what.
- The Twilight Child: Frustrated in her attempts to figure out who exactly 'Midday Eclipse' is, Rainbow Dash asks her. In response, Midday tells the her the absolute truth. Much like the Superman example (see Western Animation) Rainbow Dash thinks she's being played with. Averted with the Cutie Mark Crusaders nearby, who due to previous events realise Midday is telling the truth.
- The Pandoraverse: Chakra Blossom, after shaping up and abandoning his old manipulative and selfish ways, is the only one to catch on to the fact that Moondancer was responsible from Midnight Abyss' death and is playing her grieving mothers for fools. Starlight thinks he's just throwing accusations at a dear family friend and throws him out of the house. When he was genuinely telling the truth and trying to help, his record as an extremely manipulative and untrustworthy stallion ended up ruining everything.
- Loved And Lost, an extended retelling of A Canterlot Wedding, has the canonical example of Twilight's suspicions regarding the false Princess Cadance. In a twist of irony, the ponies who didn't believe her — Shining Armor, Princess Celestia, the Mane Five and Spike — get one of their own after Prince Jewelius turns them into hated pariahs for failing to prevent the Changeling invasion. After they learn that Jewelius himself helped Queen Chrysalis to infiltrate Canterlot and then double-crossed her to steal the throne, they try to tell this to Twilight and Canterlot's citizens, but they refuse to listen to them while Jewelius has them wrapped around his hoof.
- In the Jackie Chan Adventures and W.I.T.C.H. crossover fanfic Kage (part of Project Dark Jade), Jade's claims of not being a threat are this, especially after a takeover attempt by the Queen and a dose of Blatant Lies from Nerissa (as "the Mage").
- Inverted in a running gag throughout Dungeon Keeper Ami, Mercury's repeated attempts to explain that she is NOT a depraved rapist- despite this, the fact that all the stories regarding her exploits in battle are, in fact, true, sabotages her -the rumor mill never lets her catch a break.
- This is the basic premise of The Boy Who Cried Yuri, with Shinji on the receiving end. When he tries to alert Misato, she instantly dismisses him — even though she should know very well that he's too much of a coward to make this up. Asuka even lampshades it.Rei: Asuka, do you think it is wise to do this now? Shinji may come in at any time.
Asuka: No, Misato was talking to him. He's probably gotta go apologize to Fuyutsuki for screwing the test up.
Rei: Do you think he suspects something?
Asuka: I doubt it. Even if he does, people will think he's just fantasizing like he always does. The little pervert.
(unknown to them, Shinji's already hiding in the room with a tape recorder)
- And then it gets double subverted when Shinji shows his audio evidence to Misato: she ambushes the girls during their next session... and instead of punishing them, she joins the fun.
- In Kyon: Big Damn Hero, Kyon's sister had tried to tell her parents and friends that her brother is a hero and has real adventures but nobody believes her. This is in part because her brother, knowing she can't keep a secret, tells her enough to know but not enough for her to be believed if she tells someone else.
- Lampshaded in When in Doubt, Obliviate. After Gilderoy Lockhart complains that Sirius believes Lockhart erased his memory before taking him to St. Mungo's that fateful Halloween night, Harry comments that it's the truth.Lockhart: That just makes it worse. Still, at least no one else seems to believe it.
Harry: I think it's the way he's phrasing it, really. It makes him sound like it's just a conspiracy theory.
Lockhart: I've never tried the whole Cassandra Truth but it's really working for me.
- In the Ranma ½/Rosario + Vampire crossover Big Human on Campus, Ranma will tell anyone at Youkai Academy who asks him what kind of monster he is that he's a human (which he is). However, only Tsukune and Moka believe him.
- Neither of Calvin's parents believe him when he describes the bizarre adventures he's been on in Calvin and Hobbes: The Series.
- Same with Miss Wormwood when grading his paper on Egypt (which he completed by going there himself).
- A Hero: "I AM AN IM-PER-I-A-LIS-TIC SPACE NATZI."
- In Harry Potter and the Descent Into Darkness, a Dark!Harry fic, when picking Harry's "treasure" for the Second Task of the Tri-Wizard Tournament the cup comes up blank when picking a hostage for Harry to save. Everyone assumes the cup is malfunctioning. No one considers that maybe there's no one at Hogwarts that Harry gives a damn about anymore. Also in Divination class Ron scrys that Harry is a manipulative liar and a murderer but immediately dismisses it as having misread the results.
- In the Death Note Slash Fic Fever Dreams when Light goes to the media, L manipulates the media in order to suppress Light's story: painting his "Kira experience" and claims of having met the real L in the same light as someone claiming to have had a demonic possession and an Elvis sighting so that no one will ever believe him. There's also the instance when Light is cornered and L has all but proved that he is Kira, Light counters with the argument that if he really was Kira then why were they all still alive and why would he allow himself to be trapped so easily? Aizawa suggests that Kira might just be "a Fool for Love" but L immediately dismisses that idea as ridiculous — Kira would never fall in love with L!
- Invoked by Hobbes in Can You Imagine That?, setting a Forget-O-Ray on everyone but himself and Calvin for this reaction.
- In Apollo Justice: Ace Attorney fanfic Dirty Sympathy Daryan screams at the Detention Center and at his trial that he wasn't guilty of the murder he was accused of and that he was framed. No one believes him.
- The Big Bad weaponizes it in The Measure of a Titan. The OC David foster is completely honest about what he knows of his history and his ignorance of why people are after him, but things are arranged by the Big Bad to make him look like The Mole to Raven, sowing dissent.
- The Sassgardian in Superhero RPF has a lot of headcanons, as the other fanfic writers put it, to share from the anatomy and mating habits of dragons to Asgardian culture. Most, if not all, of it is true. When they begin to believe him this quickly turns into a case of Too Much Information.
- In Make a Wish there's an entire magical family descended from the mythical Cassandra, all of whom have inherited the same curse. Instead of going mad as no one pays attention to their predictions, they use what they see to start profitable businesses, with a sideline of helping the good guys (in the story, Harry Potter).
- In Sonic X: Dark Chaos:
- In The Witch of the Everfree, Twilight manages to predict both Nightmare Moon and Discord's returns before they happen, but Sunset doesn't take her seriously, assuming that if they were actual threats Celestia would be doing something about them.
- In second story of Cinderjuice, The Bug Princess, there is an amusing example of this. One of Lydia's dorm mates, Tara, is certain that Lydia is bringing an unregistered male visitor into her room. However, when said male visitor is a shapeshifter, this is difficult to prove.
- The Second Try: When Gendo confronts Shinji about his conversation with Asuka during the attack by the 15th Angel, Shinji tells him exactly what's going on. Gendo promptly dismisses his son's warnings as the ravings of a mad child because he refuses to believe that he'll never see his wife again.
- Corrin Reacts: Takumi is heavily insistent that Corrin is the prankster that Ryoma and Xander are hunting for. However, all of them dismiss him as being overly paranoid.
- A Certain Unknown Level 0: No one in MINUS believes that Touma is the Unknown Level 0 when he tells them upfront because they can't believe he didn't fight Accelerator to make himself strong.
- In Snapped Draco makes several attempts to alert Snape to Harry's rule-breaking activities, only to be dismissed as lying to try to get Harry in trouble.
- Happens in a number of Miraculous Ladybug fics spawned by the same tumblr prompt. The specifics vary depending on the author, but the gist is that Marinette finds out Adrien is Chat Noir and decides to tell him that she knows, that she is Ladybug and that she has a crush on him. Unfortunately, she manages to fumble it so badly that when she actually tells him she's Ladybug, he assumes she's lying. And Marinette is then further humiliated when Chloe hears the conversation and brings it up in front of the class.
- In the fourth chapter of Royal Blue and La Sylphide, Paulette, the little girl Gabriel is babysitting, remembers getting turned into a mermaid champion by La Sylphide to fight a Spectre in detail. Fortunately, her story about "a prince with blue feathers and a fairy princess" is waved away by her parents as a game of make-believe.
- In Weight of the World Team RWBY refuses to believe Emerald was the one who attempted to pickpocket America when he and Canada arrived in Vale, dismissing America's claim as soon as he brought it up. This results in the brothers not sharing their discovery that Emerald has a hallucination Semblance with them or JNPR. In contrast, when America tells Penny about the Semblance and Emerald and her team's untrustworthiness, she believes him immediately.
- In The Changeling Sequence, Tim Drake tries to comfort Dick by exposing his theory about Jason secretly coming back from the grave. He only manages to upset the older hero because hey, dead generally stays dead.
- A lighter example would be people cooing over Damian when he casually declares his dad is Batman. Every little kid believes their father is a superhero, after all.
- SAO: Mother's Reconciliation: It's established early on that Kouichirou saw Sugou's true nature from the very beginning, and warned his parents repeatedly not to trust him. Sadly, neither Shouzou nor Kyouko listened, and Asuna and 300 other SAO survivors ended up paying the price.
- Duchess overhears Raven and Apple admit that their relationship is fake in Girlfrenemies. She tries to out them but no one believes her. Apple and Raven are too obviously in love to be faking. After Apple and Raven begin dating for real, Apple outright tells Duchess that no one will believe her story that they weren't really dating until a few minutes prior.
- The New Adventures of Invader Zim has the canonical example of absolutely no one believing Dib about Zim, and later the other Irkens, being aliens. For a separate example, starting in Season 2, there's Tak's insistence that Zim is the mystery masked figure "Miz" who is inciting rebellion against the Tallest. No one believes her about this, due to a combination of thinking Zim wouldn't use such an obvious alias (and that he lacks the charisma to pull it off) and viewing Tak's belief as just an extension of her obsession for revenge on Zim.
- In Amazing Fantasy, Izuku suddenly manifests spider powers after nearly dying from a spider bite. He tries to pass this off as just getting his long-awaited Quirk, but this infuriates Bakugou, who believes that Izuku was hiding his powers for years despite Izuku's assurances otherwise.
- Downplayed in Boldores And Boomsticks. Many characters assume that Yang's performance at a fighting-type tournament is complete nonsense, given that she's a human who supposedly beat many pokemon. Yang repeatedly proves the doubters wrong, either with photographic evidence or outright demonstrating her skills.
- Also downplayed with Professor Cypress. As hysterical as he can be, Professor Oak knows he can be right as often as he's wrong, and the times he was right have turned out to be pretty serious(like those incidents with the "Water's Great Guardian" and the Unown). So when he starts trying to warn Oak about the Grimm, he actually takes it seriously as something is probably happening, and if Cypress is right, lives could be at stake.
- Wander Over Foster's AU One-shot (Wander over Yonder, Foster's Home for Imaginary Friends): No one believes Bloo when he says that Wander is an alien. Unlike his other conspiracy theories, this one is true.
- A Starstruck Phantasmic Romance: A mall guard, upon looking at how skinny Starfire is and not knowing about her powers, refuses to believe she hurt Dash.note
- So Rot Vie Blut: The man who poisoned the king tries to tell Grimhilde that Snow White was behind it, but Grimhilde doesn't believe him.
- In The Fall of Professor Arc, everyone Roman tries to tell about Jaune refuses to believe that some kid with no skills at anything could masquerade as a competent professor under the noses of the entirety of Beacon.
Cassandra Truth / Fan Works