It's not that difficult for a character in a work to jump to conclusions. They might believe that they're a certain trope, that a different character is a certain trope, or at least that a certain trope is happening around them. But it turns out that they are very much wrong. And unfortunately, it will often take them until the end of the story to realize their mistake. In a Darker and Edgier story, they might not even realize the truth until it's too late for them to get a Happy Ending. In a Lighter and Softer story, only the villain will really be a victim to this and meet his/her downfall.
Some tropes in the The Wannabe Index (like Big Bad Wannabe, Casanova Wannabe, Prince Charming Wannabe etc) and Mistaken for Index are sub-tropes of this trope. There can be overlaps with Entertainingly Wrong, Hidden Depths, Horrible Judge of Character, Idiot Ball, One Dialogue, Two Conversations, and More than Meets the Eye as well. Compare also with Wrong Genre Savvy, where a character acts as if they're in a different genre than what they really are. Compare Tragic Mistake.
- DuckTales has two examples during the story "The Once and Future Warlock":
- Launchpad assumes that Laird's influence on Doofus (who he's brainwashed) won't cause the young duck to make any moves against him, given that Doofus is a friend and fan of his. This nearly gets him zapped.
- In the same story, Scrooge and the boys assume that Laird's brainwashing has completely wiped away Doofus' real personality. They're wrong, and the real Doofus is ultimately saved.
- In The Flash, Hunter Zolomon in his persona of Zoom is convinced that he's a Stealth Mentor / Anti-Villain that helps heroes grow stronger by making them experience personal tragedies. In truth, he's delusional to the point where he qualifies as legitimately mentally ill, and is as much a danger to heroes as any fullblown villain is.
- Deadpool: In Operation Annihilation, when the Hulk assumes that Deadpool is attacking him, and that he was hired by somebody to provoke him into a trap. In truth, Deadpool is acting on his own trying to provoke the Hulk into killing him, but even when he tells Hulk that nobody hired him, the Hulk still assumes it's part of some more elaborate scheme. Later in the same story, some somewhat smart soldiers see the Hulk rampaging and guess that Deadpool is the cause of it. They guess right, but when they see Deadpool in a bus full of children, they assume he's taken them hostage, when he was actually trying to rescue them.
- In a Judge Dredd comic, a perp tries to escape from Dredd by jumping into what he assumes to be a laundry chute, but ends up being a waste disposal unit.
- In many Superman comics (especially Lex Luthor: Man of Steel), Lex Luthor thinks (or says he thinks) that he's The Hero and the Only Sane Man to most of humanity (who insist on putting their faith in a powerful, dangerous alien) and that Superman is a Villain with Good Publicity. Of course, the reality is that Lex is a jealous villain and that Superman is an Innocent Alien and All-Loving Hero.
- In Red Daughter of Krypton Lobo taunted Supergirl during their whole fight, thinking that she'd fight sloppily if she got angry. It turned out that blind rage makes her more dangerous instead of more ineffective.
- During the events of Superman: Doomed, Supergirl, who was using her anger to protect the galaxy, assumes Superman's just "getting in touch with his angry side" and can use his SuperDoom form for good. So she goaded him... and it made things worse.
- Tales to Astonish: In issue #59, when Bruce Banner goes missing shortly before the Hulk is seen in the area, Betty Ross, Giant Man and the Wasp go searching and find an trashed jeep with Bruce's shredded clothes in it. They presume this to mean the Hulk has attacked and abducted Banner, because they don't know one or two little details about the good doctor.
- In Watchmen, after discovering that the recently murdered Edward Blake was actually the Comedian, Rorschach assumes that a "mask killer" is targeting ex-costumed heroes and is seemingly proven right when an assassin attacks Adrian Veidt. Blake was actually killed for knowing too much by Veidt himself, who then staged the attempt on his life to keep Rorschach on the wrong track.
- In X-Men, this happened when they had to deal with Dracula. Yes, using a cross on Drac is a good way to keep him back. But, it really doesn't work unless you have the faith behind it, which the very Jewish Kitty Pryde and the oh-so-unrepentant Wolverine find out. Luckily for the former, her Star of David necklace is equally effective as a cross at repelling Drac.
- In Frozen, everyone assumes that the "act of true love" needed as a Curse Escape Clause is True Love's Kiss, but it's not romantic love that ends up breaking the curse in the end, but sisterly love. What's more, the act isn't done for Anna, but by Anna, to keep Elsa from being killed by Prince Hans.
- In Beauty and the Beast, Gaston (Big Bad) thinks he's the hero and that Beast (Jerk with a Heart of Gold) is a monster, who wants to get his claws on Belle. But in the end, it is clear that the opposite was true.
- In Kung Fu Panda, Tai Lung grew up thinking he would be The Hero instead of the Big Bad. In fact, the entire story is a stereotypical action Hero's Journey when seen from his perspective. Set up to become The Chosen One, he is betrayed by his mentor, and spends a long time in captivity. Then he breaks out of the predicament they put him in. He overcomes obstacles and beats up a whole lot of Mooks led by The Brute; then he beats up a Quirky Miniboss Squad led by his counterpart/Shadow Archetype by revealing an 11th-Hour Superpower he developed after his initial defeat; then he beats up the Big Bad, who was responsible for the things that happened to him at the beginning; then the Dragon Ascendant powered by an Artifact of Doom is revealed as the True Final Boss, He manages to wrest control of the artifact from the Dragon Ascendant, prepares to use it, and... his story crumbles around him, because he does not have what it takes to be The Hero. The Dragon Warrior title he wanted so badly brings nothing with it. Being a true Dragon Warrior requires understanding that there isn't anything that can make you special beyond your own effort. His design also includes a Stealth Pun on the topic. According to creator commentary, the color gold throughout the film symbolizes heroism. The only gold in Tai Lung's design is his eyes, because he's only a hero is his own eyes.
- In Megamind, Megamind thinks that Hal will be the perfect person to train as a hero once he's seen him: he thinks he's a complete nobody who can realize his true heroic potential with his help. Unfortunately, Hal fits a different set of tropes...
- Two wrongful assumptions are made in Sinbad: Legend of the Seven Seas by DreamWorks Animation: 1) the tribune of Syracuse is certain that the pirate Sinbad is responsible for the theft of the Book of Peace. Sinbad's boyhood friend Proteus defies this assumption, and puts himself in Sinbad's place on Death Row to allow Sinbad to recover the MacGuffin. 2) Eris, the goddess of discord, presumes Sinbad to be such a vain, selfish brigand that she wagers the Book of Peace that Sinbad would not likewise forfeit his life to save Proteus. Both the tribune and Eris are proven patently wrong, because Sinbad is really a Jerk with a Heart of Gold.
- In Starship Troopers: Invasion, Ice Blonde is just as surprised as the audience is about who survives the film. She survives the film, of course. She's surprised Mech survives, completely inverting Black Dude Dies First, and likewise Ratzass averts Big Guy Fatality Syndrome. Trig dies, as does Bugspray, and the not-so aptly named Hero.
- The Sword in the Stone: The little girl squirrel who upon meeting Arthur in squirrel form, desire to have him for a mate, much to his annoyance. She assumes the reason he isn't falling in love with her as fast she did for him is just shy and playing hard to get, and thus continues to get close to him to get him to accept her. When she finds out he's a human, and likely realizing he didn't have any interest or attraction to her, it broke her little heart.
- In The Boxtrolls, Mr. Trout and Mr. Pickles are convinced they're the good guys fighting the forces of evil, but as the movie goes along they begin to doubt this perspective.
- In The Princess and the Frog, Naveen mistakenly thinks that being kissed by Tiana will turn him back to a human. Later, he accuses her of falsely wearing the tiara, deceiving him into thinking she was a princess . They turn back into humans after they get married, as Tiana has really become a princess then through her marriage to Naveen.
- In Zootopia, Judy jumps to the conclusion that the Timber Wolf mercenaries that have been capturing the missing mammals as they go savage are the "Night Howlers" that Mr. Otterton was yelling about. Turns out she was mistaken and later learns that Night Howlers are the nickname of a flower being used to create the Chemically-Induced Insanity turning predator animals savage.
- At one point in Babe, Farmer Hoggett believes Babe to be a sheep-killer, because he found one of his ewes lying dead in his pasture with a gaping wound, and fresh blood on Babe's snout. Hoggett takes Babe to the barn and prepares his shotgun to terminate the killer pig. Fortunately, Hoggett's wife announces that local police are seeking armed sheep rustlers in the area. She then notices her husband cradling his shotgun.
Esme Hoggett: What on Earth are you doing with that gun?
Farmer Hoggett: Oh! [looks at firearm, befuddled] Nothin'.
Esme Hoggett: [rolls eyes and waddles away]
- The Crocodile Hunter: Collision Course: When the agents find the Irwins' truck, one of them picks up the container on the seat, thinking it's takeout. He learns otherwise when he releases the bird-eating spider.
- Desperados (2020): After Jared seemingly disappears from Wesley's life after they slept together, she and her friends assume he's ghosting her and send him a elaborate hate email while drunk. But it turns out he was in a car accident instead, causing Wesley to freak out about the e-mail.
- In Doom, Sarge thinks that he's The Hero and main character when it's actually Reaper. At one point, he even says "I'm not supposed to die!" when he's dragged off by a monster. He ultimately turns out to be the villain of the movie and Final Boss.
- In Enchanted, talks with her young friend Morgan, who is nervous about her father marrying Nancy, having read plenty of stories involving a Wicked Stepmother. Giselle assures her that most stepmothers are actually very nice people, a true lesson, that proves its worth when Giselle becomes Morgan's stepmother. Unfortunately, Giselle uses her own stepmother-to-be Narissa as an example, unaware that Narissa actually is a wicked stepmother who is trying to kill her.
- Fish Tank: Mia practices her dance moves in the hopes of landing an audition. She does not realize the audition she is preparing for is meant for exotic dancers, only learning this at the audition itself. Conor, her momís boyfriend, also turns out not to be a single man as Mia and her mother believed.
- The Fugitive:
- Almost everyone believes that Doctor Kimble murdered his wife, especially the jury at his trial. They heard the recorded 9-1-1 call, with the dispatcher asking the victim if anyone else is there, and the distinct reply, "Richard, he's trying to kill me!" Surely, this was deathbed testimony as to her killer; in fact, it was a warning to Kimble that the murderer was still loose in their home. The most unswayable character is federal marshal Sam Gerard, who is determined to stuff the escaped Kimble back into prison or into a grave.
- When Kimble escapes through the storm drains and comes to a point where they bisect, he tosses his jacket down one tunnel and goes down the other one. The pursuing US Marshals aren't fooled for a second, they simply split up in order to check both passages. Later, when calling his lawyer, Kimble lies and says he's in St. Louis, correctly suspecting that the cops might be eavesdropping, but not that their equipment would determine that Kimble's in Chicago.
- In Iron Man 3, Tony deduces that Aldrich Killian is selling the Flawed Prototype Extremis technology to the Mandarin to use in suicide bombings. Considering that this is almost exactly how his antagonists teamed up in the previous two Iron Man films (the Ten Rings and Obadiah Stane with the prototype Iron Man suit, and Whiplash and Justin Hammer with Whiplash's arc reactor), he'd be forgiven for jumping to that conclusion. However his assumption is wrong: the "bombings" are all accidental and Killian used the Mandarin (not the real one, but a fake one) as a scapegoat to explain them, leading to a plan to overthrow the President of the United States and install a puppet to in effect control both sides of the War on Terror.
- My Name is Bruce has this from two angles: Jeff kidnaps Bruce Campbell, expecting him to be a real-life badass like Ash, and hoping that he can cure Gold Lick's monster problem. Bruce, on the other hand, is oblivious to the horror because he thinks that the whole thing's a prank.
- In Outlander, the priest mistakes the moorwen for a demon and tries to exorcise it. The moorwren mauls him in the middle of his chant.
- In Pirates of the Caribbean: The Curse of the Black Pearl, Elizabeth thinks Barbossa's crew are standard pilfer-and-loot pirates who would hold her for ransom if they found out she's the Governor's daughter, so she gives them a false last name: Turner (the last name of her secret love, and probably the first name to pop into her head). Unfortunately, they're not after something so mundane as money; in fact, one of the things they're looking for is a kid about her age with the last name of Turner. Oops. She also expects pirates to honor the Code of the Brethren as if it were a binding rule of law, not realizing that Barbossa is a Rules Lawyer who sees the Code more as "guidelines."
- In Star Trek (2009), the "new" Kirk assumes that a Romulan from The Future would know what the Enterprise crew will do, so they should be unpredictable. His Vulcan shipmate more accurately recognizes that the Romulan and his ship are a Timeline-Altering MacGuffin, causing a new chain of events (though nonetheless failing to prevent the assemblage of the same Enterprise crew). Later, old-Spock takes advantage of Kirk's ignorance to falsely "imply" that Never the Selves Shall Meet is a rule of this particular Timey-Wimey Ball.
- In Troy, Paris believes that The Power of Love can motivate him to defeat Menelaus in a duel. The old but incredibly strong and experienced warrior beats the shit out of him.
- In "History, Herstory, Bearstory" from Bear in the Big Blue House, Jeremiah Tortoise tells Bear, Ojo and Tutter the story of his Great Grandfather Hephaestus Tortoise, who founded Woodland Valley over 200 years ago and who owned the old house that they found. They are so inspired that they go back and tell Treelo, Pip and Pop about it, then decide to install a dedication plaque at the old house. Jeremiah is touched, then states that he can't wait to tell Hephaestus about it when he gets back. Given everyone's reactions, they clearly assumed that Hephaestus was dead.
- After the protagonist of Double Homework sees Tamara for the first time since retreating to his room after the avalanche, the awkward nature of the encounter makes him think Tamara hates him. Little does he know what she's after....
- The title character of Melody avoids seeing or talking to the protagonist for a few days after she sees Bethany in his apartment, thinking that thereís still something going on between the two exes. Bethany does everything to further this assumption, referring to herself as his fiancée rather than his ex. Itís only an intervention from Sophia that keeps the two of them from drifting entirely apart.
- CK of Commander Kitty believes himself to be The Hero and Ace is The Rival. Of course, Ace turns out to be a genuine Nice Guy with no ill will towards CK at all.
- Darths & Droids: Corey falls for a form of it when he reaches Dagobah in the The Empire Strikes Back arc. He goes in with no active sensors to avoid detection by the native population (for security reasons, assuming they're all Imperials). This leads to him faceplanting in a swamp because he couldn't tell what kind of planet he was actually landing on (he thought the fog was smog).
- In El Goonish Shive, Magus, the Mirror Universe counterpart of Ellen, is convinced that Ellen is a trans man just like him, and is simply being forced to hide her feelings of dysphoria. In a conversation with Elliot later on, Ellen explains how Magus may have reached that conclusion based on misinterpreting and projecting onto her Cloning Blues from earlier in the series, and sets the record straight by pointing out there is nothing stopping her from using magic to change her sex if she actually wanted to.
- Fire Emblem Heroes: A Day in the Life:
- In Chapter 18, Xander catches wind of the fact that a number of women in the army have been complaining about someone harassing them. Assuming that it must be his womanizing retainer Laslow, he marches off to lecture him again... only to find that it was actually Gray who was harassing the girls, and Laslow's been on his best behavior.
- In Chapter 78, Mikoto gives her granddaughter Kana a closed envelope as a gift, telling her if she's going to eat delicious food, she can use this. Kana's father, Corrin, assumes that Mikoto just gave her money and is spoiling her. When he get his hands on the gift and opens it, however, he finds out that Mikoto just gave her chopsticks. Despite this misunderstanding, he is happy about this and goes out with his daughter to eat.
- Girl Genius:
- Ottvar Tryggvassen, Gentleman Adventurer, is convinced that he's the leading man, Baron Wulfenbach and Gil Wulfenbach are the diabolical mastermind and the mastermind's fiendish right hand man respectively, and Agatha Clay is the leading man's beautiful young sidekick (even if she's not the Mad Scientist's Beautiful Daughter like he originally thought). Unfortunately he's completely insane and doesn't realise that he's wrong on all counts, so his plans are almost always inappropriate.
- Once he realizes that Agatha is a Heterodyne, he changes on the last part and treats her as the Hero of Another Story (possibly with himself as some manner of Mentor Archetype) — which doesn't solve his problem, since he's still completely insane, and Agatha knows it and wants nothing to do with him. Word of God is that he's re-cast his delusion slightly, Agatha is now the tragic love interest (he's going to kill her last, in some sort of love-suicide pact).
- One of the radio plays questioned whether Othar really is delusional — after all, having Sparks in charge has been almost always catastrophic for common Europeans, and it's not at all clear that the heroes will be able to break that cycle.
- The Order of the Stick:
- Elan gets this sometimes. For example, the first time they defeated Xykon he activates a Self-Destruct Mechanism in order to invoke a Load-Bearing Boss situation. And then won't escape the castle until the last possible second to be more dramatic. On another occasion he correctly predicts the current villain will try the old abduct-the-love-interest ploy...but doesn't realize that he's the abductee
- Tarquin appears to have cast himself as the Big Bad and Elan as The Hero, unaware that it's Xykon and Roy respectively. Eventually Elan crushingly tells him that he's "not the real villain", and lets him drop off an airship, refusing to confront him in the epic showdown Tarquin wants. It is implied that Tarquin would be quite content being killed by Elan in a battle (the hero always defeats the villain, after all) but the anticlimax of being left in the desert causes him to lose both the plot and his cool, and he's left shouting "This is a terrible ending!" at his retreating son.
- Sluggy Freelance:
- Commander Clown and his allies think he's the good guy. While that's standard for a Well-Intentioned Extremist, it's not usually discussed in such a meta fashion.
Torg: He's hanging from a helicopter's rope ladder while laughing maniacally and triggering explosives.
Dart: OK, that sounds a little bad-guy-ish.
Torg: It'd be OK if he said something witty, but the laughter pegs him.
- In "The Sci-Fi Adventure", the otherwise-nameless Captain of a starship believes he'll be the sole survivor of an alien rampage because he's the "handsome masculine lead", but Torg questions the logic he used to reach that conclusion, calling him a "shallow, one-dimensional stereotype" and suggesting that Riff and Torg will be the sole survivors instead because they have the more interesting backstory. The captain shouts "What is this? A sci-fi thriller or a goofy buddy movie?" The alien promptly answers his question.
- Commander Clown and his allies think he's the good guy. While that's standard for a Well-Intentioned Extremist, it's not usually discussed in such a meta fashion.
- Swords: In this strip, a troll invites an adventurer to take one sword from his collection, but warns that many of the swords are enchanted with terrible curses. The adventurer assumes this is a Secret Test of Character to see if he if greedy enough to choose the flashiest-looking sword out of the collection, which is guaranteed to result in Death by Materialism or worse. He instead picks up a humble wooden sword thinking it's safe... only for his arm to turn wooden as well, much to the troll's amusement.
Troll: *snort* It wasn't a test, you dumb idiot.
[The Adventurer's whole arm is now a tree]
Adventurer: Oh... Is it too late to pick again?
- The TV Tropes page on Rick Astley plays on the expectation that the link to "Never Gonna Give You Up" will lead to the expected Rickroll. Instead, it links to a Chinese song. The real link is listed with the rest of his music videos.
- In Atop the Fourth Wall, Linkara in one of his Comic Book Quickies episodes assumes that reading a text box that says the location of a story is the world's largest flea market, that the giant flea in the panel is the world's largest flea and assumes that the comic's creator doesn't know what a flea market is. The real answer he found was much more, surreal. The flea is the the giant flea market eating flea. He reacts pretty the much the same way as the audience.
- Ten Little Roosters:
- Adam teams up with Gavin, only to find out Gavin's clone (long story) is in trouble. Gavin and the clone die horribly by mousetraps. When Barbara confronts Adam and suggests they team up, Adam refuses because of what happened. The killer is later able to ambush him and strangle him to death.
- Miles believes that he can be the hero of the story by dressing up as Ruby Rose and trying to think like her. Even more he believes that beating Skyrim eight times and getting all of the Chaos Emeralds makes him even more suitable for surviving. It doesn't. At all. The one time he tries to take action, fighting a puma, he freaks, drops his weapon and runs.
- In this ''Swedish Chef'' YouTube video, two talking pumpkins try to use Briar Patching, advising the Chef to use increasingly bizarre/dangerous implements to smash them, on the assumption that he won't have them. However, this is the Swedish Chef we're talking about, who can always pull a sizable arsenal out of hammerspace.