We please the fleeting guest,
And deal full many a thoughtless blow
To those who love us best"
Some heroes and heroines can take a huge amount of trouble and danger in their stride. Big Bad out to get them? Yesterday's news. Death Traps to the left and right of them? Snore. The End of the World as We Know It? They already know, thanks, and they're working on it. These characters know that a burden rests on their shoulders and don't let it get them down.
There's only one thing that can bring a seemingly invincible character to their knees: Betrayal.
It doesn't have to be anything as dramatic as switching sides or selling out to the Big Bad. If one makes a few scathing comments about their leadership skills, or another holds the hero responsible for his Cynicism Catalyst, the results can be as devastating as though they'd painted a target on their pal's head and handed out sniper rifles.
Can be played for comedy if their reaction is clearly an overreaction — surviving a cave in, an ambush, and a death trap without breaking a sweat, only to burst out into tears when his girlfriend forgets his birthday, for example. Generally it's anything but funny; most people can relate to having someone important let them down. Even if it's an overreaction it may reveal exactly how much stress the character is under.
A second version of this trope is where the hero has already given their buddy a second chance, overlooking past (or even current) misdeeds in the interest of preserving the friendship and deciding to accept their pal just the way they are, warts and all... as long as their misdemeanors are confined to people who aren't the hero or their immediate family. Should that unspoken truce be broken, a massive Freak Out! is only seconds away.
A third version of this trope comes when the hero or the villain develops a bond with someone, only to discover that the person in question was never his friend, and just pretended to be one. Often followed by the obvious next question, Was It All a Lie?
This is, of course, Truth in Television — the vast majority of us care far more about what our parents, friends, and family think than what Joe Bloggs down the street may say about us.
Particularly brutal if the victim is betrayed by the ones who supposedly rescued him from a Friendless Background, or if they desperately seek friendship above all else. A Sadistic Choice, Break His Heart to Save Him or Because You Can Cope excuse may be made if the victim's "betrayer" felt as though they had no choice but to abandon them. If the characters in question were friends with each other prior to the betrayal, it probably triggers FaceHeel Turn, Evil Former Friend and We Used to Be Friends. Compare and contrast Plot-Mandated Friendship Failure, where the friend merely leaves rather than outright betrays him. Betrayal by Offspring is similar except that the betrayal is done by a character's son or daughter.
- In End of Evangelion, this is done twice (at least). In the past, when the first Dr. Naoko Akagi becomes the lover of Gendo Ikari, he instead callously betrays her by making a clone of his dead wife and makes it clear that she is not needed anymore. Heartbroken and enraged, she strangles the clone and then commits suicide by throwing herself from the control balcony. Years later, Dr. Ritsuko Akagi becomes another lover of Gendo, but she has rigged the MAGI computers to blow in hopes of killing Gendo in a Roaring Rampage of Revenge for both Akagis, only for her mother (in the programming of the MAGI system) to disable the bomb. Ritsuko is understandably devastated by this betrayal. Then, she is shot by Gendo. Yeesh, as if this show wasn't dark enough...
- Sasuke Uchiha of Naruto has reduced many a protagonist to tears with his willingness to kill his True Companions in cold blood, including the eponymous one, who starts bawling like a little kid when he realized that his former best friend-slash-substitute-brother is serious about killing him. A special mention goes to him telling a very useful, deeply loyal teammate (who was also in love with him) who had just been taken hostage not to move - naturally, her expression relaxes into a blissful smile... and then he stabs her along with her captor.
- Sasuke himself has it when he learned that the Hidden Leaf Village is truly responsible for the Uchiha Clan Massacre, giving him a reason of wanting to destroy it.
- Dragon Ball Z: Nappa was willing to fight the much stronger Goku, until, of course, Vegeta betrayed him, and he was unable to do anything to defend himself.
- This happens to Trunks and Goten; they were more than willing to fight Buu alongside Vegeta until he (apparently) offed Trunks (who was briefly shocked by his dad doing this to him), after which Goten entered a very brief Heroic B.S.O.D. after this before Vegeta took him out as well. Obviously, this was due to Vegeta needing to be alone to sacrifice himself against the monster he brought into this world.
- Magical Project S: Sammy the magical girl had no problem beating the monster of the week until she discovered her worst enemy was her best friend Pixy Misa; she couldn't believe it. The same happened to Misao (aka Pixy Misa); she ran away from her home and her school when she believed that she had betrayed her best friend.
- Kaleido Star's Sora puts up with a hell of a lot of grief in the second season — not that the first season was a picnic, but still. At various points in the storyline, she is demoted, fired, paired up with a partner who verges on sociopathic and spends the whole series struggling to earn the title of Kaleido Star — a title which she had won fair and square by the end of the first season, only to be usurped by a newcomer who wields far more power than any newcomer to the troupe has a right to. Through most of it, she remains perky and cheerful, convinced that everything will work out all right in the end... but when Layla, Sora's idol, suddenly turns on her and sides with Sora's rival, the poor girl finally cracks.
- In Pandora Hearts, Jack is forced to kill his best friend Glen at the Tragedy of Sablier because Glen allegedly snapped and ordered the massacre of every man, woman, and child at the Baskervilles' mansion. In the biggest Wham Episode of a series already known for its HSQ, however, it's later revealed that Jack himself was the one who betrayed (Oswald) Glen's trust by opening the doors to the Abyss and attempting to bring the entire world down into it so that he could meet Lacie again. Ironically enough, just the night before Jack's betrayal, Glen asked his servant Gilbert whether or not he trusted Jack, and when the latter replied that he did, Glen decided to do the same.
- Oz is betrayed by Jack when it's revealed that Jack was using him all along and actually considers him to be subhuman. Arthur Barma also applies and is of the friendless variety, as he was betrayed by Jack as well. Jack only befriended him so that he could later force him to write an account of the events of the Tragedy of Sablier that made Glen appear to be the villain and Jack the hero.
- Hot Shot manages to hold off the bulk of Megatron's Decepticons in Transformers Armada (albeit while wielding the Star Saber). However, when Sideways betrays him and defects to the Decepticons, he falls to his knees and passively lets the Decepticons beat him into a metallic pulp.
- In Berserk, Griffith faces all sorts of challenges to his dream without flinching, but when his best friend, the protagonist Guts, leaves him, he throws his dreams away with a stupid mistake. A year later, after being broken in both body and spirit, he clings to his humanity and even his hope... until he finds out that Guts and his other friend, Casca, are in a relationship and are discussing the necessity of him leaving the Hawks again. Then he snaps, resulting in an epic FaceHeel Turn as he makes a Deal with the Devil to become the fifth member of the Godhand and sacrifices the Band of the Hawks, saving Guts and Casca for last.
- Played with in One Piece: Nami steals all the treasure and runs off with crew's ship. In another arc Nico Robin openly denounces her affiliation. Various reactions ensue, reasons get explored, bad guys get beaten and Straw-Hats go on to next adventure together.
- Pet Shop of Horrors demonstrates the second type of Et Tu, Brute?. Leon is convinced that Count D is a serial killer by proxy. Yet the two form a fairly intense friendship regardless, with Leon spending most, if not all, of his spare time with D. Despite the constant banter and Leon's empty threats of arrest, the detective is clearly fond of D, and while he can't disregard the Pet Shop's body count, he doesn't let it disrupt their personal relationship. What does cause the breakdown in their association seems relatively minor by comparison to murder, but the intensely personal nature of the betrayal makes the difference: D sends Leon's little brother Chris, who D and Leon have been looking after for the past year, back to his adoptive parents (actually his aunt and uncle) without telling Leon what's happening. Moreover, Leon is distressed by D's apparent lack of regret or sorrow over losing Chris.
- Arguably, it's D's reaction (or lack thereof), to the above event that constitutes a "betrayal" to Leon: for one, D doesn't send Chris back, Chris decides to go by his own free will, and two, since Chris is talking again, he couldn't stay in the petshop even if he wanted to. This is emphasized in the end of that chapter, and even earlier in the story. What really gets to Leon is D being (acting?) completely indifferent over witnessing Monica's death and distancing himself from Leon, treating him and, as Leon feels, Chris too, coldly and indifferently, as he did when they first met.
- A variation occurs in Code Geass. About 2/3 of the way through the first season, Lelouch learns that his best friend Suzaku is the person who's been constantly wrecking his plans. Rather than feeling betrayed, he simply redoubles his attempts to recruit Suzaku for La Résistance. At almost the exact same point in the second season, after lots of misunderstanding and misdirected rage, the two are close to patching up their friendship...when soldiers rush in and arrest Lelouch for being a terrorist. Lelouch thinks Suzaku betrayed him (he didn't, he was followed), but it pretty well marks the absolute death of their friendship and the moment Lelouch stops showing Suzaku any form of respect or mercy.
- Then after being exposed to Lelouch's Broken Pedestal, Suzaku quickly becomes a Knight of Zero, to be specific, the Knight above Knight of Rounds and The Dragon to the Emperor Lelouch. So...
- And that apparent betrayal is followed by one on part of the Black Knights, who were falsely convinced by Schneizel. Murphy's Law really has it in for Lelouch here.
- Also, Suzaku has it on his side when he found out Lelouch has been opposing him as Zero, effectively ruining his plans to defeat Britannia by working with it so that he can change it from the inside.
- If Kazuki has any plot relevance in a particular arc of Get Backers, this will happen.
- Dio from Last Exile despises and fears his sister, but he can handle facing her as long as he has Luciola on his side. When he believes (possibly correctly) that Luciola has betrayed him to her, he snaps and hits him across the face.
- Yomi from Ga-Rei -Zero-. Short story: she killed a fellow exorcist who is also a fellow clan member, in defense and in a partially-justified rage. She expected her fiancee and her little sister to come to her defense, since she lost her capability of speaking after that battle. However, her fiancee never comes for her due to family honor. The final straw was her coming to a conclusion that even her little sister believes that she's guilty, and she went the Griffith's way.
- It should be noted that said fiancee was working himself ragged(to the exclusion of his other, extremely important work) trying to prove her innocence so she wouldn't be cast out, and making preparations to take care of her in her disabled state, regardless of the outcome of his investigation. So even though she thinks he abandoned her... he's the one who was there for her the most. Which only makes it more tragic.
- Utena is stabbed by Anthy in the second to last episode of Revolutionary Girl Utena.
- The Kira Task Force in Death Note reacted to this when they finally find out Light Yagami is Kira in the end, especially Matsuda.
- Light himself seems to react this way a little bit when Matsuda attacks him at the warehouse. "Matsuda, you idiot! Do you know who you're shooting at?" A unique example since Matsuda is reacting to Light's own betrayal when this happens.
- This could also apply to L. In one episode of the Death Note anime, L tells Light that it'd be unfortunate if Light was Kira because he considers Light to be the only friend he's ever had. Of course, though, L realizes Light betrayed him as Light smiles at his death. Although, some argue that L was simply lying to trip up Light.
- In StrikerS Sound Stage X, Teana is rather badly shaken by the discovery that Runessa Magnus, whom she had come to trust enough to offer her a permanent partnership, is the mastermind behind their current case.
- In Vampire Knight, Zero has this feeling when he found out Yuki is a Pureblood vampire all along.
- Used in episode 15 of Aldnoah.Zero, during the battle between Inaho and Slaine. Saazbaum jumps in, eager to give some payback to Inaho. Despite this, Inaho still manages to exploit his weaknesses, though he ends up getting killed by a trap Slaine had set out earlier in the episode. Though Slaine meant for it to be used on Inaho, he takes this opportunity to stab Saazbaum in the back for shooting Asseylum, then uses Saazbaum's death to further his own goals within the Vers ranks. To his credit, Saazbaum's reaction to all this is a smirking "Not bad at all.".
- Ishida's friends betray him and make him into a scapegoat rather than face punishment for their part in Nishimiya's bullying. Afterward, to add insult to injury, they also start bullying him.
- In Reincarnation No Kaben, Ironically has this trope, group of 'Greats' get betrayed by Ceasar which was a spy for Sinners all along from beginning..
- In Brave10, Isanami doesn't take well to Ana being a False Friend all along, and exiting having dealt serious damage to Rokuro and Sasuke. Neither does Sasuke, for that matter.
- In Origin: Spirits of the Past, Jessica serves as Shunack's right-hand woman in the Ragna Army. At the end of the film, when she realizes that Shunack is going to betray the Ragna Army, she is understandably outraged.
- Happens to Issei Hyoudou in High School DXD when his first girlfriend Yuma Amano turns out to be the Fallen Angel Raynare and he gets Impaled with Extreme Prejudice.
- One purpose of The Last Supper is to depict the Apostles' collective surprise upon learning one of their own has betrayed them. Besides Jesus, none of them knows who the traitor is, but the shadows don't lie, and neither does Judas's expression.
- In the comic series Preacher, Jesse quickly forms a best buddies relationship with Irish vampire Cassidy, travelling across half the world to save him at one point. But it's not long before Cassidy is trying it on with his girlfriend and later, after Jesse's apparent death, Cassidy manages to seduce her, getting her hooked on drugs in the process. When Jesse comes back (after learning of a long line of similar screw ups in Cassidy's past), he's not exactly pleased.
- There's a scene when Jesse comes back, sees his girlfriend kissing Cassidy, and faints.
- In Robin' this is Tim's basic reaction to realizing that the Bad Future (caused by the fall of his hero friends) he'd been obsessively trying to find ways to avoid was Batman's idea of a test.
- Basic premise of Avengers Disassembled. The Avengers were facing many threats, villains, and betrayals. But one of their core members, somebody they deeply trusted, suddenly snapping and trying to kill them, with clarification she's Not Brainwashed, was enough to disband the team.
- In one Batman comic, Two-Face was genuinely reformed and about to leave Arkham. Then the Joker came along and started messing with him that his best friend Bruce Wayne and his girlfriend were together. As a final push, the Joker slipped an already suspicious Two-Face a fake newspaper that Bruce and his girlfriend were marrying. He broke out of Arkham to kill Bruce.
- In PS238, Zodon's 'childhood escapades' took a decisive turn for the worse once he overheard his parents talking of whether it'd be better if he hadn't been a metahuman.
- In Archie Comics' Sonic the Hedgehog, Princess Sally is forced to use Bunnie's old roboticizer in order to combat Mecha Sonic (Sonic put through Unwilling Roboticization) and plans on using it on someone. Rotor brings it out and points out that doing so might put them at Robotnik's level. Sally replies "Et tu, Rotor?", then points out that they've kinda hit the Godzilla Threshold at this point.
- In Lilith, Commodus has a rather peculiar one when the time-traveling title character allows him to catch his would-be assassins Eclectus (his chamberlain), Narcissus (his personal trainer and sparring partner) and Marcia (his Christian concubine) in the act, remarking not on their friendship but on their utter stupidity in betraying the one man who put them in positions of power, keeps them there against the opposition of the Roman Senate, and, especially, adopted policies favorable to the Christians just to favor Marcia (who, after being caught betraying Commodus, became the first victim of a new persecution).
- Ultimate X-Men: Magneto reacted to all the attacks with disdain, until his helmet (that prevents mind attacks on him) was removed by Quicksilver. His son, the one he always treated like dirt.
- Maylu's Revenge has this feeling about Roll after the events of "Evil Empress Roll". Also, Roll has this feeling about Maylu when she learned she defected to World Three to get revenge on her for being brainwashed which resulted in her unable to continue in the N-1 Grand Prix.
- Graduate Meeting Of Mutual Killing: In the Chapter 3 trial, Reiji Ohmoto is accused of the murder. His brother Yukio defended him to the very end, and doesn't take it well when it's confirmed and revealed that Reiji really was the mastermind behind the murder and purposelly used Yukio as a pawn to get himself free.
- The Great Alicorn Hunt: Twilight Sparkle gets a moment of this in chapter 28 when her loyal friend Spike (who has been incinerating much of the admittedly pointless paperwork between her and her captain) asks Twilight to give poor Flash Sentry a break.
- In Ambience: A Fleet Symphony, Suzukaze is shocked when, while defending her ship sister Murasame from an aggressor, Murasame, instead of being grateful, says she is ashamed of Suzukaze's actions. Suzukaze is so distraught that she flees from the fleet.
- Blood and Honor: Despite all evidence to the contrary, Lord Sanguis firmly believes that Darth Baras would never betray her. When he does, it hurts her deeply. Quinn's own, smaller betrayal, as well as his attempt to leave her on Taris, are very unpleasant surprises as well.
- Happens in The Lion King when Scar throws his brother, Mufasa, to his death.
- In Cars 2, Lightning McQueen gets this after his best friend Mater causes him to lose a race in the World Grand Prix.
- A case where the betrayal actually does cause a FaceHeel Turn: Kung Fu Panda, during Tai Lung's Start of Darkness. Master Shifu betrays his prize pupil and adopted son—not by denying him the Dragon Scroll, but by raising him to believe he was destined to one day earn it as a matter of course, filling him with pride and dreams...and then, when Oogway advised otherwise, refusing to defend, stand up for, or even support his son. No wonder the snow leopard went insane and goes on his Rage Against the Mentor.
- The Lorax has an implied example of this. After his HeelFace Turn and Blatant Lies, the Once-Ler offers Pipsqueak a marshmallow, thinking that he had one friend among the animals whose home he ruthlessly destroyed for the approval and love of his family. The little Barbaloot gives him one short look and exits with the rest of the animals.
- In the third movie of the Shrek series, Princess Fiona and the other Princesses' betrayal by Rapunzel, who was in love with Prince Charming.
- Henry J. Waternoose III to James P. Sullivan in Monsters, Inc..
- Happens in Frozen when Anna is taken back to Hans, her fiance, so that they can share true love's kiss to melt her frozen heart. Just as they were about to kiss, Hans reveals his true intentions; he never loved Anna. It was all an act to get closer to the throne of Arendelle.
- In Hercules, Meg is working for Hades, although not evil. When Phil tried to show this to the titular character instead of listening on her conversation with the villain to see if she will go through with his plan or not, Hercules doesn't believe him until Hades ended up revealing it to him, putting him into a Heroic B.S.O.D. from it.
- In Zootopia, Judy at the press conference, repeats the theory from the unnamed doctor at Cliffside Asylum that predators may be "going savage" due to their biology and were "reverting to their primitive state" for some unknown reason. Nick in hearing this from the person he has opened up to about his traumatic childhood experience with racism against predators, feels personally betrayed and is deeply upset, leading to their Plot-Mandated Friendship Failure.
- When the protagonist of Braveheart learns that King Edward's personal bodyguard is none other than Robert the Bruce, he is so devastated that he sinks to his knees and can't move at all - and nearly gets captured because of this.
- In the film of Prince of Persia: The Sands of Time , when the King of Persia was apparently assassinated by his own son Dastan, his last word was "Why?".
- In the film Red Dawn (1984), the Wolverines seem to have no problem performing guerilla warfare against the occupying Soviet forces, gunning down countless Soviet soldiers. However, it's only when one of their members betrays them to the Soviets (he was captured, and they forced him to betray his buddies, otherwise they'd kill his father), and they are forced to kill him, that they realize how deep in the war they are in. After that, things progressively go downhill for the Wolverines.
- TRON: Legacy : Flynn Sr. is pretty much broken already, but then he gets a good, solid look at the distinctive Tron Lines on Rinzler and realizes...
- In Star Wars: Episode III: Revenge of the Sith, the horribly Wrong Genre Savvy Anakin Skywalker assumes this is what's happening to him.
- Anakin Skywalker: (To Padmé Amidala, his wife) The Jedi turned against me, don't you turn against me!
- To say nothing about how poor Obi-Wan Kenobi must have felt when he discovered that Anakin had turned to The Dark Side and led the massacre of the Jedi Temple, not even sparing the children.
Obi-Wan Kenobi: (watching Anakin kneel before Darth Sidious on hologram) It can't be...it can't be...
- The Force Awakens has a villainous example: a stormtrooper known as "Nines" is very angry when he learns that his old squadmate Finn defected to the Resistance.
- The Live-Action Adaptation of MW has Father Garai attempting to betray Michio Yuki over to the police, something he wouldn't do in the manga.
- Fredo Corleone betrays his brother Michael in The Godfather Part II.
Michael Corleone: I know it was you Fredo. You broke my heart. You broke my heart.
- In John Woo's The Killer, the protagonist Ah Jong gets this after learning from Fung Sei that Wong Hoi betrayed him and sent his hitmen after him.
- James Bond:
- A relatively mild case where the betrayal actually does leads to the Fallen Hero's FaceHeel Turn in Skyfall. During the beginning of the film, M asks for James Bond to leave Tiago Rodriguez/Raoul Silva where he was, not only because he had been engaging in unauthorized hacking against the Chinese, but to hand him over to them in exchange for the prisoners held by the Chinese government. No wonder the guy becomes a cyber-terrorist bent on revenge against M.
- When the Big Bad of GoldenEye turned out to be Alec Trevelyan/006, who faked his death in the Arkhangelsk facility, Bond's reaction to this was one of pure shock and anger.
- In Transformers: Dark of the Moon, the Autobots' betrayal by Sentinel Prime, who kills Ironhide.
- In Trading Places, Louis Winthorpe is shocked when he's informed his former employers, the Duke Brothers, were responsible for his downfall because of a bet.
Louis Winthorpe: The Dukes ruined my life over a bet? For how much?
Billy Ray Valentine: A dollar.
Winthorpe: One dollar? All right... That's the way they want it? No problem.
(cut to Winthorpe loading several rifles)
- In A Face in the Crowd, Marcia is the only person Lonesome Rhodes really trusts, so she's the last one he would suspect of being responsible for his Engineered Public Confession. At Mel's urging, Marcia goes up to Lonesome and confesses that she was the engineer who betrayed him so that she'll never have to deal with him ever again.
- In Ex Machina, Caleb finds himself betrayed by Ava, who leaves him locked in a room where he will die of starvation if not rescued.
- In Dawn of the Planet of the Apes, Caesar has this reaction when he is betrayed and shot by Koba. Even better when you consider this was done to a protagonist whose name is Caesar.
- The Hitman: Early on, Chuck Norris' cop character is suddenly betrayed by his old partner when they're raiding a warehouse where illegal goods are being shipped. Turns out his partner was actually supervising the shipment until he arrived. It's so out of left field that initially, Norris just looks a bit stunned at the bullet hole in his chest.
- In Full Metal Jacket, when Sgt. Gunnery Heartman decides that Pvt. "Gomer Pyle" needs extra help to become a proper Marine, he assigns Pvt. "Joker" to help him. Pyle appreciates Joker's help, and though he never says it, he considers Joker a friend. When Heartman decides that whenever Pyle screws up, the rest of the platoon will suffer the consequences, the other privates get fed up with his failure and hold a "blanket party." After the other privates beat him with soap bars wrapped in washcloths, Cowboy pressures Joker to hit Pyle, and what hurts Pyle the most is that only friendly person there joined in the beating.
- In the Gone series, Sam and Quinn in the first book.
- In The Bible, Judas betrays Jesus. The Jews that once supported Jesus now fervently denounce and mock him, calling for his crucifixion. It's subverted in that Jesus knew about Judas's betrayal ahead of time and, according to the Gospel of Judas, may have even asked Judas to betray him.
- In Jim Butcher's The Dresden Files novel Turn Coat, Morgan survives just fine being on the run for his life after being framed for murder. But let him learn the one person he cares for most thought the worst of him...
"Ana," he said, almost choking on the words. "You. . . you think that I. . . How could you think that I would. . . .?"
He turned his face away. It couldn't have been a tear. Not from Morgan. He wouldn't shed tears if he had to execute his own mother.
But for a fraction of a second, something shone on one of his cheeks.
- Though the person he perceives to have betrayed him gently points out Brainwashed and Crazy is a very real danger in this universe and so the mistrust is not entirely unwarranted.
- This is one of the worst ways you can hurt Harry. It's happened to him twice in his life, with Justin and Elaine before the series starts and Ebenezar in Blood Rites. Possibly the only way to hurt him more is to manipulate him into doing this to his friends.
- This was the tragedy of the Marauders in Harry Potter, as explained in Prisoner of Azkaban. Peter Pettigrew, one of the four iconic best friends (who formed the Marauders, consisting of James Potter, Sirius Black, Remus Lupin and Peter Pettigrow), betrays James Potter to Voldemort. James' best friend Sirius entrusted Peter with the secret of the Potters' hiding place and Peter sells out the Potters to Voldemort by revealing their hiding place to him, sending James and his family to their deaths (save for the Potters' infant son, Harry, who famously survives Voldemort's attack). Sirius went to pieces upon discovering Peter's betrayal. Rather than owning up to his betrayal when Sirius chases him down in a grief-stricken fury, Peter frames Sirius for the Potters' murder and his own killing spree. Sirius was so heartbroken that he broke down into hysterical laughter and was dragged off to Azkaban without struggling.
- In Harry Potter and the Order of the Phoenix Harry calls out Cho for averting this when her best friend Marietta sells out the DA to Umbridge after attending lessons for six months. As Harry rightly pointed out, Marietta was willing to let everyone involved, including Cho, get expelled.
- This trope is also heavily toyed with in Half-Blood Prince when Severus Snape kills Albus Dumbledore; Deathly Hallows subsequently reveals that Dumbledore asked Snape to kill him both so Draco Malfoy wouldn't have to and because Dumbledore was dying from a Horcrux-inflicted curse already.
- Animorphs got into this when Cassie let Tom get away with the morphing cube.
- Bertie Wooster's reaction whenever he feels he's been betrayed or let down by Jeeves. It even merits a Julius Caesar Shout-Out in "Jeeves and the Old-School Chum". (For the record, Jeeves had taken their lunch out of the car before they went golfing.)
I quivered like an aspen. I stared at the man. Aghast. Shocked to the core."You, Jeeves?" I said, and I should rather think Caesar spoke in the same sort of voice on finding Brutus puncturing him with the sharp instrument.
- In the Hurog duology, Ward is heartbroken whenever someone close to him reveal that they believe him capable of using Klingon Promotion. At one point, his own brother tells him to please get it over with quick, and Ward doesn't even understand what he means, as the concept of killing his family to get a title is so alien to him. When he does understand it, he's utterly horrified by the implication.
- In The Oaken Throne, the Starwife is betrayed and murdered by her trusted handmaiden, Morwenna.
- Song at Dawn Al-Hisba betrays Dragonetz by burning down the paper mill they created together. However, he only did it because the Archbishop twisted his arm and had attempted Dragonetz's murder three times thus far.
- A Song of Ice and Fire: The Night Watchs Lord Commander Jon Snow gets knifed in a mutiny by several of his fellow Black Brothers, who believe that many of the changes he is making will doom the Watch.
- The Infernal Devices:
- Nate. What's with the constant brother/sister betrayals in Cassandra Clare books?
- And later, Jessamine Lovelace betrays the Institute for Nate.
- In the Left Behind book Assassins, Enigma Babylon leader Peter Mathews was killed in this manner by the ten subpotentates when he was invited to attend a Nasty Party where he was killed with Feather Flechettes from an ice sculpture made in his image. As it turns out, Peter's death was foretold by Scripture in the Book of Revelation, speaking of the "ten horns of the beast" that would hate the whore, that would "eat her flesh and burn her with fire", as Peter's body was then cremated under the cover story that he contracted a contagious disease.
- The Silerian Trilogy: Josarian is completely devastated when he finds out that he was sold out by his cousin, whom he was close as a brother to.
- Game of Thrones: The show is very fond of this kind of classical, Shakespearean flavoured betrayal:
- Jon Snow struggles against the mutineers at Castle Black quite a bit, until a boy he had taken on as his steward and personally mentored steps up, and all he can do is say "Olly?" When he's later brought Back from the Dead, he seems more traumatized by Olly's part in his assassination than the assassination itself.
- Robb Stark is betrayed by Theon Greyjoy in Season 2 when Theon seized Winterfell and this is reaction upon learning this. He is also betrayed by Rickard Karstark and later to his death by his bannerman Roose Bolton and Walder Frey in the Season 3 episode "The Rains of Castamere", although he's too numb to register it. Furthermore, he feels deeply betrayed by his mother Catelyn when she releases the Kingslayer (Jaime Lannister) behind his back.
- Shae is this to Tyrion in Season 4, which is implied to be revenge for sending her away. She returns as Cersei's star witness at Tyrion's trial and is notably the only person at his trial who tells an outright lie against him as well as twisting the knife further and citing their most heartwarming moments together and twisting them to humiliate Tyrion in the most gutwrenching possible way. This is the testimony which utterly breaks Tyrion and launches him far past the Despair Event Horizon, causing the poor man to just fucking lose it and explode with several decades worth of bitterness and rage at his ungrateful family and the ungrateful nobles of King's Landing.
- Missing the bigger picture, Tywin can hardly fathom that his children would be capable of rebelling against him. His miffed line, "You shot me," ("why, this is violence") carries far more indignation and disbelief than it does fear or pain, like that of which Julius Caesar expressed during his own assassination.
- Alton Lannister is killed by Jaime, his own older cousin, after telling him that he's his number one fan and that he would do anything to help him.
- In Season 3, Gendry enthusiastically joins the Brotherhood without Banners, claiming that they'll be the closest thing to a family he'll ever have... only to be sold by them to Melisandre the next episode.
- The new Battlestar Galactica has some examples. These include: Starbuck's infidelity between Lee and Samuel Anders(Lee also does the same to his wife during this), Gaeta's Start of Darkness and participation in a coup, Ellen Tigh's infidelity, Saul Tigh's murder of his wife, Baltar's desertion of his cult, and Cavil's actions towards anyone who disagrees with him.
- One Star Trek: The Next Generation had an abandoned Romulan prison camp full of Klingons, in which the two cultures merged and interbred. When Worf arrives and tries to teach the half-breed children about Klingon honor, the former Romulan prison commander sets up to execute him, and is standing there with his disruptor trained on Worf and all of the children go over and interpose themselves. He looks like he is about to pull the trigger anyway, but then his half-Klingon daughter (who has a crush on Worf) walks over to join them and utterly crushes his resolve.
- A better Star Trek example comes from Deep Space Nine when a recurring character reveals himself to have been a mole for the terrorist/freedom-fighters the Maquis. Although the Maquis in general are depicted as a moral grey zone for the show (their cause is sympathetic but their methods illegal), Cpt. Sisko takes it VERY personally, to the point of destroying a planet's biosphere to keep the Maquis from using it. The former Mole even lampshades this trope in a later episode after the Maquis have been all but eliminated, pointing out to Sisko that it wasn't their agenda or even their methods that pissed off Sisko so much, it was the BETRAYAL by those Masquis who had once been Star Fleet officers, turning their backs on the Federation.
Odo: Sir, have you ever reminded Starfleet Command that they stationed Eddington here because they didn't trust me?Sisko: No.Odo: Please do.
- Ironically, that same mole had previously betrayed Sisko by sabotaging the Defiant to stop Sisko from pursuing a ship...on orders from Starfleet.
- There's an even clearer example earlier on, where Sisko discovers an old friend and colleague to have switched sides. He's known the man for decades, and has always seen him as someone who shares his values. The only difference between the two is that his colleague has experienced the problems that led to the foundation of the Maquis first hand.
- In the episode "Inquisition," Dr. Bashir is hurt when even Sisko suspects him of suppressing memories of betraying the Federation. It is later revealed that everything that happened after a certain point in that episode was fake, including Sisko's reaction.
- Comedically referenced in the Mystery Science Theater 3000 episode Riding With Death, when a rift occurs between the protagonist and his obnoxious redneck buddy. Crow mournfully supplies: "Et tu, Billy Bob?"
- In Buffy the Vampire Slayer: Amy, Angel(us), Spike (occasionally), Faith, Billy Fordham, Willow, Gwendolyn Post and the list goes on. Even Xander may belong here, depending on how you interpret Xander's Lie.
- In "Helpless", Giles has Buffy Brought Down to Normal on the orders of the Watcher's Council. Buffy acts like this is a Parental Betrayal and swears to kill him if he ever lays hands on her again. They reconcile only because the Council fires Giles at the end of the Test after he tries to atone by helping Buffy. However in Season 7, Giles tries to arrange Spike's death, causing another breach between them that carries over into the comic series.
- Wesley, on the Angel side, betraying Angel and taking Connor.
- After the Fall has Gwen betray the team because Gunn (who's a vampire) and the Big Bad, says that he can help her. Her boyfriend, Connor, is especially hurt by this.
- In Merlin, Morgana leads Uther on to believe she's close to him, although they argue at times, and then she betrays him and seizes the throne. Ditto could be said for her and Arthur.
- Morgana herself reacts like this when Merlin poisons her to save Camelot. To be fair, at the time he didn't have any other choice and he knew she had already betrayed them.
- Firefly: The episode "Ariel" has Mal angry at Jayne because he feels personally betrayed by Jayne who called the Feds on Simon and River while they were doing a job. This shouldn't come as much of a surprise to viewers, who have seen Jayne betray/defect in the past. Especially in light of the pilot episode, where Jayne says it'll "be an interesting day" when the money is good enough for him to sell Mal out.
Mal: Next time you stab me in the back, have the guts to do it to my face.
- In the White Collar episode 'The Dentist of Detroit' Mozzie is in danger from the Detroit Mob, and when Peter and Neal try to help him, Neal is forced to 'betray' him by giving him up to Peter as the Dentist of Detroit, to which Mozzie responds 'Et tu, Neal?' in a facsimile of this trope.
- Brutus' betrayal and assassination of Caesar is recreated in Rome without the actual sentence being pronounced. Ciaran Hinds' facial expression, especially his eyes, carries the question "Et tu, Brute?" silently. Very effective.
- In the Ashes to Ashes episode "Traitor", it is discovered that DC Chris Skelton has been feeding information to corrupt cops for the majority of season 2. This is the only time Gene Hunt ever becomes teary eyed and he is sent into a BSOD.
- This is especially heartbreaking given that the traitor is one of the most timid and innocent cops in the station and has previously turned down any and all temptations of police corruption.
- When the traitor is Interrogated, Gene (who usually beats the crap out of suspects to get information) remains in a BSOD and barely talks at all while his DI Alex conducts the interrogation. When the Interrogation is over he gives a look of pure disgust and leaves the room, slamming the door behind him.
- Inverted on Xena: Warrior Princess with Caesar's assassination. In Shakespeare's Julius Caesar, Caesar wilts upon seeing his close friend Brutus among his killers. But in Xena, Caesar had been cast as a much younger man(instead of middle-aged like the real Caesar was), and his response to realizing what was about to happen was an angry "And you, Brutus!"
- Babylon 5: Michael Garibaldi winds up on both ends of this before it's all over.
- At the end of the first season, Garibaldi gets wind of a conspiracy to kill Earth Alliance president, but before he can do anything he's shot In the Back by his own second, Jack. After he recovers and it's revealed what happened, he goes to Jack's cell, demanding to know why, then promising to be the one to push the button at his sentencing.
- In season four, Garibaldi is under More Than Mind Control which eventually leads to him turning Sheridan over to the corrupt Earth Force. After this, Bester comes and releases the mental programming, leaving Garibaldi in his right mind again, and fully aware of what he's done. He first tries to get in contact with his former allies, but they're not exactly sympathetic, and he has to beg Lyta to scan his memories to prove his story.
- Lifetime has an entire series entitled "I Killed My BFF."
- Scorpion season finale Swiss Family Scorpion has "et tu, Happy?"
- Legends of Tomorrow in Aruba-Con "Et tu, Sara?" is directed at White Canary by Citizen Steel when she agrees they should return the ship to Rip
- The protagonist of DJ Play My Song (NO, LEAVE ME ALONE) says "Et Tu, Brute" after guest singer DeStorm starts singing along with the woman who's ruining his life.
- Bob Backlund had this feeling after his manager, Arnold Skaaland, caused him to lose the WWF championship to The Iron Sheik by throwing in the towel.
- The Undertaker had this reaction when Paul Bearer turned on him for Mankind in a boiler room brawl.
- Raven was really hurt when Perry Saturn left his Flock in WCW. More, Raven did not even know he could be hurt in that way anymore until it happened.
- CM Punk felt this way when Paul Heyman cost him a Money In The Bank Ladder match.
- Astro Rey Jr after his La Ola Blanca partners Hijo del Dr. Wagner and Médico Asesino Jr. attacked him and left Astro Rey for the Clown Corp during the World Wrestling League's 2014 Dream Matches Tour.
- Played with in The Four Gospels regarding Judas betrayal of Jesus and Peters denial of Jesus. Both acts are treated as shocking, but Jesus foretells both occurrences. Jesus later forgives Peter after His resurrection, and Peter once again becomes the lead disciple. Judas however never lives it down.
- Psalms 41 and especially 55 both describe this type of betrayal. The Gospel writers point to these psalms as prophesying Judas betrayal.
My companion stretched out his hand against his friendsHe violated his covenantHis speech was smooth as butterYet war was in heartHis words were softer than oilYet they were drawn swords— Psalm 55:20-21
- Dungeons & Dragons 4th edition mentions in the Codex Of Betrayal articles, which chronicle the origin of devils and their war against the god known only as He Who Was. It's said that when Asmodeus, leader of the rebellion, convinced Greyon, HWW's favorite angel, to side against him, the god cried such tears as to drown mountains, and after such a betrayal, his heart was no longer in the war.
- Older Than Steam: The trope name comes from William Shakespeare's Julius Caesar. As the assassins attack, Caesar defends himself... but when he sees Brutus, his best friend, among the assassins, he gives up and lets himself be murdered - he didn't care about a bunch of strangers armed with pointy things, but having his buddy stab him is another story entirely. The full quote is: "Et tu, Brute? note Then fall, Caesar." Marc Antony during Caesar's funeral would say of Brutus's betrayal that his was "the most unkindest cut of all."
- One alternate interpretation of the line is less of a question and more of a statement, as in "You're next." In real life Brutus only lived another two years after the death of Caesar.
- Max Bialystok calls Leo this in The Producers when he receives a postcard from Brazil and learns what happened to Ula and Leo along with other infamous traitors in history. Both come back and Max reconciles with Leo.
- The titular character of Donizetti's opera Anna Bolena (Anne Boleyn) has one of these moments upon discovering that her best friend and handmaid, Giovanna/Jane Seymour is the woman driving Enrico/Henry VIII's plan to get her executed. But Anna forgives Giovanna upon finding out that she is sorry and is as trapped by the situation as she herself is.
- Fallout: New Vegas: Mr. House essentially invokes this if you kill him. Caesar as well if you had sided with him and then kill him in the aptly-named quest "Et Tumor, Brute?"
- Dr. Klein says this to Dr. 8 in Old World Blues if you get him to side with you in the final battle.
- Final Fantasy XIII Sazh had no problem fighting with Vanille against PSICOM until he realized that Vanille was the reason his son became a l'Cie he was about to kill her and commit suicide. He fortunately came back to his senses.
- Halo: The Arbiter fought for the Covenant against humanity with no problem at all, but when the Prophets (who had given him a second chance by making him the Arbiter to begin) betray him and the entire rest of his species (with the Arbiter himself betrayed by the Prophets' main enforcer Tartarus), the Arbiter is forced to ally with humanity and lead a rebellion against the Covenant.
- Video game example: The Suikoden series. A running theme through the games is the main hero having to deal with the betrayal of a close friend or ally — which he usually has the option of forgiving. (Doing so helps determine what ending the game gets.)
- The first major blow in the Break the Haughty act played on Luke in Tales of the Abyss is his mentor Van betraying him and leaving him for dead.
- Tales of Destiny: Stahn gets pretty upset when Leon betrays the party. So do the others, to lesser extents. But Philia took it worst of all, as shown the the sequel when she talks about him.
- Later, Ilene sides with Hugo rather than Stahn and commits suicide. Stahn goes into a full out Heroic B.S.O.D..
- Neverwinter Nights: Everyone's reaction (possibly including the player) to Aribeth's FaceHeel Turn.
- The Mass Effect series has plenty of examples, beginning with the second death in the series: Sacrificial Lion Nihlus is shot in the back of the head by his old colleague Saren.
- Garrus's whole loyalty mission is entirely focused on him finding and dealing with someone who did this to him. After Shepard recruits him, he tells him about a traitor named Sidonis who sold out his squad to the various merc groups on Omega and told them where the squad were hiding, causing the mercs to track them down and kill everyone but Garrus. You find out later that this wasn't quite the case, as the mercs actually threatened him at gunpoint for the location of the base, and he feels very guilty for actually giving in to their demands. While Garrus at first still wants to execute him for being a coward, you can convince him to back down.
- This also happened to Zaeed Massani, courtesy of Vido Santiago. He and Vido founded the Blue Suns mercenary group as a business venture over twenty years ago. While mercenary groups aren't exactly known for being morally scrupulous, Zaeed tried to keep the Blue Suns fairly clean. Vido, objecting to this because it cut profits, turned Zaeed's men against him. He paid a group of them to hold him down while he shot Zaeed in the head (Zaeed survived).
- Shepard has a Heroic B.S.O.D. when the Council pulls him/her off the hunt for Saren. For a Paragon Shepard, this comes as a real blow.
- Shepard him/herself can do this in Mass Effect 3 for various reasons. A particularly bloodthirsty player can personally kill four close friends - Mordin, Wrex, Legion and the Virmire Survivor - in a single playthrough.
- Fenris of Dragon Age II is a former Tevinter slave on the run from his master, Denarius, who is... not a nice man. He catches up to Fenris in the last third of the game, while Fenris is in Hawke's company, and Hawke has the option of fighting him off—or giving Fenris back to him. Fenris hits this reaction hard, especially if he and Hawke are friends, and especially if he's in a romance.
- In Starcraft, there tend to be a lot of instances of people betraying others. In SCII, Tychus reveals that he was given an order to kill the newly de-infected Kerrigan, regardless of the fact that she's no longer zerg, and as a result Raynor has to kill him.
- In Mega Man X 7's prologue, when Axl and Red Alert were infiltrating the base of a maverick. His second in command seemingly finds him, and then while leading him away, he shot the guy in the back. However, in this case, it was a subversion, as the actual second in command had actually been killed earlier by Axl, and the "second in command" who shot his boss was actually Axl.
- Cole Phelps in L.A. Noire has no problem working with Roy Earle, despite the fact they don't like each other until he discovers he's the one who reported his affair with Elsa Lichtmann to the corrupt officials.
- Dante in Devil May Cry is hired by Trish to look for Mundus in an island. This is because she's working for him. When Dante found that out, he is not happy about this. He and Trish finally make up in the end, anyway.
- In Dm C Devil May Cry, Dante has been working closely with Kat and Vergil to aid "The Order" to overthrow the hold the demons have on the world at Mundus's control. Then after Mundus falls, Vergil reveals that his efforts were working to remove Mundus from power and seat himself and Dante as rulers of humanity going forward. Dante is shocked by this and refuses to accept Vergil's outcome, which eventually draws the brothers into battle.
- In inFAMOUS, Cole is incredulous when Zeke attempts to activate the Ray Sphere a second time, which would further devastate Empire City because Zeke really wanted superpowers. Even after the "asshole makes the choice to kill thousands," in Cole's words, it doesn't do anything because Zeke's not a Conduit. Even so, Cole is so stunned by Zeke's betrayal that he hardly notices when a tower collapses right on top of him.
- While we never see Cipher's reaction to his trusted wingman Pixy's betrayal in Ace Combat Zero: The Belkan War, many players were emotionally shaken by it.
- A double-wammy in Arc the Lad: Twilight of the Spirits, Darc forms an alliance with Delma and her power-hungry brother Densimo. When his father's killers arrive, they give Densimo a furble, which he can eat to expand his power. Densimo takes the offering without hesitation. Darc is also betrayed by his master Geedo, who treated him like crap but he still loved her for caring for him. When he realized how little he meant to both, he went off the deep end and killed both of them as well as the murderers, and vowed to become king of the Deimos.
- Jerry Ying to Tequila Yuen in Stranglehold.
- Connor from Assassin's Creed III is none too pleased when he found out George Washington is the culprit in the burning of his village, and also the fact that his father, Haytham, has been hiding this information from him that he cuts his ties with them both.
- At the midpoint of Assassin's Creed Origins, this hits Bayek and Aya as Cleopatra, who they just helped take the crown from her brother Ptolemy, has betrayed them by allowing Lucius Septimus, one of the Order of the Ancients to remain at her side, ousting Bayek and Aya from her court. The trope namer is played straight at the end of the game with the Ides of March, starting with Aya getting the first stab into Caesar.
- Two noteworthy examples from Xenoblade. Dunban is utterly appalled with his old war buddy Mumkhar betraying his entire species. Though in this case Mumkhar never really liked Dunban while Dunban always considered him a friend and didn't notice the jealously Mumkhar harbored for him. The second example would be Dunban and the whole gang being horrified to learn that Dickson, Dunban's second old war buddy and a father figure to Shulk was deceiving them the whole time and plans to kill them all.
- The third example is Egil's belief that Mayneth has betrayed him. Egil is disappointed the remaining members of his species are against his genocidal plans but when the god he knows personally tries to stop them he downright almost cries. His behavior clearly brings great pain to Mayneth too. Terrific voice acting really hammers home how personal the betrayal feels. Also a bit of an odd case since the hero character is the one being accused of betrayal.
- In Assassin's Creed: Revelations, Altair's younger son Sef was killed in the coup that occurred while Altair was away. The assassin who stabbed Sef to death twisted the (figurative) knife by claiming that he was being killed on Altair's orders.
- Celestian Tales: Old North: After Alain reveals that the new Levant heir is Sophia's unborn child, Severin angrily attacks him, stating that because Alain is infertile, not Sophia as widely believed, he couldn't possibly be the child's father, and therefore the child is not a legitimate heir.
- In Fire Emblem Fates, the unfortunate protagonist will be getting this from someone since they have to decide between siding with their birth family or their adoptive family in a war. Taking A Third Option means getting this from nearly everyone, though they do eventually get their siblings on both sides to join them.
- Depending on the path you choose throughout the game, this is the usual response from the heroes whenever you take the villainous path in Shadow the Hedgehog.
- In Mirrors Edge, Faith briefly has this reaction when she finds out that Celeste has joined the other side.
- The Ebony Blade in The Elder Scrolls V: Skyrim is a unique two-handed katana with a Life Drain enchantment that increases in power when you use it to kill characters who consider you a trusted friend, reaching its full power after 10 kills.
- Tohsaka to Archer in Fate/stay night's Unlimited Blade Works route. After keeping calm throughout the story, she's devastated and doesn't hide it terribly well when he betrays her twice. On the plus side, the event is a catalyst for her Relationship Upgrade with Shirou. It's also a real bonding experience for her with Lancer.
- Hell, this trope is the only reason Saber exists. Although she fought virtually the entire world as King of England, and never lost a single battle for 12 years, she died at the hands of her own trusted men. As well as Archer, Who ended up getting betrayed and killed by the very people he dedicated his life to protect.
- In the science fiction visual novel Bionic Heart, the protagonist ends up hiding a fugitive android in his apartment because she needs his help in her ontological quest. If the main character chooses to confide in his best friend and coworker Tom, Tom ends up giving up both the protagonist and the android to the police, which leaves them in the hands of the corrupt corporate executives that were pursuing the android in the first place.
- Shizune's bad ending in Katawa Shoujo. Her boyfriend cheats on her with her best friend. The resulting guilt causes their relationship to spiral out of control until she breaks it up- and she blames herself.
- On a less serious note, when Hisao is forcefully woken up by Shizune and Misha, this trope is invoked.
- In the webcomic MegaTokyo, Largo himself points out, in an unusually serious tone, how painful a betrayal can be. In fact much of his dislike for Miho, previously played for laughs, stems from her once being their friend online in an MMORPG gameverse (and seducing Piro's character) before viciously betraying them. This is hinted as part of the reason he is so mistrustful of relationships, something Erika brands as fairly laughable at first before realising how seriously he took it.
- In this Looking for Group strip.
- It's interesting to note that it seems to have been played for laughs as well as (some) drama, instead of one or the other, but that's to be expected of LFG in general and Richard in particular.
- The real Et Tu, Brute? moment is when Cale learns that Pella killed their own soldiers to force Cale to retreat and therefore survive. He knows that his allies aren't the most moral of people, but he thought that she was more idealistic like him.
- Tower of God - Rachel's betrayal of The Hero Baam is the pinnacle of season one. Her betrayal completely breaks him and she gets a free ride from his companions who think they are doing a favor in his legacy. This is also a reason why Rachel is a Walking Spoiler, since much about her is kept secret until that point.
- In the backstory of Girl Genius, Gil and Tarvek were best friends as children on Castle Wulfenbach - Tarvek was the son of a prince, and Gil was an orphan who didn't know his family in a school where everyone was related to royalty. Gil helps Tarvek sneak around the Castle to spy on behalf of his father, and in return Tarvek breaks into a top-security vault to try and find out who Gil's family are. After Gil is found and taken to the Baron, he is told that he's actually the Baron's son, and that he's been manipulated by the son of an enemy into spying on his only family, although Word of God says that he's also Zeetha's twin. To him, telling the Baron where Tarvek hides his encrypted notes is an act of loyalty. To Tarvek, he's just been stabbed in the back after trying to help his friend, and ends up getting sent back to his Big, Screwed-Up Family who all want to kill each other. More than a decade later, and they still resent each other.
- In A Tale of Two Rulers, Ghirahim's betrayal of Ganondorf's trust is clearly seen as this.
- In The Gamer's Alliance, Belial ends up betrayed by his niece Desdemona who turns out to be working for his enemies.
- The Nostalgia Critic has done this in both That Guy with the Glasses anniversary specials: in the brawl to 2D Lee because he sided with the gamers over the critics, and in Kickassia to Film Brain when he turned against Critic because he accidentally killed Santa Christ.
- Chakona Space: In chapter 7 of Tales of the Folly, Neal has been injured in some spaceport drama. Not only are his mates, companions and children trying to tie him down in a sickbay bed, so is his ship. He then proceeds to quote Julius Caesar.
- In Worm, Rachel Lindt, a supervillain, takes it badly when it's revealed that Taylor, quite possibly the only friend that she's ever had, is an aspiring superhero who joined Rachel's gang with the intent to betray them to the authorities. Their friendship afterwards is strained to the point of breaking.
- Marceline from Adventure Time had this several times. Which led her to driving others away so this wont happen again
- As Told by Ginger: When Ginger Foutley finds out from Courtney Gripling that Dodie Bishop and Macie Lightfoot teamed up with Miranda Killgallenin an attempt to break up her and Darren Patterson up.
- Lampshaded when Ginger sees her friends defecting to the other side in "Battle Of The Bands".
"Et tu Dodie?"
- Lampshaded when Ginger sees her friends defecting to the other side in "Battle Of The Bands".
- Villainous example in Avatar: The Last Airbender: In "The Boiling Rock", Azula's spiral down into complete insanity starts when Mai and Ty Lee betray her.
- In the episode, "The Avatar and the Fire Lord", though the relationship between Avatar Roku and Fire Lord Sozin became deeply strained when Roku made it clear that he would kill Sozin if he launched his planned war, they were still friends, as shown when Sozin showed up to aid Roku when his island suffered a massive volcanic eruption. The two men stood their ground and controlled the volcanoes until the villagers had escaped, at which point Sozin realized Roku was vulnerable and betrayed him, leaving him to die on the island so he could fulfill his ambitions of world conquest.
- In the episode "The Crossroads Of Destiny", Uncle Iroh's betrayal by Zuko, his nephew who sold him out to the Dai Li.
- A rather depressing example comes from Batman: The Animated Series. In the episode "Birds of a Feather", the Penguin is released from prison and declares that he's reformed and will become a model member of high society. A group of snobbish aristocrats decide to bring him into their social circle so that they can laugh at his social ineptitude and appearance. He generally doesn't care how life had gotten him down through the rest of the episode, but when he overhears the woman whom he had fallen in love with talking about this plot, he loses it. The real slap in the face is that he had genuinely reformed until this happened.
- The Beetlejuice cartoon has an instance. In the episode, "Mr. Beetlejuice Goes to Town", after Beetlejuice gets elected Mayor of the Neitherworld, he lets the success go to him. Lydia goes incognito as a special interest rep and bribes Beetlejuice into some questionable legislation that gets exposed. After being impeached, B.J. has an Et Tu when he learns that Lydia was behind his impeachment.
- In the backstory of Bojack Horseman, Bojack stabbed his best friend and mentor Herb in the back. When Herb was outed as being gay and caught in a sex scandal, Bojack was persuaded by an executive not to protest Herb getting unceremoniously fired from their show. (A show that Herb wrote and created for Bojack to star in, when Bojack was still a nobody and they were just two friends trying to hit it big.) When Bojack finally tries to make amends 20 years later as Herb is dying of cancer, Herb makes sure to tell Bojack about how deeply it cut to be betrayed and abandoned like that, and how he will never forgive Bojack as a result.
Bojack: You have to believe me, I did everything I could.
Herb: Yeah? Then why didn't you call me? 20 years, you didn't call me. You know what it was like for me? I had nobody! Everyone left! And I knew all those showbiz phonies would turn on me, sure. But you?
Bojack: It's not my fault you got fired.
Herb: I don't care about the job! I did fine, I had a good life. But what I needed then was a friend, and you abandoned me. And I will never forgive you for that.
- Demona's Start of Darkness in Gargoyles, resulting in the destruction of most of the Wyvern Clan.
- Justice League:
- Wonder Woman has no problem working together with Hawkgirl. That is, until the episode, "Starcrossed", when she finds out the latter had been spying on Earth for the Thanagarians. Later on in the series, when Hawkgirl is back in the titular team, Wonder Woman is still raw about the betrayal and has issues trusting her. Luckily, in "The Balance", they're able to work together and make up in the end.
- In the episode, "Injustice For All", Lex Luthor was hit in his armor by Humanite with a "killswitch" device when the latter sneaks up behind him. His last words before blacking out were "Et tu, Humanite?"
- My Little Pony: Friendship Is Magic
- A comedic example happens in the episode, "Party Of One". Pinkie Pie assumes that her friends are turning their backs on her after forcing Spike to admit that they don't like her parties anymore. As it turns out, her friends are setting up a birthday party for her without telling her about it.
- A brainwashed example occurs in the two-parter episode, "The Return Of Harmony". In that episode, Discord, knowing about The Power of Friendship, brainwashes the True Companions into turning against each other. After a Circle of Shame by the Discord's balloons, which tells her that her friends are laughing about her behind her back, corrupted Pinkie Pie's reply to Twilight Sparkle is to be expected when she and the corrupted Applejack found her:
Twilight Sparkle: Pinkie Pie! Are we glad to see you!
Pinkie Pie: Oh you are, huh? Why? Need a good laugh?
Applejack: (watching as Rainbow Dash went flying out of the maze) Well, looky there. Rainbow Dash is flying away. She's abandonin' us.
- To say nothing about how poor Twilight felt when one by one, her friends are acting different from themselves, and when Rainbow Dash went flying out of the maze after what Applejack told her.
Twilight Sparkle: Now I know that's a lie. How can it be?
- A relatively mild example occurs in the episode "Ponyville Confidential". When the Gabby Gums column begins to print false-but-still-damaging stories of the mane six, it's initially suggested to Rarity that since Sweetie Belle works for the school paper, she might know who GG is. Rarity is immediately offended by the implication that her sister would associate with a pony with such blatant disregard for everyponys feelings. Her tune changes immediately once she discovers Sweetie Belle stole Rarity's diary and published it. To drive this home, Rarity confronts Sweetie with "Et tu, Gabby Gums?"
- In Twilight's Kingdom Part 2, Fluttershy is the only of the Mane Six who seems wholly shocked by Discord's betrayal.
- Before her, Shining Armor is likewise stunned that Discord would turn his back on them.
- Discord gets hit with this moments later by Tirek, who he seemed to have thought was actually his friend. It causes Discord to, for the first time in the series, be broken.
- The New Adventures of Winnie the Pooh: In "Rabbit Marks The Spot", when Rabbit tries to teach the others a lesson in digging in his garden for treasure by filling up a chest with rocks, he has a nightmare in which his friends, as stone statues, call him out for pulling such a stunt on them. Upon awaking from his nightmare, he fears that he will be hated forever if they found out what's in the chest. Of course, this is long before it's revealed they actually appreciate what kind of worth the "treasure" has to offer.
- Scooby-Doo! Mystery Incorporated: Marcie Fleach's final conversation with her former employer Mr. E before she's executed, plays out this way, as all his efforts to stop the evil have come to ruin, and he's going along with the attempt to free it.
Marcie: "E I guess I expected more from you."Mr. E: "So did I little girl, so did I."
- Star Wars Rebels: In "Through Imperial Eyes", this is Lieutenant Lyste's reaction to being framed for treason by Agent Kallus, who he'd had a Villainous Friendship with. What really makes it sting is that the only person who seems to care about Lyste is the same man who framed him, as the look on Kallus' face as Lyste is dragged away suggests it was a choice he wasn't particularly thrilled about making.
- In the Grand Finale of Superman: The Animated Series, Superman is on the run due to attacking Earth while being Brainwashed and Crazy, and Supergirl is badly wounded and needs medical treatment. When he seeks the help of his scientist friend Emil Hamilton who has previously always stood by his side, Emil instead refuses to help because he doesn't want to consort with someone who's a known fugitive. Supes gets so enraged his "friend" is pretty much throwing him to the dogs he winds up threatening to kill Emil unless he helps Supergirl. The Man of Steel quickly winds up being horrified at his actions and softens up, but Emil in turn wins up getting his own Et Tu, Brute moment from this, leading him to switch sides and work with Lex Luthor in Justice League Unlimited.
- Teenage Mutant Ninja Turtles (2003) has it parodied in "Space Invaders Part 3". When Michelangelo once again gloats he is a Battle Nexus Champion, Raphael, who reminded him not to talk about it again, attempts to smack him, but Leonardo stops him... so that he can smack the turtle himself.
Michelangelo: Et tu, Leo?
- When Terra betrays the team in Teen Titans, she is easily able to hunt down and defeat them one by one, because they're unable to fight a former friend using their full strength (save Raven, whom she actually provokes into doing so, which nearly backfires on her). When they do finally let loose, Terra goes down in minutes.
- In The Venture Bros., Monarch says this to King Gorilla when the latter (initially) refuses to help the Monarch escape prison.
- Tangled: The Series: "et tu, Blondie" in episode 7
- A very dramatic example happens in "The Alchemist Returns". Varian, a young alchemist who could find the answers to the black spikes that are ravaging Corona, offers to help Rapunzel by finding the Sundrop Flower that saved her mom. To do so, they have to get it from the Royal Vault. Just as they got there, Varian betrays Rapunzel by taking the Sundrop Flower and reveals his true intentions; he doesn't care about the welfare of Corona and plans to let the rocks destroy the kingdom as revenge for them earlier turning their backs on him when his father got encased in crystal.
- Civil wars are often bloodier than "regular" wars because of this trope.
- There are not any reliable source that Caesar actually said this in real life, but most accounts agrees on that Caesar at first attempted fight off his assassins, but gave up struggling when he spotted Brutus amongst them. According to Roman historian Suetonius, some people said Julius Caesar said something similar, but it was actually in Greek: kai su, teknon? means "You too, my son?" Another Roman historian, Plutarch, writes that Caesar said nothing at all, but he pulled his toga over his head when he saw Brutus among the conspirators.
- Cao Cao had a childhood friend named Zhang Miao. Zhang Miao had a falling out with another of their old friends named Yuan Shao, who at the time was acting as Cao Cao's nominal superior. Yuan Shao asked Cao Cao to execute Zhang Miao for him, but Cao declined to do so. However, when Cao was invading the province of Xu in 194, Zhang Miao (fearing Cao would eventually do as Yuan asked) led a group of conspirators to invite the wandering warlord Lu Bu into Cao's territory and take over.
- The kicker is that Cao Cao was invading Xu in order to avenge his father and brother, who'd just been murdered. While Zhang Miao himself escaped Cao Cao's wrath (by being murdered by his own men), Cao exterminated his family; the usual punishment for treason.
- Oda Nobunaga has had his life full of brutal conquests, other clans conspiring against him and people gunning for his head. He crushed all of them no problem. But when his retainer Akechi Mitsuhide that he trusted for being competent suddenly turned against him at Honnoji, combined with his minimum troops there, Nobunaga instead chose to commit seppuku rather than fighting to the end.