[Cú Chulainn's] son would find him as man
But would not tell his name
So he took a spear to his own child
And doomed himself to shame
But would not tell his name
So he took a spear to his own child
And doomed himself to shame
— Miracle of Sound, "The Tale Of Cú Chulainn"
In the world of fiction, murdering your relatives is considered particularly low. And if it wasn't done out of malice, it is often either a tragic necessity, self-defense, or because their relative was already pretty evil. But not all kinslayings were meant to have that level of gravitas. Sometimes they never intended to "prune" the family tree. However, things still got out of hand.
An unintended kinslayer is someone who either killed their relative by accident or intentionally killed someone but didn't realize they were related until too late. For example, a shoving match between two brothers leads to one of them tripping onto a rock and suffering a fatal head injury, or The Hero kills the Big Bad only to learn too late that they were in fact their long-lost parent or child. This trope is often used for tragedy, as the relative is likely guilt-ridden for life, especially in the case where he knew his victim was related but didn't intend it. With the latter, this is sometimes used to "lighten" the drama that comes with kinslaying. Occasionally you will see subversions where a character is ready to kill someone, only for it to be revealed they're their Long-Lost Relative, preventing them from going through it.
Sub-trope of Murder in the Family. Compare Surprise Incest, where someone sleeps with their relative unintentionally. When someone is tricked into eating their kids unknowingly, it's an example of Familial Cannibalism Surprise. More lethal versions Grandfather Paradox often involve something like this happening, given a time traveler would rarely be looking to retroactively kill their ancestor. If it was a case where the person didn't intend to kill their relative (knowing about their relation or otherwise), it also counts as an Accidental Murder.
Slaying of Kin Unrecognized is the nineteenth of the 36 Dramatic Situations by Georges Polti.
As this is a Death Trope, expect unmarked spoilers below. You have been warned.
Examples:
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Anime & Manga
- The Dagger of Kamui:
- After fleeing his village in the wake of being framed for murdering his adoptive mother and sister, Jiro is taken in by a monk named Tenkai, who has him participate in the murder of a one-armed rogue ninja named Tarouza. However, when Jiro reunites with his birth mother, she reveals that Tarouza is his father and that Tenkai is the one responsible for their family's plight. Naturally, Jiro is left aghast over realizing he was tricked into committing patricide, which is made only worse when History Repeats in that one of Tenkai's agents kills his birth mother and frames him for the act.
- As Jiro sets off to locate the treasure Tenkai was after, one of the assassins that Tenkai sends after him is a kunoichi named Oyuki. After several attempts to kill Jiro, Oyuki briefly makes a truce with him in order to survive their predicament with her reminding him that they will go back to being enemies afterward. While Oyuki eventually pulls a High-Heel–Face Turn, it is revealed that she and Jiro are half-siblings as Tarouza was also her father. However, shortly after this reveal Oyuki is fatally stabbed by Tenkai.
- Dragon Ball: Son Goku's adoptive father/"grandfather" Gohan died by the former stomping on him while transformed into a giant Great Ape. Since he loses his sense of self and control in this form and doesn't remember his rampages, this was entirely unintentional. When he learns about this years after the fact due to witnessing another Great Ape transformation, he's horrified.
- Guyver: In the second half of the series, Sho's father is turned into a Zoanoid by Dr. Balcus. In their ensuing battle, Sho sustains severe damage to his brain, causing him to go berserk before blasting the Zoanoid that was once his father into oblivion using the Megasmasher. Naturally, he's horrified to learn what he had done once he comes to his senses and ends up in a Heroic BSoD that prevents him from transforming. Making matters worse is that he later learns from Makashima that there was no way for him to have reversed his father's transformation and that Mercy Killing him was the only option.
- The Kindaichi Case Files: Near the end of "The Headless Samurai Case", Ryunosuke attempts to poison Shino, his father's second wife to get rid of potential rivals to his fortune. However, Kindaichi later reveals that Ryunosuke is actually Shino's biological son, who was Switched at Birth. Learning this, Ryunosuke tries to stop Shino from drinking the poisoned tea, but it's too late and Shino dies while Ryunosuke can only wail in regret.
- Maya's Funeral Procession: Narrowly avoided; Maya fully intends to kill everyone in the household as a Roaring Rampage of Revenge for the murder of her parents and the disfigurement she and her late sister suffered in the fire set to cover the crime. However, just before she can kill Reina, whom she had also fallen in love with, Reina's mother informs her that Reina is her half-sister because of an affair between Reina's mother and Maya's father, and that his abandoning her when she learned she was pregnant was why she'd participated in the murder in the first place. Maya decides to spare Reina and allows herself to be consumed by the flames of the fire she'd set.
- Mobile Suit Gundam: The Witch from Mercury: In Episode 12, a captive Guel Jeturk decides to escape from the Dawn of Fold's grasp in one of their mobile suits. At the same time, however, his father Vim Jeturk decides to sort it out to combat the threat that the Dawn of Fold poses to himself. What ends up happening is the two fighting one another, with Vim immediately assuming that the MS Guel is in is being piloted by a terrorist, with Guel forced to defend himself. Ultimately, Guel is forced into Killing in Self-Defense, stabbing Vim's Dilanza Sol's cockpit when the latter is off guard. Unsurprisingly, this event traumatizes the young man, not helped by the fact that Vim himself realized too late who his opponent was.
- The Rose of Versailles: Narrowly Averted. Rosalie wants to avenge the murder of her adoptive mother by killing Lady Polignac, whose carriage accidentally ran over her before fleeing the scene of the crime. After being taken under Oscar's wing, she attempts to assassinate Lady Polignac twice but is stopped both times by Oscar, and in the second time around she learns from Oscar that she nearly killed her birth mother.
- Voltes V: To the shock of Prince Heinel, Kenichi, Hiyoshi and Daijiro turn out to be his brothers, as they share the same Boazanian father. Unfortunately, he only finds this out in the Grand Finale, while he was in the midst of slaying Kenichi with his dagger.
Heinel: What... brothers shouldn't be fighting bloody battles!
Comic Books
- Avengers: No Road Home: Spectrum uses a holographic glamour to trick Nyx into killing her own twin children, Apate and Dolos, instead of Hercules and Vision. When Nyx and her resurrected children later reappear in The Immortal Thor, the twins attempt to ensnare Loki with hallucinations, only for Loki to effortlessly see through the trick and use their own, even more formidable, illusion powers to trick Apate into slitting his own brother's throat.
- In XIII, Sean Mullway has a relationship with Carla Giordino and Carla's brother Frank can't stand it. He takes a gun, comes at them and threatens Sean. A fight between the two men ensues and Frank unloads the gun... right in his sister's belly, without intending to. Frank then pins the murder on Sean.
- In The Beast and Snow, Belle set out to kill The Beast to avenge her mother, who had died fighting it. She succeeded, only to learn to her horror that the Beast was her mother, who had become cursed with lycanthropy when she hunted the first Beast. For added horror, the Beast bit her before she died, cursing her with lycanthropy. Later, when Belle's father came to "rescue" her from the Beast, Belle, now mad from the lycanthropy, slew him as well, and didn't even realize it until hours later when she transformed back.
- Hawkworld: In Issue 2, ensign Katar Hol shot a hooded and robbed man believed to be a weapons supplier. But to his horror, it was his father Paran Katar, who's been secretly sending food and medicine to the lower-class Downsiders. He also realized that his corrupt commander Byth Rok knew and goaded Katar Hol into being the fall guy.
- Hound: Cú Cullan fights a duel with a mysterious boy in helmet and armour whose mother has sent him to "kill every dog lover [...] or die trying." Cú Cullan realises that the boy is his only son by Eva upon fatally wounding him.
- The Mighty Thor: Loki, while in the form of a woman, uses his magic to undo a spell he used to kill Bor, a previous king of Asgard and the father of Odin, and unleashes him in the present day where he believes that not only did he lose his final battle but his son was dead. He subsequently goes on a rampage before facing his grandson Thor in battle, and Thor kills his grandfather. As a result, Thor is forever exiled from Asgard for killing a member of the royal family.
- The Sandman (1989), "The Doll's House": Narrowly avoided by Dream when he is dissuaded from killing Rose Walker (identified as the Vortex) by her grandmother Unity Kinkaid, who points out that she would have been the Vortex if Dream hadn't been imprisoned and unwittingly put her (and a number of other people across the globe) into an unnatural and lengthy sleep. Turns out one of Rose's other grandparent is Desire (who seduced and impregnated Unity in a dream while she slept), meaning Dream was about to kill his own grandniece.
- Star Wars (2015): Lampshaded via Dramatic Irony when Luke Skywalker has another narrow escape from Darth Vader sometime between A New Hope and The Empire Strikes Back: Luke comes face to face with Vader and even tells him You Killed My Father, but since Luke never says his name, Vader still has no idea who he is. Vader ultimately learns the young man's surname is Skywalker in issue #6 after Boba Fett also tries and fails to capture him, and determines to take the young man alive and make him his apprentice.
Vader: Who are you?
Luke: You killed my father.
Vader: I've killed very many fathers. You'll have to be more specific. - Wolverine: The "surprise kinslaying" happens to poor Logan twice.
- In his backstory the family's groundskeeper Thomas Logan was a surly and unpleasant drunkard who'd one day invade the Howlett Estate and attempted to take Elizabeth Howlett with him. After shooting James' Howlett/young Wolverine's father John, James' mutant powers activated for the first time and he stabbed Thomas to defend his home. Elizabeth, to her horror, revealed that because of a past affair, the groundskeeper was her son's real father and he was forced to flee the house. For what it's worth, James doesn't regret killing the guy given what he is and considered his legal father his dad where it counts.
- This trope was used by a villain to emotionally break Wolverine. Wanting to avenge his father's death by Wolverine, the Founder would collect a bunch of henchmen he called the Mongrels who he expected to serve as cannon fodder, and right as Wolverine reached them he and his allies would kill themselves so he couldn't get revenge back at them. Then a video recording played revealing his motives, and that the Mongrels were in fact his own long-lost illegitimate children; he had tricked Wolverine into killing several of his own kids as an act of revenge.
Fairy Tales
- "Hop-o'-My-Thumb": Upon realizing that the Giant is planning to kill him and his six brothers while they sleep, the titular protagonist switches his brothers' hats with the crowns of the Giant's seven daughters. In the dark night, the Giant mistakes his daughters for the boys and unwittingly slits their throats.
Films — Animation
- The Lion King (1994): While the audience sees Scar very intentionally killing his brother Mufasa, he frames it in a way to make Simba think he caused his father's death by stampede by accident, pressuring him into running away as an exile out of fear nobody would believe it was an accident... then Scar sics the hyenas on his nephew just to cover his bases. Simba would live with the apparent guilt of his actions until he grows up to face off against Scar, where Simba would learn he wasn't responsible at all.
Films — Live-Action
- The Black Dahlia: Flashbacks show Madeleine Linscott was the culprit dressed as a man in disguise. When she killed Officer Bleichert's friend and partner Lee Blanchard, she unknowingly killed her biological father Georgie Tilden too who was strangling Lee at the time.
- F9: The reason why Dom and Mia never mentioned their younger brother Jakob before is because Dom really doesn't like his brother, stemming from Jakob being the one who sabotaged their father Jack's car brakes, costing him his life in his last legal race. However, as Dom learns later on from Jakob, the truth is more complicated than that: Jack deliberately told his son to sabotage his car so he could lose the next race and claim the compensation money he needed to pay off his family's debts. He also told Jakob not to tell Dom about it, because he knew his older son would not agree to it. Neither Jack nor Jakob knew that sabotaging the brakes would mean Jack wouldn't be able to dodge the car that ploughed into him and sent him crashing to a fiery death, and that accident has haunted Jakob as much as his brother for decades.
- I Still Know What You Did Last Summer: In the climax, Ben Willis accidentally stabs his son Will to death with his hook while trying to attack the heroes.
- Kill List: Jay's final kill is of a hunchback during an Initiation Ceremony of sorts with the cult. He kills the hooded figure and then sees that the figure is of his wife Shel and their son Sammy, who was on Shel's back.
- Legally Blonde: In the Windham murder trial, Chutney Windham is caught in a lie on the stand by Elle, meaning she couldn't have caught Brooke killing her father. This causes a tearful Chutney to blurt out that she killed her father, but only because she was trying to kill Brooke.
Chutney: I didn't mean to shoot him! [points at Brooke] I thought it was YOU walking through the door!
- Manon des Sources: Ugolin and his uncle Cesar spend the whole first film driving their neighbor to his death so they can claim his farmland for themselves. Late in the second movie, it's revealed the man they killed was Cesar's own son, which so devastates him that he simply wills himself to die in the end.
- The Quick and the Dead: In a flashback to Lady's childhood, when Herod is about to hang Lady's father, he says he'll let the man go if Lady can Shoot the Rope, and hands her a gun. Being inexperienced and quite nervous, she hits her father between the eyes, killing him.
- Star Wars:
- Revenge of the Sith: Subverted with Anakin Skywalker/Darth Vader — when he falls to The Dark Side he ends up Force choking his wife, and after his near-fatal duel with Obi-Wan Kenobi, he's told that he apparently killed his wife while she was still pregnant. Having turned in hopes of saving his wife from childbirth, the belief that not only did he kill Padme, but his own unborn child without ever intending to breaks him. In reality, Padme lived long enough to give birth, and to hide the twins, she was buried as if they died with her. Vader only learns he didn't kill his child(ren) about 20 years afterwards.
- The Empire Strikes Back: Luke trains with Yoda to become a Jedi in hopes of stopping Darth Vader and rescuing his friends, with the clear implication he and Obi-Wan Kenobi expect Luke to kill him as they consider him irredeemable. He ends up failing miserably, and Vader reveals he's his father, instead of Luke killing Vader like Obi-Wan intended. In hindsight, it's implied Kenobi and Yoda omitted this fact so that he would be willing to commit unknowing Patricide for the greater good. Needless to say, in Return of the Jedi, he chews Obi-Wan out and is now focused on trying to get to the good inside of Vader instead of offing him.
- Walk Hard: As a young boy, Dewey Cox accidentally cuts his brother Nate in half while they're playing around with their father's machetes.
- Wanted: When Wesley is brought into the Fraternity, he's told by the cell's leader Sloan that Cross, a rogue member, killed his biological father, a comrade of theirs. At the climax of the second act of the film, Wesley fatally shoots Cross, only for him to reveal while dying that HE is Wesley's biological father, and Sloan the real villain of the film.
Literature
- At the end of the Chronique du règne de Charles IX of Mérimée, Bernard de Mergy the main protagonist, who fight in the Huguenot army in La Rochelles, shot at the Royal army and learns too late he had hit his brother George. The last pages are devoted to his agony and his death.
- The Cosmere:
- The Stormlight Archive: Oathbringer reveals that in Highprince Dalinar's Blood Knight days, he had ordered a rebel city burned, unaware that his wife had snuck in to try to negotiate a surrender. It broke him to the point he received Laser-Guided Amnesia, and even after years as The Atoner, the return of the memory nearly drives him over the Despair Event Horizon.
- Wax and Wayne: In the prologue of The Alloy of Law, Wax — a world-class Mage Marksman — shoots at a Serial Killer holding his wife Lessie hostage, only for the killer to pull Lessie into the path of the bullet. The killing derails Wax's life and torments him afterwards, making it all the harsher in Shadows of Self when he learns that Lessie is a Faceless Immortal who staged her death to manipulate him.
- Five years prior to the start of Date A Live, Origami's parents were killed by a spirit, right before her eyes. During the course of the series, she becomes a spirit and convinces Kurumi to send her back to that day to save her parents. While there she encounters the spirit she thinks killed her parents, and in attempting to kill it, she accidentally kills them in front of her younger self's eyes. Needless to say, she does not take it well.
- The Elder Scrolls In-Universe Books:
- "The Mirror
" is about a soldier named Mindothrax whose specialty is fighting defensively until his opponent makes a mistake he can exploit, making them an easy kill. One day, he meets a mercenary named Jurrifax on the battlefield, and is taken aback by the fact that they have an almost identical fighting style, and by how alike they look when Jurrifax removes his helmet towards the end of their duel. Jurrifax takes advantage of Mindothrax's confusion and slays him, and in the aftermath of the battle, tells one of his comrades that he knows he has a Separated at Birth twin brother somewhere in the world and hopes to meet him one day... not realising that he killed him earlier that day.
- "The Marksmanship Lesson" ends with the enslaved archery tutor Dob tricking his pupil Wodilic into shooting Kelmeril Brin, Wodilic's father and Dob's slavemaster, through the neck during one of his practise sessions.
- "The Mirror
- The Elric Saga: The Weird of the White Wolf: During a battle between Elric and Yyrkoon, Elric's cousin Cymoril begs him to stop fighting Yyrkoon because it will cause Elric and Cymoril to be parted. Elric ignores her and keeps on fighting anyway. Yyrkoon throws Cymoril onto Elric's magical sword Stormbringer while Elric is wielding it, killing her.
- "The Hapless Child" is a short story written and illustrated by Edward Gorey. Young waif Charlotte finds herself an orphan, and ends up making lace in a dark, dingy basement as a prisoner of a drunken brute. When Charlotte at last makes an escape, she's almost blind, and can only shamble awkwardly toward her father's voice. Her father, meanwhile, has returned home from abroad, only to learn his daughter has gone missing from an orphanage. The man rides his motorcar through the streets, calling the name "Charlotte," in desperate hope of finding her. When his motorcar bumps into an obstacle in the street, the man finds a tattered and emaciated waif beneath the tyre and fails to recognize his own daughter Charlotte.
- Harry Potter: One of Albus Dumbledore's greatest regrets is that that he may have been an example of this. He, his brother Aberforth Dumbledore, and Gellert Grindelwald were in a wizarding duel and one of the three inadvertently struck and killed Albus and Aberforth's sister Arianna. Nobody knows who fired the killing blow, but Albus and Aberforth would live with the guilt that they might've committed accidental Sibling Murder.
- His Dark Materials: Iofur Raknison, the king of the armoured bears, killed another bear in a fight when he was young, despite fights to the death being taboo to his people unless agreed beforehand. He later discovered that this bear had been his father. Lyra's knowledge of this (via the alethiometer) helps to convince Iofur that her lies to him are true.
- Judge Dee: The Chinese Bell Murders: Lin Fa is an utterly loathsome criminal and businessman who didn't hesitate to backstab his business partner and brother-in-law, rape his sister-in-law (when she committed suicide, he framed it as a suicide after committing adultery), and then have the rest of his in-laws murdered by trapping them in a tower and setting fire to it. Only the widowed grandmother and grandson escaped, and spent the rest of her life chasing Lin Fa around China, trying to get the local judge to retry the case. After the judge condemns Lin Fa to death for entirely different crimes (like, say, the attempted murder of Judge Dee, during which they find evidence that he also murdered someone by trapping them under the titular bell), she stands triumphant in court, trying to say "you killed your-" before fainting. After the execution, the judge learns that the widow killed herself before explaining the Awful Truth to his lieutenants: the widow was Lin Fa's wife, the grandson actually their own son, but she couldn't manage to bring herself to say it, and Lin Fa was executed without knowing what he'd done.
- Mahabharata: Perhaps the most widely known moment from the epic is when Arjuna beheads his Arch-Enemy Karna from behind with his arrow while the latter was struggling to unstick the wheel of his chariot from the mud, which happened due to a curse. However, after the battle, Arjuna's mother Kunti reveals to him that Karna was her oldest child and thus Arjuna's half-brother. Arjuna immediately goes through a Heroic BSoD because he was taught to value family more than anything, and even broke The Laws and Customs of War of his time due to the method he used. He also killed all but one of Karna's sons prior to this, who were his nephews. After all this, Arjuna becomes The Atoner by taking in Karna's remaining son and becoming his Cool Uncle, even leaving him his divine bow.
- A Song of Ice and Fire: In Westeros, killing your own relatives is seen as one of the worst things you can do, alongside breaking guest right. However, this doesn't apply as much if someone is an unintentional kinslayer.
- According to the Free Folk's tales, the King-Beyond-the-Wall Bael the Bard once seduced and impregnated the daughter of Lord Brandon Stark. Their son was then legitimized and eventually became the new Lord Stark. When Bael and this Lord Stark finally met on the battlefield, Bael couldn't bring himself to fight his own son and didn't even try to defend himself. Lord Stark, unaware that Bael was his father, did not hesitate to cut him down and took his head as a trophy.
- The future King Maekar Targaryen was jealous and resentful of his older and more popular brother Baelor "Breakspear", though not to the point he ever considered fratricide. Tragically during a Trial by Seven where the two would tussle, a poorly timed strike of the mace causes Maekar to deal a fatal blow to Baelor. Though this was an accident that haunts him for the rest of his life, it doesn't stop it from permanently staining his reputation and unfounded rumors that it wasn't an accident from spreading (not helped by Baleor being the heir apparent while he was alive).
- Historically, Prince Aelor Targaryen would die at the hands of his twin sister Aelora, and while it's not known why, it's stated to have been a mishap. Aelora clearly didn't mean to cause it because they were married and she would be Driven to Suicide due to her grief. This was one of many tragedies that eventually led to the aforementioned Maekar becoming king despite being low in the initial line of succession.
- The Shahnameh: Rostam ends up fighting against his son Sohrab, respectively, and due to Poor Communication Kills doesn't find out how they're related until he's already lethally stabbed his sons. Cue My God, What Have I Done? moment.
- Splinter of the Mind's Eye: In this Star Wars book, written before the fifth and sixth episodes (where it's revealed that Darth Vader is Luke and Leia's father), Leia tries to kill Vader by shooting him from ambush. Later, Leia and Luke fight Vader with lightsabers. Vader survives, but loses his arm and falls into a bottomless pit. Luke and Leia also survive, but they are incredibly badly injured. In fact, Luke believes that they did die, but came Back from the Dead thanks to the Force and the Kaiburr crystal. This book became part of the Star Wars Legends, but the events were retconned. In the book The Rise and Fall of Darth Vader, it was revealed that Vader originally wanted to capture Luke and Leia, not kill them. At that time, Vader already knew Luke's last name and assumed that he could be his son, but didn't know for sure (but he had no idea that Leia was his daughter, Luke and Leia also didn't figure anything out). However, the influence of the Kaiburr crystal increased his hatred, and it all ended in a duel to the death.
- Tolkien's Legendarium: A late version of the story of Fëanor and the Noldor's exile to Middle-earth (given in The History of Middle-earth but not taken up into the published Silmarillion by J. R. R. Tolkien's son Christopher) tells that, when Fëanor ordered his stolen ships burned, he unwittingly killed his son Amrod, who was still on board one of the ships, asleep. In the tale as published, Amrod dies much later in the Third Kinslaying.
- Warrior Cats: Firestar killed Scourge without ever knowing that Scourge was his half-brother on his father's side.
- The Wheel of Time: The Eternal Hero Lews Therin Telamon became known to history as "the Kinslayer" for killing his entire household in a mad delirium inflicted by the Dark One. When granted a Moment of Lucidity to realize what he had done, he killed himself.
- In the first Wings of Fire book, Tsunami is trapped in the SkyWing's gladiator arena and is forced into battle against a delirious, dehydrated SeaWing. Much to her horror, she's forced to kill him to survive but tries to think of it as a Mercy Kill given how terrible his condition was. In the second book, however, she learns that this SeaWing was her father, and a missing king and diplomat to boot, leaving her deeply distressed.
- Wizard and Glass: After capturing the wizard's glass from Flagg, Roland shows his ka-tet the secret waiting inside it: He confronted the witch Rhea in his mother's bedchamber and shot her, only to discover it was one of Rhea's illusions, and he was tricked into killing his own mother.
- The Worst Thing About My Sister: Subverted: Marty accidentally knocks her sister Melissa out during a squabble on a top bunk, which makes Marty worry that she has killed Melissa and is thus a murderer. As it turns out, though, Melissa is alive.
Live-Action TV
- Blackadder: In "The Foretelling", Edmund angrily beheads a helmeted man whom he'd caught stealing his horse, then discovers it was his great-uncle Richard, to his horror. Not so much for the kinslaying, though, as the fact that Richard was also the king, and Edmund will be in big trouble if anyone finds out he killed him. (Although the second episode reveals that Edmund is almost certainly a bastard, meaning they weren't actually biologically related.)
- CSI: NY: In the episode "And Here's To You, Mrs. Azrael", the CSIs investigate the death of a young woman who was killed in her hospital bed. The investigation reveals that she and her best friend, who looked similar to one another, that they could pass for sisters or twins, had been partying and got into an accident where one of the girls was killed due to the other drinking and driving. Once they gather all the evidence, the CSIs' conclude that a nurse at the hospital, the mother of one of the girls, killed her own daughter when the girls were misidentified.
- Game of Thrones: Inverted with Joffrey Baratheon. Unlike in the books, where it was Cersei's orders, Joffrey orders the death of old King Robert's bastards in hopes of quashing rumors about his paternity. Since he's convinced said rumors are untrue from his perspective, he's ordering the death of his own half-siblings, but he dies never realizing he's not Robert's actual kid and thus wasn't related to them.
- Hannibal: Lawrence Wells ended a 40-year streak as a Serial Killer by murdering the son of his first victim, his mistress's husband. He saw it as the culmination of his legacy, only to have a Villainous BSoD upon learning that he himself was the son's biological father.
Will Graham: You thought the woman you loved was having Fletcher Marshall's baby when she should've been having yours, but you got it the wrong way around! Eleanor chose to raise him as Fletcher Marshall's child rather than yours, so maybe... she saw what's in your heart.
Jack Crawford: You didn't secure your legacy, Mr. Wells. You murdered it. - House of the Dragon: In the Season 1 finale "The Black Queen", Aemond Targaryen chases his nephew Lucerys Targaryen with their dragons in order to intimidate him, however he ends up losing control of his dragon Vhagar who eats Lucerys and his dragon Arrax. While he hates his nephews he never intended to kill them and is lost in shock after it happened. This is a change from the source material, where the kinslaying was very much intentional.
- On NCIS, Gibbs and Vance manipulate a situation so that a corrupt Mexican official mistakenly kills his sister, the head of a drug cartel.
- In Star Trek: The Original Series episode "The Conscience of the King", mass-murderer Kodos is disguised as an actor. His daughter, who found out his real identity, has started killing off those who could identify him; however, when she tries to kill Captain Kirk, her father gets in the way of the phaser shot and dies.
- The Wheel of Time (2021): "Leavetaking" gives Perrin an Adaptational Angst Upgrade in the form of a pregnant wife whom he accidentally kills: in a desperate fight against Trollocs, he hears movement behind him and takes a blind swing with his axe, striking her in the chest.
- On Westworld, after the host rebellion, Delos majority-holder William meets up with his daughter (who was vacationing in another world at the time). He believes that she is really a host sent by the original owner Robert Ford to torment him. When she repeats to him a piece of information that she couldn't have known (but Ford could), he shoots her dead. Then, he finds she is carrying the data card from William's exploits in the park that caused her mother to commit suicide. William, effectively, killed both his wife and daughter.
- The White Lotus (Season Three): Rick has an axe to grind against Jim Hollinger, as he thinks Jim killed his noble father. He only finds out that Jim was his father after shooting the man dead.
Music
- The Mechanisms: "Ulysses Dies At Dawn," being based on Classical Mythology, has Oedipus kill the man he doesn't know is his father when he tries to stop his research into curing a fatal illness, since discovering the cause of it will get him on the Olympians' list.
- Miracle of Sound: "The Tale Of Cú Chulainn" describes how the eponymous hero of Celtic myth killed a man who refused to tell him his name, which would have let him realize the man was his own son.
Mythology & Religion
- Arthurian Legend: Sir Balin and Sir Balan are brothers. Balin becomes known as "The Knight of Two Swords" due to winning a sword through a feat of chivalry but is warned that if he continues to wield both swords he will bring about disaster to himself. During a journey, he approaches a castle and is met by an unfamiliar knight, who bids him to seek shelter elsewhere. Offended, Balin threatens the knight, who likewise threatens to kill him if he insists on proceeding. In the resulting fight, both knights fatally wound each other, and it's only then that the mystery knight realises Balin is carrying two swords and reveals himself as his brother Balan.
- Celtic Mythology:
- Cu Chulainn ends up fighting against his son Connla, and due to Poor Communication Kills (and a geas on the part of Connla), he doesn't find out how they're related until he's already stabbed him to death with the Gae Bolg. Cue My God, What Have I Done? moments.
- Subverted In one Fionn Mac Cumhaill story. After a bad argument with his father, Fionn's son Oisin temporarily strikes out on his own until things cool down. Eventually Oisin starts making his way back home while in disguise and runs into Fionn who, coincidentally, is also disguised. The two wind up in a fight with each other that seems to be building up to one killing the other. However, father and son recognize each other mid-battle, immediately drop their weapons and embrace, happy to be reunited.
- Goll Mac Morna of The Fianna gets in a dispute with one of the other members (either Oscar or Oisin) over who should get the champion's portion at a feast. (The champion's portion is a special part of a feast reserved for the most prestigious warrior.) To settle this, they hold a marrow-sucking contest. Goll loses and, in a fit of anger, throws the bone at Oscar/Oisin, who dodges. Unfortunately, Goll's aged mother is in the path of the bone as it sails across the room and strikes her in the head, killing her.
- Classical Mythology: Most of the time when someone tries to kill their relative because of a prophecy they would do so, it motivates said relative to kill them anyway. This isn't the case for Perseus; his grandfather Acrisius tried and failed to get rid of him and his mother. While Perseus does kill him, it's completely by accident; he throws a discus at a funeral game and it hits Acrisius in a freak accident. Thus proving You Can't Fight Fate even when Perseus couldn't care about said fate.
- Norse Mythology: The otherwise-invincible Balder is killed after Loki tricks his blind brother Hod into throwing a sprig of mistletoe at him. As it happens, mistletoe was the one thing against which Balder had no immunity.
Theatre
- Blood Brothers ends with Mickey confronting Eddie after finding out that Eddie has been carrying on an affair with his wife. Enraged at the prospect that his daughter might not be his, Mickey aims a gun at Eddie demanding to know when the affair started. During the confrontation, Mickey's mother shows up and tells Mickey that he can't shoot Eddie because Eddie is actually his twin brother. During the shock, Mickey accidentally pulls the trigger, killing Eddie, then is shot himself by the police.
- Euripides: This is a favored trope of the most famous playwright of Athens.
- Bacchae: Pentheus, the King of Thebes, is torn apart by Dionysus' crazed followers as a punishment for banning his worship in Thebes. Among Pentheus' killers is Agave, his own mother, as well as some of his aunts, who have all been enchanted to believe that they killed a mountain lion. They don't realize what's happened until after they bring their "trophies" to Agave's father Cadmus, who is suitably horrified at the sight of his grandson's torn body.
- Heracles: On orders from Hera, who wants revenge on Zeus for cheating on her with Heracles's mother, Iris enchants Heracles to make him believe his wife Megara and their three children are the family of Eurystheus, the king who assigned him his Twelve Labors. Thinking to get payback for all the (at one point literal) crap Eurystheus put him through, he murders them. He's knocked back to his senses by Athena and goes into exile in Athens in shame.
- Peliades: The sorceress Medea tricks the daughters of King Pelias by offering to teach them a spell that can make the old young again and demonstrates the spell's power by conducting an illusion on which she butchers an elderly ram, places its remains in a cauldron and pulls out a newborn lamb. The daughters then decide to murder their father in order to try the spell on him, only to realise too late that the spell isn't real.
- Oedipus the King: This is famously one half of the tragedy, the other being Surprise Incest. Learning a prophecy that he is destined to kill his father and marry his mother, Oedipus leaves his adoptive parents to avoid this, and on his travels ends up killing a man who turns out to be the king of Thebes, Laius. He eventually marries his widow, only to learn that Laius and the queen Jocasta were his biological parents... meaning he killed his father and married his mother after all. Ironically, Laius abandoned him to eventually be found by his adoptive parents to prevent the prophecy from happening.
- Sweeney Todd: The Demon Barber of Fleet Street:
- Sweeney almost murders his own daughter Johanna due to not recognizing her and wanting to get rid of a witness to his vengeance against Judge Turpin.
- Near the end of the play, Todd kills the beggar woman who had been appearing all throughout the play, only to later discover that the woman in question was his wife Lucy, who he believed to be dead after he was told she had poisoned herself. Finding out the truth pushes him over the Despair Event Horizon, as he subsequently murders Mrs. Lovett for withholding the full truth from him before letting Toby kill him with his own razor.
- In the finale ultimo of Il trovatore, the Count executes Manrico. Azucena then reveals to him that he has just killed his brother, and triumphantly adds that her mother has been avenged.
Video Games
- Castlevania: Lords of Shadow – Mirror of Fate: Dracula kills his son Trevor who was trying to slay him, not knowing that Trevor is his son. Upon being informed of their blood relation, Dracula revives Trevor as a vampire.
- Crusader Kings II: An event as a Satanist in Monks & Mystics allows you to attempt to murder a rival by using them as a Human Sacrifice in a bronze bull. One possible outcome is for your rival to turn up alive afterward, having replaced themselves with one of your family members.
- Final Fantasy Crystal Chronicles: The Black Knight is a warrior suffering from Identity Amnesia and on a quest to destroy the monster that stole his memories, and is prone to Berserker Rages that make him a danger to those around him. Leon Esla is a young Lilty who has sworn vengeance on the knight, believing him to have killed his father. When the two eventually meet, Leon impales the knight with his spear, and the Black Knight has a moment of clarity just before his death, his last words implying that Leon and his mother are his son and wife. Leon then takes the knight's helmet to display as a trophy in his home but notes that his mother gets upset whenever she has to walk by it.
- Fire Emblem Gaiden: Alm leads the Deliverance in a war that ends with killing Emperor Rudolf. With his dying breaths, Rudolf reveals that he is Alm's father, and he deliberately masterminded a Thanatos Gambit so that Alm would slay him. Alm is understandably anguished by the news that he unknowingly committed Patricide, especially in the expanded story of the remake Fire Emblem Echoes: Shadows of Valentia.
Alm: No, wait! Emperor Rudolf! Were you truly my father? Then I've just... Oh, gods... What have I done? Aah... AAAAAAAUGH!
- Fire Emblem Fates: In the Birthright route, Xander accidentally kills his sister Elise when she took the slash meant for the Avatar. His horror and devastation over this leads him to Suicide by Cop at the Avatar's hands.
- Five Nights at Freddy's:
- Five Nights at Freddy's 4: This, alongside Deadly Prank, is the fate of the protagonist. "The Crying Child" is bullied by his brother and takes advantage of his fear of Freddy Fazbear to stuff him in the Fredbear animatronic's mouth to scare him. He didn't expect the animatronic to clamp down and mortally wound his brother, eventually leading to his death and said brother's immense guilt.
- Five Nights at Freddy's: Sister Location: William Afton created the Sister Location's animatronics with the added purpose of being Homicide Machines meant to abduct and/or kill children for him. His daughter Elizabeth ends up getting too close to one of them, Circus Baby, whose murderous programming activates and kills her. While William is a child Serial Killer he legitimately didn't intend her to be one of their victims since he (maybe) actually cared about her. Ironically, she was the only known victim of these animatronics.
- God of War:
- In the first two games, Kratos kills Ares to take revenge on his former master for tricking him into murdering his wife and daughter, then goes on to kill Perseus and stab Athena to death (that last one was by accident since he was trying to stab Zeus and she got in the way), only for the dying goddess to reveal that he's a son of Zeus, and therefore her half-brother, along with Ares' and Perseus'. Of course, despite regretting killing Athena, Kratos being a dangerously stubborn vengeful man, insists on continuing to pursue revenge against Zeus, to the point that he's willing to intentionally kill any family members who stand against him. Two other games reveal that Kratos had killed three other divine and semi-divine half-siblings before going after Ares, in his sister Persephone and his brothers Castor and Pollux, though given that all of them were villains and trying to kill him, he can be forgiven for not holding back.
- God of War (PS4): One of the stories Mimir tells is of the tragedy of Skadi. After she rebuffed Odin's advances, he retaliated by telling her about an eagle that was stealing the Aesirs' apples. When Skadi hunted down an shot the eagle, she discovered that it was her shapeshifting father. Horrified and grief-stricken over what she'd done, she cradled her father's corpse and let the mountain cold take her.
- Injustice:
- The plot is kicked off by the Joker kidnapping a pregnant Lois Lane and using kryptonite-laced fear gas to make Superman think she's his enemy Doomsday and throws "him" in space, only realizing too late he killed his wife and unborn child...and Metropolis since the Joker set up a nuclear bomb triggered by her heartbeat stopping. This serves the Injustice Superman's Start of Darkness, starting with shoving his hand through the Joker.
- One of the major factors behind Bruce and Damian Wayne's estrangement, asides from the latter's agreement with Superman's policies, was that he unintentionally caused Dick Grayson/Nightwing to lose his balance by knocking his baton at him, leading to him breaking his neck on a rock. Like the source material, they're siblings by way of adoption.
- OMORI: The Reveal is that Sunny accidentally pushed his sister Mari down the stairs following a heated argument with her and killed her, subsequently alongside his friend Basil staging it as a suicide. Needless to say, by the time the game starts the guilt of the incident is so strong that Sunny and Basil are outright suicidal themselves.
- Soul Edge: Siegfried, a young noble, joined the bandit clan Schwarzwind. During an ambush, he kills a knight, who turns out to be his father, leading Siegfried down a dark path until he eventually finds redemption and reforms Schwarzwind as a group of soldiers who can be hired rather than just thieves.
- Twisted Metal: Yellow Jacket's ending has its driver, Charlie Kane, go to Calypso for information on his missing son. Calypso then informs him that his son, Needles Kane, was driving the ice cream truck (Sweet Tooth) that Charlie destroyed in the tournament, killing his own son.
Visual Novels
- Danganronpa: Trigger Happy Havoc: In the second Class Trial, it is revealed that Mondo's secret is "Mondo killed his own older brother." However, as Monokuma tells the story of how it happened—Mondo challenged his brother to a street race, becoming reckless, and the brother performed a Heroic Sacrifice to save Mondo from being hit by an oncoming truck—it becomes clear that it was entirely an accident.
- Phoenix Wright: Ace Attorney: Subverted. When Miles Edgeworth was a kid, he tossed a gun in hopes of saving his father only for the gun to go off and shoot somebody. For years, Miles assumed that he killed his father. However, during a trial where he stands as the defendant, Phoenix reveals that he is innocent and that Manfred Von Karma was the one who killed Miles's father along with being the one who Miles unintentionally shot when he lets out a scream just like the one Miles heard.
Web Animation
- Helluva Boss: As detailed in a flashback, during a party for Fizzarolli, Blitzo ends up leaving in heartbreak while accidentally knocking over a lit cake that sets the entire circus on fire. Among those killed in the fire is Blitzo's own mother, which is a fact that continues to haunt Blitzo who understands he is the reason she died.
- Squimpus McGrimpus: This Five Nights at Freddy's Analog Horror takes the interpretation that the Crying Child is Michael Afton's brother, and that out of jealousy for being their father's favorite caused his brother's unintended death. William despises Michael for this and claims he did it intentionally (something the child's vengeful spirit agrees with for a time). William went on to kill children to satiate his rage at Michael since if he killed him he'd definitely be caught (though it's hinted he already wasn't a good father to him before this).
Webcomics
- One-Punch Man is challenged by Oldface and Beefcake, who go by the moniker Brain and Brawn Brothers. Oldface rants and raves at Saitama about his accomplishment, turning his muscular brother into a hulking, towering giant. When Saitama seems unfazed, Oldface commands his brother to squish Saitama, who's standing on his right shoulder. Beefcake instead squishes the man on his left shoulder, who happens to be Oldface. When Beefcake inspects his palm to assess his handiwork, he recognizes the mushy remains of Oldface, and cries out "Misa!" (brother in Japanese).
- The Order of the Stick: One of Eugene's magical experiments went awry, resulting in the death of his son Eric.
- Unsounded: Nary shoved his wife off a dock when she was trying to throw their infant daughter into the sea to drown her. He wasn't trying to kill her but the waters were infested with waterwomen which ensured she had no chance to get herself back to shore. He doesn't seem overly upset by it, only lamenting his choice on a few drunken occasions when he thinks it would have been better for his strange child to have died instead.
- Widdershins: Narrowly avoided in Chapter 8. The Arc Villain tries to dispose of Vincent by leaving him in place of a condemned prisoner about to be hanged, already gagged and hooded. The Executioner is Vincent's father. It's foiled in time, but the father retires immediately.
Western Animation
- Blood of Zeus: Seraphim murders Heron's mother, Electra, in front of him to instill the same rage he carries unaware that Electra was his mother as well. Finding this out causes him severe anguish and furthers his hatred of the gods.
- Futurama: A near-example happens in "Leela's Homeworld" where Leela is briefly convinced that the two hooded and robed mutants killed her real parents and were making some sort of Stalker Shrine. Fortunately, before she can fire at them, Fry shows up and decloaks them, revealing they are her parents, and preventing Leela becoming an orphan all over again.
- Miraculous Ladybug: In "Destruction", Cat Noir accidentally uses Cataclysm on Monarch, giving him a fatal wound that causes the latter's body to slowly disintegrate over the rest of the season. In the season finale, as Gabriel Agreste succumbs to the wounds, he extracts a promise from Marinette Dupain-Cheng that she will never tell his son that he was Monarch. Marinette readily agrees, knowing that it would destroy Adrien if he ever found out that he killed his own father.
- South Park: As part of his revenge for his parents being turned into chili and tricked into eating them in "Scott Tenorman Must Die", Scott in "201" would reveal that the prior statement Lianne was actually a Hermaphrodite and Eric Cartman's "father" was a lie meant to cover the fact his father was a Denver Bronco and they didn't want to ruin their good season with an infidelity. Said Denver Bronco was also Scott's father, meaning Cartman committed Patricide without knowing it. Cartman afterwards is devastated...by the fact it means he's half-ginger. He later finds peace that it also makes him half-Denver Bronco.
- Xavier: Renegade Angel: The first season of the show revolves around Xavier trying to find his father's killer. In the season finale, he finds out he was his own father's killer, as he accidentally burnt their house down when he was younger.
