History Main / CainAndAbelAndSeth

* In ''VideoGame/MortalKombatArmageddon'' Rain's Ending [[spoiler:it is revealed he is the third son of Argus - the other two being rivals Dagon and Taven]]

* ''LightNovel/DateALive'' has Shido and Kotori (the former being adopted into the latter's family) suddenly encounter the former's younger biological sister Mana one day. What makes this complicated is that ''both'' Shido and Mana have amnesia and don't remember their pasts. Mana does have a locket containing a picture of her and Shido when they were younger, which is how she recognises him when she coincidentally sees him in a video. The relationship is confirmed by DNA testing. The drama comes from the fact that Kotori is part of the organisation Ratatoskr, which seeks to control Spirits by making use of Shido's ability to seal their powers, while Mana is part of DEM, which tries to kill them, and she doesn't appreciate Kotori putting Shido at risk.

* Played about as straight as it can be with Cain (the BigBad), Abel (TheHero), and (TheHighQueen) Seth from ''LightNovel/TrinityBlood''. Each also [[SpellMyNameWithAnS spells their last name differently]] to reflect their different personalities and roles.

* The D&D setting of ''TabletopGame/{{Ravenloft}}'''s OriginStory features the CainAndAbel story of how Strahd was driven by jealousy to murder his youngest brother Sergei, becoming a vampire for his crimes. Little attention has ever been given to Sturm, the middle brother, even though he's the only one of their family who survived to become the ancestor of all living Von Zaroviches.

* Played about as straight as it can be with Cain (the BigBad), Abel (TheHero), and (TheHighQueen) Seth from ''LightNovel/TrinityBlood''.

* Cain and Able being major players in the universe of the ''Wiki/SCPFoundation'', it's of course inevitable that their family shows up from time to time.

* In ''Manga/OnePiece'', Luffy and Ace are revealed [[spoiler:to not be related, and have a third [[BloodBrothers Blood Brother]] named Sabo. In their youth, he was the physical midpoint of the three and was TheSpock in their three-man band. The story is told entirely through flashback, as Sabo is assumed dead and thus a PosthumousCharacter. His death and Ace's subsequent death]] complicates every ''previous'' interaction between Luffy and Ace, their current situation, and [[GallowsHumor all those that would follow]]. Additionally, Ace's tattoo and Luffy and Ace's relationships with their TrueCompanions take new significance. In a cover, it is shown that [[spoiler:had Sabo lived, the three would be together, and to cement this "Good Future", Ace's tattoo loses its meaningful misspelling. It becomes further complicated when it's revealed that Sabo ''survived'' the incident that supposedly took his life, and has been in hiding for the last twelve years, apparently as a member of the Revolutionary Army. While undoubtedly a heartwarming revelation, it becomes HarsherInHindsight when one realizes that Ace died without ever knowing that his other brother was alive. And even moreso because Sabo had amnesia the whole the time, only remembering his life with Ace and Luffy upon learning of Ace's death... at which point he collapses in tears because he wasn't there to even attempt to save his brother.]]

* Marvel’s ''ComicBook/{{Eternals}}'' have Kronos and Uranos, the first leaders of the million-year old Eternals, who fought a bloody civil war over the future of the Earth. The genocidal Uranos lost; Kronos himself fell from grace many thousands of years later. Both are now supposedly [[SealedEvilInACan imprisoned forever]]. But then there’s [[TheUnseen their brother Oceanus]], who’s still active and alive, but has been staying out of Eternal politics for a very long time.

* In ''ComicBook/XMen'', a slip up by Mr. Sinister introduced an example. As explained on the TangledFamilyTree page, Scott Summers was introduced as an orphan, then met and established a relationship with his brother Alex. This lasted for quite some time before Sinister hinted that there was at least one more brother out there. After a lot of plot changes and WordOfGod statements, the brother was set as Vulcan, a supervillain emperor. But of course, given that Sinister never gave a specific number (he merely said "brothers"), any or all of the other implied candidates could still ''also'' be Summers brothers.

* The third installment of ''ComicBook/AmeliaRules'', "Superheroes", uses the trope namer. According to Reggie, the very first Steve in the Legion of Steves was the third brother of Cain and Abel who has been lost to history. Steve manipulated Cain into instigating conflict with Abel, before shifting blame back to Cain saying "You shouldn't have done THAT!" when Abel died. [[spoiler: Turns out to be made-up, though, since the Legion of Steves was just Kyle's way of getting back at his mom's new boyfriend.]]

* ''Series/GossipGirl'', where Chuck becomes Serena and Eric's adoptive brother when their parents are married. The siblings already knew Chuck, and because of his earlier attempt to rape Serena, neither of them trust him. While Eric is the first to come closer to Chuck, Serena still distrusts him and blames him for sending her porn magazines. [[spoiler: Though, as it turns out, they were sent by someone else. Their relationship gets even worse when Chuck's father dies]].

* Venus de Milo of the short-lived ''Series/NinjaTurtlesTheNextMutation'' series was a female turtle with the same MetaOrigin. But she got so much hate from the [[FanonDiscontinuity fans]] ''[[DisownedAdaptation and creators of the original series]]'', and the show got terrible ratings and was cancelled, so the whole thing is [[CanonDiscontinuity noncanonical]] now.

** When Adam eventually makes another appearance in season five [[spoiler: as himself, after he's been [[BackFromTheDead brought]] back [[BackForTheDead from the dead]] as bait or a [[TakeAThirdOption possible alternative]] for Michael,]] he doesn't get along with either of the brothers that never knew about him. In Season six, when Dean's given the option to either [[spoiler:save Sam's soul from eternal torment in Lucifer's cage or rescue Adam's from the same place, Dean [[BigBrotherInstinct unsurprisingly]] doesn't even hesitate in choosing [[{{Protectorate}} Sam]]]].
** Simultaneously, within the archangels, [[ArchangelLucifer Lucifer]] and [[ArchangelMichael Michael]] are seeking the same Armageddon, each thinking they would win. Winchester brother intervention gets [[ArchangelGabriel Gabriel]] involved, introducing this dynamic between them to the viewers. Gabriel takes neither side, choosing ''humans'' instead, and is responsible for [[spoiler: telling Sam and Dean how to seal the both of them in Lucifer's Cage, preventing the conflict that would raze the world]].

* ''VideoGame/{{Blazblue}}'' have Ragna, Jin, and their sister Saya. Saya was kidnapped 10 years before the start of the story and is nowhere to be seen in the present, both Ragna and Jin assuming that she was long dead. [[spoiler: The ending of the second game came and revealed that she was very much alive and now the head of TheEmpire subjugating the world, additionally she's also possessed by a death god. So both brothers have to put aside their own animosity for each other and deal with their sister.]]
* ''[[VideoGame/FirstEncounterAssaultRecon F.E.A.R.3's]]'' [[spoiler: Third Child]] is hinted in the good ending to have a brighter future than [[spoiler: its brothers.]]
* ''VideoGame/FireEmblemGenealogyOfTheHolyWar'' ends up with a showdown between [[spoiler: protagonist Seliph and his half-brother and half-sister Julius and Julia. Depending on the player's actions, Julia can either be an enemy or ally.]]
** Though in all honesty, [[spoiler: Seliph inverts this, as Seliph is both the Seth and the oldest, and is also their half-sibling instead of full. Making Julia the Abel.]]
* In ''VideoGame/MetalGearSolid'', established character Solid Snake meets his twin clone brother, Liquid Snake. Designate Cain or Abel to whichever one you want (Liquid claimed that one of them was the brother of light, and one is the brother of dark, but he didn't care to specify who was who) however, Snake was the one who survived and Liquid was killed by [[spoiler: the FOXDIE disease carried by Snake.]] However, [[spoiler: as TheStinger in ''VideoGame/MetalGearSolid'' alluded to, there was a third "Snake brother", Solidus Snake. He shows up in ''VideoGame/MetalGearSolid2SonsOfLiberty'' as Raiden's primary antagonist, not Snake's.]] Interestingly, while the three brothers find themselves on opposing sides, they are all generally considered to be [[WellIntentionedExtremist Well-Intentioned Extremists]].
* In ''VideoGame/MortalKombatArmageddon'' Rain's Ending [[spoiler: it is revealed he is the third son of Argus - the other two being rivals Dagon and Taven]]

* ''VideoGame/XenobladeChronicles2'' has a subversion with [[ApocalypseMaiden Pyra/Mythra]] and [[BigBad Malos]], who while not fully siblings, are considered to be as such and have a CainAndAbel dynamic. Near the end of the game, it is revealed that [[spoiler: Pyra/Mythra and Malos were once two of the three cores of the Trinity Processor, which powered a supercomputer that awakened [[TheMonolith the Conduit]]. Pyra/Mythra was originally named Pneuma, and Malos was originally named Logos. However, the missing third core of the Trinity Processor, Ontos, is nowhere to be seen, as the Architect mentions that Ontos triggered a space-time transition event and [[LongLostSibling disappeared into another dimension]]. Though due to the Architect actually being Professor Klaus from [[VideoGame/XenobladeChronicles1 the first game]], Pyra/Mythra having [[CombatClairvoyance Foresight]] as one of their abilities, and Malos wielding a Monado as his weapon of choice, players who have played through the first game can connect the dots easily to infer that Ontos [[CanonCharacterAllAlong is actually Alvis/the Monado]] from the first game. Sure enough, when ''[[UpdatedRerelease Xenoblade Chronicles: Definitive Edition]]'' was released, Alvis' model was changed to have him bearing a red core crystal in the same shape as Pyra/Mythra and Malos' core crystals.]]

* ''Series/{{Gossip Girl}}'', where Chuck becomes Serena and Eric's adoptive brother when their parents are married. The siblings already knew Chuck, and because of his earlier attempt to rape Serena, neither of them trust him. While Eric is the first to come closer to Chuck, Serena still distrusts him and blames him for sending her porn magazines. [[spoiler: Though, as it turns out, they were sent by someone else. Their relationship gets even worse when Chuck's father dies]].

* ''[[VideoGame/FireEmblemJugdral Fire Emblem: Genealogy of the Holy War]]'' ends up with a showdown between [[spoiler: protagonist Seliph and his half-brother and half-sister Julius and Julia. Depending on the player's actions, Julia can either be an enemy or ally.]]

* The third installment of ''ComicBook/AmeliaRules'', "Superheroes", uses the trope namer. According to Reggie, the very first Steve in the Legion of Steves was the third brother of Cain and Abel who has been lost to history. Steve manipulated Cain into instigating conflict with Abel, before shifting blame back to Cain saying "You shouldn't have done THAT!" when Abel died. [[spoiler: Turns out to be made-up, though, since the Legion of Steves was just Kyle's back at his mom's new boyfriend.]]

[[folder:Comics]]

[[folder:Films - Live-Action]]

[[folder: TabletopGame]]

* In ''Manga/OnePiece'', Luffy and Ace are revealed [[spoiler:to not be related, and have a third [[BloodBrothers Blood Brother]] named Sabo. In their youth, he was the physical midpoint of the three and was TheSpock in their three-man band. The story is told entirely through flashback, as Sabo is assumed dead and thus a PosthumousCharacter. His death and Ace's subsequent death]] complicates every ''previous'' interaction between Luffy and Ace, their current situation, and [[GallowsHumor all those that would follow]]. Additionally, Ace's tattoo and Luffy and Ace's relationships with their TrueCompanions take new significance. In a cover, it is shown that [[spoiler:had Sabo lived, the three would be together, and to cement this "Good Future", Ace's tattoo loses its meaningful misspelling. It becomes further complicated when it's revealed that Sabo ''survived'' the incident that supposedly took his life, and has been in hiding for the last twelve years, apparently as a member of the Revolutionary Army. While undoubtedly a heartwarming revelation, it becomes HarsherInHindsight when one realizes that Ace died without ever knowing that his other brother was alive. And even moreso because Sabo had amnesia the whole the time, only remembering his life with Ace and Luffy upon learning of Ace's death...at which point he collapses in tears because he wasn't there to even attempt to save his brother.]]
* ''Anime/YuGiOh'': In the anime, the Virtual World FillerArc stars Noah Kaiba, the previously-unknown biological son of Seto and Mokuba's adoptive father. He has an enormous grudge against Seto and wants to take away everything he has--including Mokuba, who he kidnaps and brainwashes into thinking Noah is his only brother. The brainwashing doesn't hold, but after Noah has a HeelFaceTurn Mokuba says that he's family.
* Played about as straight as it can be with Cain (the BigBad), Abel (TheHero), and (TheHighQueen) Seth from ''LightNovel/TrinityBlood''.

* In ''ComicBook/XMen'', a slip up by Mr. Sinister introduced an example. As explained on the TangledFamilyTree page, Scott Summers was introduced as an orphan, then met and established a relationship with his brother Alex. This lasted for quite some time before Sinister hinted that there was at least one more brother out there. After a lot of plot changes and WordOfGod statements, the brother was set as Vulcan, a supervillain emperor. But of course, given that Sinister never gave a specific number (he merely said "brothers"), any or all of the other implied candidates could still ''also'' be Summers brothers.

* The ''WesternAnimation/AvatarTheLastAirbender'' continuation comics have Zuko and Azula's maternal half-sister Kiyi, who complicates their already complicated relationship by having a remarkably uncomplicated one with Zuko, adoring and admiring him. Meanwhile, Azula initially takes her entire existence as an insult, thinking Ursa had her as a replacement because Azula disappointed her (this isn't even remotely true, but Azula's grasp on reality post-series is tenuous at best). In Kiyi's second appearance, Azula expresses some mild admiration for her, but that's all.

* Reality show ''Series/TheOsbournes'' featured Ozzy Osbourne, his wife Sharon, and their children Kelly and Jack--but not their oldest, Aimee Osbourne, who refused to participate. Reportedly she stayed in the guest house when MTV was there filming.
* In ''Series/{{Supernatural}}'', Sam and Dean have spent most of their twenty-some years with only each other as dependable family. Eventually, in the episode entitled ''"JumpingTheShark"'' including references to [[Series/TheBradyBunch Cousin Oliver]], they find out that their father had a child several years after their mother died, whom he kept from the hunter's life to protect him. The brothers immediately argue about whether to train him or to spare him from their life. It turns out [[spoiler:he's already been killed in revenge against their father, and they've been dealing with a ghoul]].
** When Adam eventually makes another appearance in season five [[spoiler: as himself, after he's been [[BackFromTheDead brought]] back [[BackForTheDead from the dead]] as bait or a [[TakeAThirdOption possible alternative]] for Michael,]] he doesn't get along with either of the brothers that never knew about him. In Season six, when Dean's given the option to either [[spoiler:save Sam's soul from eternal torment in Lucifer's cage or rescue Adam's from the same place, Dean [[BigBrotherInstinct unsurprisingly]] doesn't even hesitate in choosing [[{{Protectorate}} Sam]]]].
** Simultaneously, within the archangels, [[ArchangelLucifer Lucifer]] and [[ArchangelMichael Michael]] are seeking the same Armageddon, each thinking they would win. Winchester brother intervention gets [[ArchangelGabriel Gabriel]] involved, introducing this dynamic between them to the viewers. Gabriel takes neither side, choosing ''humans'' instead, and is responsible for [[spoiler: telling Sam and Dean how to seal the both of them in Lucifer's Cage, preventing the conflict that would raze the world]].

* The show ''Series/{{Sisters}}'' originally had 4 sisters: Alex, Teddy, Georgie, and Frankie. In the 4th season, they discover they have a younger half-sister named Charley who was born from an affair their father had. Charley was a guest star in seasons 4 and 5 but when the actress who played Frankie left the show Charley (now with a different actress) became a regular character during the sixth season.
* Venus de Milo of the short-lived ''Series/NinjaTurtlesTheNextMutation'' series was a female turtle with the same MetaOrigin. But she got so much hate from the [[FanonDiscontinuity fans]] ''[[DisownedAdaptation and creators of the original series]]'', and the show got terrible ratings and was cancelled, so the whole thing is [[CanonDiscontinuity noncanonical]] now.
* ''Series/{{Gossip Girl}}'', where Chuck becomes Serena and Eric's adoptive brother when their parents are married. The siblings already knew Chuck, and because of his earlier attempt to rape Serena, neither of them trust him. While Eric is the first to come closer to Chuck, Serena still distrusts him and blames him for sending her porn magazines. [[spoiler: Though, as it turns out, they were sent by someone else. Their relationship gets even worse when Chuck's father dies]].

* In ''VideoGame/MortalKombatArmageddon'' Rain's Ending [[spoiler: it is revealed he is the third son of Argus - the other two being rivals Dagon and Taven]]
* ''VideoGame/TeamFortress2's'' Gray Mann not only twists the family dynamic like Seth, [[spoiler:he one-ups Cain, and murders ''both'' his brothers. ]]

* ''VideoGame/{{Blazblue}}'' have Ragna, Jin, and their sister Saya. Saya was kidnapped 10 years before the start of the story and is nowhere to be seen in the present, both Ragna and Jin assuming that she was long dead. [[spoiler: The ending of the second game came and revealed that she was very much alive and now the head of TheEmpire subjugating the world, additionally she's also possessed by a death god. So both brothers have to put aside their own animosity for each other and deal with their sister.]]

* In ''The Miser Brothers' Christmas'', a 2008 sequel to ''WesternAnimation/TheYearWithoutASantaClaus'', the squabbling title characters have to call a truce to confront their [[BigBrotherBully even nastier older brother]], the North Wind.
* {{Downplayed|Trope}} or {{averted|Trope}} in ''WesternAnimation/GravityFalls''--the relationship between the "original Mystery Twins," [[spoiler:[[LovableRogue Stan]] and [[ScienceHero Ford]]]], turns out to be a major part of the series, while their third sibling, Shermie, is only mentioned in passing. {{Justified|Trope}} because he was ([[WritersCannotDoMath apparently?]]) a baby when the other two left home; from a Doylist perspective, he only really exists to explain [[spoiler:where [[SeekerArchetype Dipper]] and [[FunPersonified Mabel]] came from]].
* On ''WesternAnimation/{{Daria}},'' the title character's mom, [[{{Workaholic}} Helen]], has an intense rivalry with her older sister, [[PrettyFreeloader Rita]], due to her perception that Rita has always been [[ParentalFavoritism their mom's favorite]] ([[spoiler:though Rita actually seems to think that Helen is]]). The youngest sister, [[CoolAunt Amy]], describes how she always felt like she was ignored and thus grew more independent...but as we see, [[NotSoAboveItAll she can be just as petty as the others]], and deftly plays them against each other. Helen and Rita also argue that a lot of her "isolation" from the family is actually a personal choice.

* ''VideoGame/XenobladeChronicles2'' has a subversion with [[ApocalypseMaiden Pyra/Mythra]] and [[BigBad Malos]], who while not fully siblings, are considered to be as such and have a CainAndAbel dynamic. Near the end of the game, it is revealed that [[spoiler: Pyra/Mythra and Malos were once two of the three cores of the Trinity Processor, which powered a supercomputer that awakened [[TheMonolith the Conduit]]. Pyra/Mythra was originally named Pneuma, and Malos was originally named Logos. However, the missing third core of the Trinity Processor, Ontos, is nowhere to be seen, as the Architect mentions that Ontos triggered a space-time transition event and [[LongLostSibling disappeared into another dimension]]. Though due to the Architect actually being Professor Klaus from [[VideoGame/{{Xenoblade}} the first game]], Pyra/Mythra having [[CombatClairvoyance Foresight]] as one of their abilities, and Malos wielding a Monado as his weapon of choice, players who have played through the first game can connect the dots easily to infer that Ontos [[CanonCharacterAllAlong is actually Alvis/the Monado]] from the first game. Sure enough, when ''Xenoblade Chronicles: Definitive Edition'' was released, Alvis' model was changed to have him bearing a red core crystal in the same shape as Pyra/Mythra and Malos' core crystals.]]

* ''VideoGame/XenobladeChronicles2'' has a subversion with [[ApocalypseMaiden Pyra/Mythra]] and [[BigBad Malos]], who while not fully siblings, are considered to be as such and have a CainAndAbel dynamic. Near the end of the game, it is revealed that [[spoiler: Pyra/Mythra and Malos were once two of the three cores of the Trinity Processor, which powered a supercomputer that awakened [[TheMonolith the Conduit]]. Pyra/Mythra was originally named Pneuma, and Malos was originally named Logos. However, the missing third core of the Trinity Processor, Ontos, is nowhere to be seen, as the Architect mentions that Ontos triggered a space-time transition event and [[LongLostSibling disappeared into another dimension]]. Though due to the Architect actually being Professor Klaus from [[VideoGame/{{Xenoblade}} the first game]], Pyra/Mythra having [[CombatClairvoyance Foresight]] as one of their abilities, and Malos wielding a Monado as his weapon of choice, players who have played through the first game can connect the dots easily to infer that Ontos [[CanonCharacterAllAlong is actually Alvis/the Monado]] from the first game. Sure enough, when ''Xenoblade Chronicles: Definitive Edition'' was released, Alvis' model was changed to have him bearing a red core crystal in the same shape as Pyra/Mythra and Malos' core crystals, albeit colored red.]]

* {{Downplayed|Trope}} or {{averted|Trope}} in ''WesternAnimation/GravityFalls''--the relationship between the "original Mystery Twins," [[spoiler:[[LovableRogue Stan]] and [[ScienceHero Ford]]]], turns out to be a major part of the series, while their third sibling, Shermie, is only mentioned in passing. {{Justified|Trope}} because he was a baby when the other two left home; from a Doylist perspective, he only really exists to explain [[spoiler:where [[SeekerArchetype Dipper]] and [[FunPersonified Mabel]] came from]].
* On ''WesternAnimation/{{Daria}},'' the title character's mom, [[{{Workaholic}} Helen]], has an intense rivalry with her older sister, [[PrettyFreeloader Rita]], due to her perception that Rita has always been [[ParentalFavoritism their mom's favorite]] ([[spoiler:though Rita actually seems to think that Helen is]]). The youngest sister, [[CoolAunt Amy]], describes how she always felt like she was ignored and thus grew more independent...but as we see, [[NotSoAboveItAll she can be just as petty as the others]], and deftly works to play them against each other. Helen and Rita also argue that a lot of her "isolation" from the family is actually a personal choice.

* ''VideoGame/XenobladeChronicles2'' has a subversion with [[ApocalypseMaiden Pyra/Mythra]] and [[BigBad Malos]], who while not fully siblings, are considered to be as such and have a CainAndAbel dynamic. Near the end of the game, it is revealed that [[spoiler: Pyra/Mythra and Malos were once two of the three cores of the Trinity Processor, which powered a supercomputer that awakened [[TheMonolith the Conduit]]. Pyra/Mythra was originally named Pneuma, and Malos was originally named Logos. However, the missing third core of the Trinity Processor, Ontos, is nowhere to be seen, as the Architect mentions that Ontos triggered a space-time transition event and [[LongLostSibling disappeared into another dimension]]. Though due the Architect actually being Professor Klaus from [[VideoGame/{{Xenoblade}} the first game]], Pyra/Mythra having [[CombatClairvoyance Foresight]] as one of their abilities, and Malos wielding a Monado as his weapon of choice, players who have played through the first game can connect the dots easily to infer that Ontos [[CanonCharacterAllAlong is actually Alvis/the Monado]] from the first game. Sure enough, when ''Xenoblade Chronicles: Definitive Edition'' was released, Alvis' model was changed to have him bearing a red core crystal in the same shape as Pyra/Mythra and Malos' core crystals, albeit colored red.]]

* Cain and Able being major players in the universe of the ''Wiki/SCPFoundation'', it's of course innevitable that their family shows up from time to time.
** [[http://www.scpwiki.com/scp-4840 SCP-4840]], a floating city that's supposedly the first ever city, built at the center of creation, was ruled justly and wisely by the first king of men, Adam el Asem. That was until Adam was inflicted by the first vice, envy, claiming a star as his crown and desiring to become ruler of all that is. Eventually, his sons saw his growing madness and acted. Able and Cain both tried to take Adam's crown, but failed. The youngest brother, though, stole it, and fled from the city. In the end, the narrator of this story [[spoiler:admits that he is Seth el Adam, and mentions a part of the story he left out: As a child, he had looked to the stars and asked his father for one of them. [[StartOfDarkness His father reached up and plucked one out]].]]

* The Noldor royal family in Creator/JRRTolkien's ''Literature/TheSilmarillion'': Fëanor (Cain), Fingolfin (Abel) and Finarfin (Seth). [[spoiler:The only surviving Noldor royal family members in the male line after the First Age were Finarfin, his daughter Galadriel, and Gil-Galad, an elven prince of undecided heritage. Arwen was Galadriel's granddaughter on her mother's side and Finarfin's great-granddaughter. There was also Maglor the Fëanorian, who turned into the Elven version of the Wandering Jew and [[PutOnABus never entered the story again]]. The House of Fingolfin survived in the female line, however, with Idril Celebrindal, daughter of Fingolfin's second son Turgon, marrying Tuor, a prince of Men, and giving birth to Eärendil, father of Elrond (whose significance should be obvious) and Elros (and thus ancestor to the royal family of Númenor and therefore of Arnor and Gondor.]] Tolkien never finally decided whether King Gil-Galad was a descendant of Fingolfin or Finarfin; in the published Silmarillion he's the former, but in Tolkien's latest drafts he's the latter.

* ''VideoGame/XenobladeChronicles2'' has a subversion with [[ApocalypseMaiden Pyra/Mythra]] and [[BigBad Malos]], who while not fully siblings, are considered to be as such and have a CainAndAbel dynamic. Near the end of the game, it is revealed that [[spoiler: Pyra/Mythra and Malos were once two of the three cores of the Trinity Processor, which powered a supercomputer that awakened [[TheMonolith the Conduit]]. Pyra/Mythra was originally named Pneuma, and Malos was originally named Logos. However, the missing third core of the Trinity Processor, Ontos, is nowhere to be seen, as the Architect mentions that Ontos triggered a space-time transition event and [[LongLostSibling disappeared into another dimension]]. Though due the Architect actually being Professor Klaus from [[VideoGame/{{Xenoblade}} the first game]], Pyra/Mythra having [[CombatClairvoyance Foresight]] as one of their abilities, and Malos wielding a Monado as his weapon of choice, players who have played through the first game can connect the dots easily to infer that Ontos [[CanonCharactorAllAlong is actually Alvis/the Monado]] from the first game. Sure enough, when ''Xenoblade Chronicles: Definitive Edition'' was released, Alvis' model was changed to have him bearing a red core crystal in the same shape as Pyra/Mythra and Malos' core crystals, albeit colored red.]]

* ''VideoGame/XenobladeChronicles2'' has a subversion with [[ApocalypseMaiden Pyra/Mythra]] and [[BigBad Malos]], who while not fully siblings, are considered to be as such and have . Near the end of the game, it is revealed that [[spoiler: Pyra/Mythra and Malos were once two of the three cores of the Trinity Processor, which powered a supercomputer that awakened [[TheMonolith the Conduit]]. Pyra/Mythra was originally named Pneuma, and Malos was originally named Logos. However, the missing third core of the Trinity Processor, Ontos, is nowhere to be seen, as the Architect mentions that Ontos triggered a space-time transition event and [[LongLostSibling disappeared into another dimension]]. However, due the Architect actually being Professor Klaus from [[VideoGame/{{Xenoblade}} the first game]], Pyra/Mythra having [[CombatClairvoyance Foresight]] as one of their abilities, and Malos wielding a Monado as his weapon of choice, players who have played through the first game can connect the dots easily to infer that Ontos [[CanonCharactorAllAlong is actually Alvis/the Monado]] from the first game. Sure enough, when ''Xenoblade Chronicles: Definitive Edition'' was released, Alvis' model was changed to have him bearing a red core crystal in the same shape as Pyra/Mythra and Malos' core crystals, albeit colored red.]]

* In ''Manga/OnePiece'', Luffy and Ace are revealed [[spoiler:to not be related, and have a third [[BloodBrothers Blood Brother]] named Sabo. In their youth, he was the physical midpoint of the three, and was TheSpock in their three man band. The story is told entirely through flashback, as Sabo is assumed dead and thus a PosthumousCharacter. His death, and Ace's subsequent death]] complicates every ''previous'' interaction between Luffy and Ace, their current situation, and [[GallowsHumor all those that would follow]]. Additionally, Ace's tattoo and Luffy and Ace's relationships with their TrueCompanions take new significance. In a cover, it is shown that [[spoiler:had Sabo lived, the three would be together, and to cement this "Good Future", Ace's tattoo loses its meaningful misspelling. It becomes further complicated when it's revealed that Sabo ''survived'' the incident that supposedly took his life, and has been in hiding for the last twelve years, apparently as a member of the Revolutionary Army. While undoubtedly a heartwarming revelation, it becomes HarsherInHindsight when one realizes that Ace died without ever knowing that his other brother was alive. And even moreso because Sabo had amnesia the whole the time, only remembering his life with Ace and Luffy upon learning of Ace's death...at which point he collapses in tears because he wasn't there to even attempt to save his brother.]]

* ''LightNovel/DateALive'' has Shido and Kotori (the former being adopted into the latter's family) suddenly encounter the former's younger biological sister Mana one day. What makes this complicated is that ''both'' Shido and Mana have amnesia and don't remember their pasts. Mana does have a locket containing a picture of her and Shido when they were a younger, which is how she recognises him when she coincidentally sees him in a video. The relationship is confirmed by DNA testing. The drama comes from the fact that Kotori is part of the organisation Ratatoskr, which seeks to control Spirits by making use of Shido's ability to seal their powers, while Mana is part of DEM, which tries to kill them, and she doesn't appreciate Kotori putting Shido at risk.

* In ''ComicBook/XMen'', a slip up by Mr. Sinister introduced an example. As explained on the TangledFamilyTree page, Scott Summers was introduced as an orphan, then met and established a relationship with his brother Alex. This lasted for quite some time, before Sinister hinted that there was at least one more brother out there. After a lot of plot changes and WordOfGod statements, the brother was set as Vulcan, a supervillain emperor. But of course, given that Sinister never gave a specific number (he merely said "brothers"), any or all of the other implied candidates could still ''also'' be Summers brothers.

* Damian Wayne, the fifth Robin, is this in spades. He's the youngest Robin ever, has a massively abrasive personality and is the only Robin to actually be a blood relative of Franchise/{{Batman}} (much to the discomfort of [[ComicBook/{{Nightwing}} Dick Grayson]] and Tim Drake, who are adopted sons of Batman).

* In ''Fanfic/TheBridge'' Godzilla Senior, the Godzilla active from 1984 until his death in 1996, has three "children" of sorts. Biollante and Xenilla [[note]] Spacegodzilla [[/note]] were spawned from his cells and see themselves as his eldest daughter and son respectively, with the adopted son of Senior, Godzilla Junior, as their younger brother. Junior was also the only one who got along with their "father". Biollante is neutral in the kaiju faction war, with Junior leading the Defender faction and Xenilla leading the Mutation fact against each other. In this case it's the "Seth" and "Cain" who quarrel.
* In ''Fanfic/PrincessTrixieSparkle'', it's revealed several chapters in that Celestia had hidden a sibling from her younger sibling Luna for her entire life (which, being immortal, is well over a ''millenium''). Said sibling, Astelle, is their FallenHero older sister and TheManBehindTheMan of the entire fic.

[[folder:Live Action TV]]

* ''Series/{{Charmed|1998}}'' revolved around three sisters, the [[TitleDrop Charmed Ones]]. One of the sisters died early in the show, so a half-sister was added down the line to complete the trio. The two elder sisters (Piper and Phoebe) tried to enlist the help of the new sister (Paige), who was reluctant to join them and almost joined the {{Dark Side}}. There were also episodes which focused on how Paige's personality affected the dynamics within the family (namely, an episode where Paige tries to rearrange everything in the house which causes tension between her and Piper). Paige was also far more emotional on decisions concerning the past of their grandparents.
* The show ''Series/{{Sisters}}'' originally had 4 sisters: Alex, Teddy, Georgie and Frankie. In the 4th season they discover they have a younger half-sister named Charley who was born from an affair their father had. Charley was a guest star in seasons 4 and 5 but when the actress who played Frankie left the show Charley (now with a different actress) became a regular character during the sixth season.

* ''Series/PeakyBlinders'': The introduction of Michael Gray--Polly's son, the boys' cousin--complicates the already-fragile relationships among the Shelbys. In particular, John and Polly square off on whether or not allowing [[spoiler:Michael to participate in the less-legal side of the business is a wise idea]].
* ''WebVideo/PrettyDudes'': The Gomez brothers Ellington and Marshall are joined by a ''middle'' brother Carver in the second season, who's devotion to their parents shows exactly why the other two brothers transplanted to LA in the first place.

* ''[[VideoGame/FireEmblemJugdral Fire Emblem: Genealogy of the Holy War]]'' ends up with a show down between [[spoiler: protagonist Seliph and his half brother and half sister Julius and Julia. Depending on the players actions Julia can either be an enemy or ally.]]

* ''VideoGame/{{Blazblue}}'' have Ragna, Jin and their sister Saya. Saya was kidnapped 10 years before the start of the story and is nowhere to be seen in the present, both Ragna and Jin assuming that she was long dead. [[spoiler: The the ending of the second game came and revealed that she was very much alive and now the head of TheEmpire subjugating the world, additionally she's also possessed by a death god. So both brothers have to put aside their own animosity for each other and deal with their sister.]]

Consider the trope namers. Many people know the story of CainAndAbel, the first children born in the Abrahamic religions. In the story, Cain kills Abel and was banished by God. What fewer people know is that AdamAndOrEve had several more kids, one of whom was named Seth. Seth would replace Abel as the "good" son, and while both he and Cain would have children[[note]]With whom was not specified. The Bible implies that they married women outside their family, but also states that Adam and Eve were the first humans. Interpretations vary; the most common stances taken today are to either ignore it or make incest jokes.[[/note]], Cain's lineage would be cursed, and would eventually all be doomed by the Great Flood. Noah and his family were descended from Seth, and as the only survivors of the Flood, this means that all humans are descended from Seth, taking both of their places as the future of humanity.