History Main / DoubleInLawMarriage

* A doujin drawn by the creator of ''Anime/TenchiMuyo'' shows that all of Tenchi's daughters end up marrying the sons of [[Anime/TenchiMuyoGXP Seina Yamada]]. Mind you, that's [[{{Polyamory}} seven girls between three boys]].

* ''Machinima/LiliumSims2'': Siblings Horitio and Isis are in {{Arranged Marriage}}s to another pair of siblings named Balatazar and Estella.

* In the original ''Literature/BrotherAndSister,'' the sister is married to the king at the end while the brother is still single (but fortunately [[BalefulPolymorph no longer a deer]]). Some versions give the king a sister for him to hook up with.

* In ''VideoGame/BubbleBobble'', twin brothers Bubblun and Bobblun are dating a pair of sisters named Betty/Peb and Patty/Pab.

* In Creator/MadameDAulnoy's "Princess Belle-Etoile" [[https://www.surlalunefairytales.com/book.php?id=36&tale=893 link]], a king and his brother marry two sisters. Unfortunately, there is a third sister, and the king and his brother don't have a third brother for her. She marries an admiral instead and becomes jealous. (Their children, three of the king's and one of the brother's, are then abandoned together, and despite being raised as brothers and sister, [[KissingCousins the king's daughter and the brother's son manage to fall in love and end up married]].)

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* A doujin drawn by the creator of ''Anime/TenchiMuyo'' shows that all seven of Tenchi's daughters end up marrying the three sons of [[Anime/TenchiMuyoGXP Seina Yamada]]. No, [[{{Polyamory}} the numbers don't match up]].

* ''Film/{{Twins}}'' ends with the eponymous twins marrying sisters and each having twins of their own.

[[folder:Fan Works]]
* In a [[Literature/TheLionKingSixNewAdventures series of books]] about ''Franchise/TheLionKing'', Simba and Nala have a son, Kopa, thus making him Kiara's brother. Guess who Kovu's sister, Vitani, is almost always paired up with.
* In ''Webcomic/HowIBecameYours'', Zuko gets together with Katara and Azula with Sokka.
* Many ''Franchise/{{Digimon}}'' fanfics and fans ship both Taito (Taichi and Yamato) and Takari (Takeru and Hikari)
* Many ''Series/{{Supernatural}}'' fans/fanfics that ship Sam and Gabriel also ship Dean and Castiel.
* The ''Fanfic/MegsFamilySeries'' features a BetaCouple in [[TheDitz Chris]] and [[DumbBlonde Jillian]], who are the siblings of OfficialCouple [[ButtMonkey Meg]] and [[OriginalCharacter Zack]] respectively (Half-siblings in Zack and Jillian's case).
* In ''Fanfic/AFrozenHeadache'', it's mentioned that Adgar and Arianna are brother and sister. Frederic and Idun are also siblings. Adgar and Idun are Elsa and Anna's parents, while Frederic and Arianna are Rapunzel's parents.
* Downplayed in ''Fanfic/SonOfTheSannin''. Naruto is dating Hinata while his cousin Karin ends up with Hinata's cousin Neji. The possibility of a natural attraction between the two clans is briefly suggested after the latter couple hooks up.
* The ''Franchise/TouhouProject'' fandom has the [[ShipMates double ship]] of [[OurVampiresAreDifferent Remilia]]/[[MindOverManners Satori]] and [[CreepyChild Flandre]]/[[DissonantSerenity Koishi]]. Note that until the 2019 manga ''Webcomic/TouhouChireikidenFoulDetectiveSatori'', [[ShipsThatPassInTheNight the Scarlets and the Komeijis had never actually interacted in canon]].
* ''Fanfic/LetMeHear'' ships Blake/Ruby and Weiss/Yang, with Ruby and Yang being biological sisters while Blake and Weiss are adopted sisters.
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* In ''Princess Belle-Etoile'', a king and his brother marry two sisters. Unfortunately, there is a third sister, and the king and his brother don't have a third brother for her. She marries an admiral instead and becomes jealous. (Their children, three of the king's and one of the brother's, are then abandoned together, and despite being raised as brothers and sister, [[KissingCousins the king's daughter and the brother's son manage to fall in love and end up married]].)

** ''{{Literature/Emma}}'': Brothers John and George Knightley marry sisters Isabella and Emma Woodhouse. As in ''Literature/SenseAndSensibility'', the heroine's marriage takes place at the end, while her sibling's marriage took place before the start of the book, so Emma and her Mr. Knightley have been LikeBrotherAndSister all her life.

-->--''Literature/ToKillAMockingbird''

** Explicitly done in Creator/MarkMillar's ''ComicBook/{{Trouble}}'', one of several reasons it was immediately declared CanonDiscontinuity.

* A doujin drawn by the creator of ''Anime/TenchiMuyo'' shows that all seven of Tenchi's daughters end up marrying the three sons of [[Anime/TenchiMuyoGXP Seina Yamada]]. No, the numbers don't match up.

** In most versions of Gareth's story, after he marries his DamselInDistress Lyonesse, her sister, the DamselErrant Lynette, falls in love with his brother Gaheris. Other versions have it the other way around.

* This occurs in ''ComicBook/JemAndTheHolograms'' with dating, not marriage. Kimber is dating Stormer. Stormer is the sister of Craig, who happens to be dating Kimber's foster sister Aja. Craig finds it amusing. They go on a double date, however Craig and Aja end up finding their siblings to be SickeningSweethearts.

* At the very beginning of ''Literature/ASongOfIceAndFire'', best friends King Robert and Ned Stark intend to do this. They had already betrothed Sansa and Joffrey, while Robb and Arya escorted Myrcella and Tommen to dinner, with the implication that they were trying to set them up. Later Catelyn Stark makes a contract with Walder Frey for Robb and Arya to marry two Frey siblings.

** Grand Princess Jinyan married Lin Xie while Jinyan's brother the Emperor and Lin Xie's sister Lin Yueyao; this causes Prince Qi and Lin Shu to be "double cousins". Because Consort Jing is Lin Xie's adopted sister, Prince Jing and Lin Shu are also considered "double cousins". This goes a long way in contributing to EveryoneIsRelated.

* In Creator/TheBrothersGrimm tale "Literature/SnowWhiteAndRoseRed," Snow White winds up with the prince who was [[spoiler: turned into a bear]] while Rose Red marries his brother. Since the girls grew up sharing everything, this is the closest they can come to sharing a husband, too. In the ''Anime/GreemsFairyTaleClassics'' adaptation, there's a bit of AdaptationExpansion: the brother appears earlier in the story, Rose Red [[RescueRomance helps him when he's wounded]] and there's quite a bit of ShipTease [[BetaCouple the two]].

* Natsuki Enomoto and Yuu Setoguchi are the first pair to become an OfficialCouple in the ''Music/ConfessionExecutiveCommitteeLoveSeries''. Meanwhile, Natsuki's little brother Kotaro is in love with Yuu's younger sister, Hina. [[spoiler:Although Hina has a crush on her upperclassman Koyuki at first, she eventually reciprocates Kotaro's love after Koyuki graduates]].

* Natsuki Enomoto and Yuu Setoguchi are the first pair to become an OfficialCouple in the ''Music/ConfessionExecutiveCommitteeLoveSeries''. Meanwhile, Natsuki's little brother Kotaro is in love with Yuu's younger sister, Hina. [[spoiler:Although Hina has a crush on Koyuki at first, she eventually reciprocates Kotaro's love after Koyuki graduates]].