History Main / FlirtyStepsiblings

Usually this is seen in the undertones of their behavior in a show, and it almost always happens when two people become step-siblings in adolescence. Sometimes though, this is unintentional on the part of the writers and attempts to make new step-siblings act like a long-time brother and sister [[RelationshipWritingFumble just come off as flirty]].

* Derek and Casey from ''Series/LifeWithDerek'' have a relationship full of BelligerentSexualTension. [[RelationshipWritingFumble This was unintentional]] on the writers' part, but very intentional on the actors'.

People who become step-siblings at a very young age and grow up together are more likely to consider each other truly siblings and thus off limits for dating. This may also cross the line in the supposed UsefulNotes/WestermarckEffect. This trope can be TruthInTelevision for many stepsiblings whose parents married during or after their puberty, though they rarely end up becoming an official couple due to social factors. However many people find this trope to be a form of IncestIsRelative.

[[quoteright:350:[[WesternAnimation/MartinMystery https://static.tvtropes.org/pmwiki/pub/images/rsz_135_full_6815.jpg]]]]
[-[[caption-width-right:350:Martin's feeling the brotherly warmth… in his pants.]]-]

Sort of a vanilla SubTrope of NotBloodSiblings. See LittleSisterHeroine for when the relationship is made more explicit and emphasized. This may be played as part of BlendedFamilyDrama.

Sort of a vanilla version of NotBloodSiblings. See LittleSisterHeroine for when the relationship is made more explicit and emphasized. This may be played as part of BlendedFamilyDrama.

People who become step-siblings at a very young age and grow up together are more likely to consider each other truly siblings and thus off limits for dating. This may also cross the line in the supposed UsefulNotes/WestermarckEffect, a theory that the instinctive biological aversion to mating with a sibling or childhood friend is highly dependent on actually being raised in close proximity to said sibling/childhood friend. This trope can be TruthInTelevision for many stepsiblings whose parents married during or after their puberty, though they rarely end up becoming an official couple due to social factors. However many actual people find this trope to be a form of IncestIsRelative.

* Even though the boy comes into the family through adoption rather than marriage, ''Literature/WutheringHeights'' fits the rest of the trope, and is what happens when this sort of relationship goes spectacularly badly wrong. (Although there is a school of thought that believes that Catherine and Heathcliff are actually half-siblings.)

::: Because AllAbusersAreMale and DoubleStandardRapeFemaleOnMale, it's assumed that Toby was the [[SexualExtortion perpetrator]]. He wasn't. AdaptationalConsent was in play.

* Yuuka and Atsuro Kiryuu in ''Manga/SensualPhrase'', though only in the manga. One of the side-stories [[ADayInTheLimelight focuses on this]], [[spoiler: and specially when Riri Kinoshita, an IdolSinger who has a crush on Atsuro, blackmails him into pretending to be her boyfriend under threats of spilling out the beans about their "incestuous" bond, which would ruin Atsuro's budding career. [[WhatAnIdiot And then she pisses him off via verbally abusing poor Yuuka]]...]]

* ''[[Film/DaddysHome Daddy's Home 2]]'' has a rare one-sided version of this. Dylan finally kisses the girl he has a crush on UnderTheMistletoe, [[spoiler: but it turns out to be stepsister Adrianna. Not only was Adrianna repulsed by the kiss, the entire family was shocked by this sudden turn of events.]]

* ''[[Film/DaddysHome Daddy's Home 2]]'' has a rare one-sided version of this. Dylan finally kisses the girl he has a crush on UnderTheMistleto, [[spoiler: but it turns out to be stepsister Adrianna. Not only was Adrianna repulsed by the kiss, the entire family was shocked by this sudden turn of events.]]

* Subverted in a case of ''Manga/DetectiveConan''. [[spoiler: A woman named Kimie had to give her toddler daughter Yukiko away to her husband's family due to [[BreakTheCutie the terrible circumstances she was going through after her husband was in jail]], and didn't know what had happened to her for many years. In the meantime, she got married to a man named Tsujimura, who had just gotten divorced and had a son named Takayoshi. Several years later, Takayoshi falls in love with a girl and brings her photo to his dad and stepmom... and the girl turns out to be Yukiko, who doesn't know anything about it. Tsujimura has a FreakOut and [[ParentalMarriageVeto forbids Takayoshi from dating Yukiko]], having recognized the girl's identity as his wife's estranged child... which he shouldn't have known, which then leads [[MurderTheHypotenuse to a]] [[UriahGambit horrifying reveal]].]]

* Morgana and Arthur in ''{{Series/Merlin|2008}}'' had a [[UnresolvedSexualTension very charged]] relationship in Season 1. "The Crystal Cave" [[spoiler:reveals that Arthur's father Uther is Morgana's biological father, having had an affair with Gorlois' wife Vivienne]].

* ''Series/TheSecretLifeOfTheAmericanTeenager''

* In ''VisualNovel/CinderellaPhenomenon'', one of Lucette's possible love interests is her stepbrother Rod. In his good ending, they're happily together but have to keep their relationship a secret from everyone else.

* The manga ''Yoru Made Matenai'' is built around this trope, with a wee bit of borderline [[LoliconAndShotacon shotacon]] fanservice.
* The main couple of ''Manga/MarmaladeBoy'', which starts with the two leads's parents switching partners and then all deciding to live together in one BigFancyHouse.

* Though not teen-aged, Erio and Caro from ''Anime/MagicalGirlLyricalNanohaStrikers'' were both technically adopted by Fate and, as shown in the companion manga, think of themselves as step-siblings. However, their relationship is so close as to be romantic that even other people in-universe [[ShipperOnDeck tried to push them toward each other]]. Pretty much becomes official as of ''[[Manga/MagicalRecordLyricalNanohaForce Force]]''.

* Another rated manga example, ''Ai Don't Koi'' from Yasuhira Nakanishi. The main character struggles between two choices: one is his [[ChildhoodFriendRomance Unlucky Childhood Friend]] whom he always thinks of as a little sister, another is the girl whom he had a gigantic crush on--until her mother married his [[TheCasanova father]].

* ''Manga/CherryJuice'': As the series progresses, step-siblings Minami and Otome often switch between sharing flirtatious romantic moments and BelligerentSexualTension.
* Subverted in a case of ''Manga/DetectiveConan''. [[spoiler: A woman named Kimie had to give her toddler daughter Yukiko away to her husband's family due to [[BreakTheCutie the terrible circumstances she was going through after her husband was in jail]], and didn't know what had happened to her for many years. In the meantime, she got married to a man named Tsujimura, who had just gotten divorced and had a son named Takayoshi. Several years later, Takayoshi falls in love with a girl and brings her photo to his dad and stepmom... and the girl turns out to be Yukiko, who doesn't know anything about it. Tsujimura has a FreakOut and [[ParentalMarriageVeto forbids Takayoshi from dating Yukiko]], having recognized the girl's identity as his wife's estranged child... which he shouldn't have known, which then leads [[MurderTheHypotenuse to a]] [[UriahGambit horrifying reveal]].]]
* [[spoiler: Kazuma and Tsubasa]] from ''Manga/HisAndHerCircumstances''.

* Yuzu and Mei from ''Manga/{{Citrus}}'' are two step-sisters who have to deal with their attraction to each other. Yuzu only liked males until she [[ClosetKey met Mei]].
* Defied in the manga version of ''Manga/BunnyDrop''. One of the reasons why Yukari and Daikichi decided against becoming an OfficialCouple was to avoid this trope. Daikichi's adopted daughter Rin and Yukari's son Kouki have romantic feelings for each other as teenagers. [[spoiler:Ultimately Rin and Kouki break up and Rin ends up with ''[[WifeHusbandry Daikichi]]''.]] The anime adaptation and film adaptation ignore the timeskip so they have [[MaybeEverAfter more implications]] that Daikichi and Yukari ended up together.
* ''Manga/DomesticGirlfriend'': Protagonist Natsuo has this two-fold, with several issues added into the mix. The elder sister, Hina, is his teacher, [[HotForTeacher whom he's been in love with for quite a while]], while he met the younger, Rui, in a casual outing with his friends and ended up losing his virginity to her. Then his father announces he's getting married again and, surprise, the woman's daughters are none other than Hina and Rui.
* In ''Manga/RandomWalk'', Yuka gets tutored by her "older brother" Towa, who is actually the son of her second mother from a previous marriage. At first, she sees him as nothing but an AloofBigBrother, until [[spoiler:he kisses her while drunk]], and realises that their lack of blood relation means that he's a guy she can potentially date. [[spoiler:]]

* ''Film/{{Clueless}}'' has Cher and Josh. It helps that their parents are no longer married.
* ''[[Film/TheBradyBunch A Very Brady Sequel]]'' approaches this trope when Greg and Marcia are reminded that they actually aren't at all related. In this case, it's also a reference to the fact that the actors playing Greg and Marcia (in the 70s TV series) were in an on-off relationship during their time on the series.

* The horror movie ''Film/{{Teeth}}''. The brother has spent most of his life with a crush on his step-sister and despises their parents for making them siblings.

* In ''Film/LoversOfTheArcticCircle'', Otto's divorced father marries Ana's widowed mother first when the two children are just ten years old. Then, as they are living together in the same house, a teen romance gradually develops between Ana and Otto into a full-blown sexual relationship which, however, they manage to keep completely secret from their parents/step-parents to the end.
* Nemo and Anna in ''Film/MrNobody'' started off as ChildhoodFriends who later become step-siblings and start developing a romantic relationship.

* In ''Literature/{{Twilight}}'' all the Cullens are adopted siblings and most of them are in a relationship with another Cullen, though the siblings thing is largely an act to explain why they move and cohabit together. In the movie, Jessica calls attention to how weird it is for them to act as siblings and be in a relationship.

* Harry and Elaine from ''Literature/TheDresdenFiles''. They were both adopted by their EvilMentor in their early adolescence, having no known genetic connection. Once puberty struck they took their relationship in the expected direction. For extra {{squick}} and horror, their EvilMentor (and foster father) secretly encouraged it to keep them isolated from their peers, paving the way to magically brainwashing them into being his enforcers.
* ''Literature/BigTrouble'' by Creator/DaveBarry subverts this. Matt and Jenny have a strong crush throughout most of the book. When their respective dad and mom hook up in the epilogue, however, they only go out on a few dates before realizing the whole thing's a little weird and deciding to just be friends.
* In the ''Literature/AmeliaPeabody'' books, Ramses and Nefret were raised as siblings from the ages of ten and twelve, respectively, but ended up falling in love and marrying, albeit with some complications.
* In the 18th-century French FairyTale novella ''Princess Lionette and Prince Coquerico'', the protagonists, Lionette and Coquerico, are stepsiblings. About midway through the story, it's revealed that Coquerico's mother, after handing over her son to the fairy Cornue, met Lionette's father and married him. (And, being a fairy tale, WickedStepmother comes into play, with Coquerico's mother devising the plan to get rid of Lionette.) This revelation does not prevent Lionette and Coquerico from falling madly in love with each other--the two of them get married at the end of the story.

* The whole point of ''LightNovel/BrothersConflict'', specially its visual novel counterpart.
* Discussed at length in ''Literature/WeCantRewind'':
-->'''Denise''': "What if all this other stuff had never happened? I mean, what if we'd never gone on this cruise, just spent a week in Vegas for our honeymoon, or something, and then we'd gone home and raised our kids normally? I mean, as normally as we could, of course. And what if they'd just naturally gotten sweet on each other when they got to be teenagers? Would you have let them go on dates with each other?"

* ''Series/TheSecretLifeOfTheAmericanTeenager''
* ''Series/{{Reaper}}'' has Sock getting a stepsister. She thinks of them LikeBrotherAndSister, but tends toward much IDidntMeanToTurnYouOn. ''He's'' trying to get in her pants. ([[{{squick}} He eventually succeeds]].)
* ''Los Serrano'' has the relationship in between Marcos and Eva. {{Lampshade|Hanging}}d in a dream sequence [[spoiler:[[ItWasHisSled despite the series itself being]] AllJustADream,]] where Marcos says their relationship isn't incest, "more like stepincest".
* From the Taiwanese drama ''Series/DevilBesideYou'', Qi Yue was being bullied by the son of the school's president, Jiang Meng, only to [[AllGirlsWantBadBoys fall in love with him]], after realizing that he was a JerkWithAHeartOfGold and actually a decent guy. Before either of them could understand their feelings, her widowed mother and his divorced father began dating, eventually becoming engaged. One of the main conflicts of the story is the main couple trying to work out their relationship amidst their parents' relationship as well.

* Inverted by Gina and Boyle in ''Series/BrooklynNineNine'', they had a sexual relationship, but when their parents got together and eventually married they had already broken up. This doesn't stop Boyle from bringing up their sexual history while talking about them as being stepsiblings.
* ''Series/{{Glee}}'': Now that their parents are married, Kurt and Finn. Of course, Kurt originally tried to get Burt and Carole together in an attempt to [[InvokedTrope invoke this]], as he had a crush on Finn for months beforehand ([[IncompatibleOrientation it didn't go very well]]). In every episode thereafter, however, well and truly averted; Kurt's interactions with Finn are nothing at all like his flirty, adoring interactions with his boyfriend Blaine, and the two stepbrothers seem to be uninterested in each other much of the time, and even vaguely dismissive.
* ''Series/TheFreshPrinceOfBelAir'': Inverted. Will's mother and Lisa's father take a liking to each other, and after their kids decide (at the altar) that they're not ready to be married, their parents step up, saying "[[WhyWasteAWedding Why waste a perfectly good ceremony?]]". [[WhatHappenedToTheMouse Interestingly enough, Lisa and her father both disappear immediately after the episode, rendering the point moot]].
* The German comedy series ''Türkisch für Anfänger'' ("Turkish for Beginners", 2006-2008) is about the family consisting of therapist Doris Schneider, her children Lena and Nils, her lover, later husband, police inspector Metin Öztürk, and his children Cem and Yagmur. One of the major plotlines of the series is the on-again-off-again romance between stepsiblings Lena and Cem. [[spoiler: At the end of the third season the two are a couple and Lena is pregnant.]]
* On ''Series/{{Degrassi}}'', Clare dates her mother's fiancé's son Jake. Later on, when they are thinking about having sex, Jake says they should just end the relationship because if they break up painfully it would get awkward, seeing as they are now related.

* ''Series/{{Shake It Up}}'' has the {{Belligerent Sexual Tension}} variety between [=CeCe=] and Logan [[spoiler:, although it is subverted since the parents didn't get married.]]
* In ''Series/GossipGirl'', Serena and Dan find themselves in this situation when their parents, Lily and Rufus, marry each other. [[spoiler: After they divorce, Dan and Serena get together, and end up marrying in the finale.]]

* Michael Fairgate and Paige Matheson had a relationship in Season Eight of ''Series/KnotsLanding''.
* ''Series/{{Veep}}'': The Season 7 premiere quickly reveals that the woman that Jonah married in-between seasons is his (former) stepsister from one of his mom's previous marriages. Neither of them sees anything wrong with this.

* [[EvilMentor Master Li]] in ''VideoGame/JadeEmpire'' runs a martial arts school, and his two prize students ([[TheChick Dawn Star]] and the [[PlayerCharacter Spirit Monk]]) both are his adopted children. [[spoiler: After certain revelations about Master Li, it becomes apparent that there is also a case of [[KissingCousins flirty stepcousins]] if the Spirit Monk enters into a relationship with Silk Fox.]]

* Neraxis from ''VideoGame/KingsRaid'' acts this way towards his step-sister Laias which infuriates Lilia, who is Laias' biological sister. [[note]]All three of them are descendants of ancient dragons.[[/note]] This gets lampshaded in a few official 4-komas.

* ''WebVideo/FriendshipIsWitchcraft'' features a (mostly) one-sided flirtation between Twilight Sparkle and Shining "Francis" Armor. In [[WesternAnimation/MyLittlePonyFriendshipIsMagic canon]], they're biological siblings, but in this universe, [[RunningGag "They're not biologically related, so technically it's okay."]]

* ''WesternAnimation/TeenageMutantNinjaTurtles2012'' has Leonardo and Karai. They're flirty before they realize that Karai is actually the long-lost daughter of Splinter (aka Hamato Yoshi), who raised Leonardo from childhood. After the reveal, they actually grow closer, and though the attraction isn't explicitly referred to as much, they tend to treat each other a bit too intimately for step-siblings.
* ''WesternAnimation/MartinMystery'': It takes the subtext to the nth degree. They were really pushing it to the limit. That's what happens when you take characters who were lovers in the original comic and [[SiblingSwitchSquick turn them]] [[DubText into]] NotBloodSiblings.

* ''Los Serrano'' has the relationship in between Marcos and Eva. {{Lampshade|Hanging}}d in a dream sequence ([[spoiler: [[ItWasHisSled despite the series itself being]] AllJustADream, but anyway]]) where Marcos says their relationship isn't incest, "more like stepincest".

* Subverted in a case of ''Manga/DetectiveConan''. [[spoiler: A woman named Kimie had to give her toddler daughter Yukiko away to her husband's family due to [[BreakTheCutie the terrible circumstances she was going through after her husband was in jail]], and didn't know what had happened to her for many years. In the meantime, she got married to a man named Tsujimura, who had just gotten divorced and had a son named Takayoshi. Several years later, Takayoshi falls in love with a girl and brings her photo to his dad and stepmom... and the girl turns out to be Yukiko, who doesn't know anything about it. Tsujimura has a FreakOut and [[ParentalMarriageVeto forbids Takayoshi from dating Yukiko]], having recognized the girl's identity as his wife's estranged child... which then leads [[MurderTheHypotenuse to a]] [[UriahGambit horrifying reveal]].]]

* Subverted in the manga version of ''Manga/BunnyDrop''. One of the reasons why Yukari and Daikichi decided against becoming an OfficialCouple was to avoid this trope. Daikichi's adopted daughter Rin and Yukari's son Kouki have romantic feelings for each other as teenagers. [[spoiler:Ultimately Rin and Kouki break up and Rin ends up with ''[[WifeHusbandry Daikichi]]''.]] The anime adaptation and film adaptation ignore the timeskip so they have [[MaybeEverAfter more implications]] that Daikichi and Yukari ended up together.

* ''WesternAnimation/MartinMystery'': It takes the subtext to the nth degree. [[GettingCrapPastTheRadar They were really pushing it to the limit.]] That's what happens when you take characters who were lovers in the original comic and [[SiblingSwitchSquick turn them]] [[DubText into]] NotBloodSiblings.

* ''Series/DrakeAndJosh'' fans aren't imagining things when they say the step-brothers act more like a couple. Their constant bickering LikeAnOldMarriedCouple doesn't even scratch the surface. The Nickelodeon KidCom hit the ground running with this vibe between them and never stopped, from the numerous times they use flirty (or, in Drake's case, seductive) tones with each other, a bit where Drake apologizes to Josh by acting like he's proposing to him, that time they both started hanging out with the other's doppelganger in a mutual OperationJealousy, the time Josh dumped Drake for good and insisted that from now on, "all we'll be is roommates," to all the times they've kissed. Including once ''on the lips''.

* ''Series/DrakeAndJosh'' fans aren't imagining things when they say the step-brothers act more like a couple. Their constant bickering LikeAnOldMarriedCouple doesn't even scratch the surface. The Nickelodeon KidCom hit the ground running with this vibe between them and never stopped, from the numerous times they use flirty (or, in Drake's case, seductive) tones with each other, a bit where Drake apologizes to Josh by acting like he's proposing to him, that time they both started hanging out with the other's doppelganger in a mutual OperationJealousy, the time Josh dumped Drake for good and insisted that from now on, "all we'll be is roommates," to all the times they've kissed. Including once ''on the lips''.

* [[spoiler: Kazuma and Tsubasa]] from ''Manga/KareKano''.

* ''Series/TheFreshPrinceOfBelAir'': Inverted. Will's mother and Lisa's father take a liking to each other, and after their kids decide (at the altar) that they're not ready to be married, their parents step up, saying "[[WhyWasteAWedding Why waste a perfectly good ceremony?]]"

* In the [[WebAnimation/HomestarRunner Sbemail]] "What I Want" Strong Bad says he wants a hot stepsister.

* ''VideoGame/ValkyriaChronicles'': The main character makes his "Adopted" sister's non-blood relation clear to a very suspect degree.