History Main / AFamilyAffair

* ''WesternAnimation/FamilyGuy'': Attempted but ultimately averted in ''"[[Recap/FamilyGuyS5E13BillAndPetersBogusJourney Bill and Peter's Bogus Journey]]"''. Trying to fix their relationship after cheating on his with UsefulNotes/BillClinton, Lois allows Peter to have an affair of his own so that they're even. He decides to sleep with her mother and she's all for it, but he ultimately can't bring himself to do so. Instead he confronts Bill for being a homewrecker...only to be seduced and bedded by him as well.

* ''Series /PersonOfInterest'': In [[Recap/PersonOfInterestS03E19 Most Likely To...]] John Reese poses as Frank Mercer to infiltrate a school reunion, and gets slapped by random women. Harold Finches finds out Mercer had a fling with a girl and seduced her mother, who is still sore about it after twenty years.

* ''Series/MoonLovers'' has an especially icky version. (Let's just say it's a ''[[BrotherSisterIncest family]]'' affair in a more-literal-than-usual way.) Yeon-hwa implicitly has an affair with her half-brother Wang Yo, who wants to marry her, but she would much rather marry his full brother Wang So. After Yo's death she eventually makes So marry her.
** On the slightly less icky side, Ha-jin/Hae-su falls in love with Wang Wook, who's married to her distant cousin Myung-hee. After Myung-hee's death Wook offers to marry Ha-jin, but instead she falls in love with his half-brother, the aforementioned Wang So. And in the end she marries yet another half-brother, Wang Jeong.
* On ''Series/MyNameIsEarl'', Joy very nearly leaves Earl ''on their first wedding anniversary'' for his ManChild cousin that she had hooked up with in the past before meeting Earl. [[spoiler: Earl protects her from a killer bee by stabbing it with a skewer from a corn dog, proving to her that he ''does'' care about her, and she goes back to him...though she eventually has an affair with Darnell.]]
* ''Series/ScarletHeart'': Zhang Xiao/Ruo Xi and Yin Si are siblings-in-law but are romantically involved for a while. After breaking up with him Zhang Xiao falls in love with his brother Yin Zhen, and after ''that'' relationship ends she marries Yin Ti, yet another brother.

* The Creator/{{HBO}} movie ''Above Suspicion'', starring Creator/ChristopherReeve and Creator/KimCattrall as husband and wife Dempsey and Gail, in which Gail is having an affair with Dempsey's brother Nick. Dempsey ends up killing them both and successfully spinning it as self-defense.

* ''Literature/TheNight'sDawnTrilogy'': Dashing space trader/smuggler Joshua Calvert visits a [[SpaceAmish world with the social structures of eighteenth-century England]] and Louise, a young woman there, develops a crush on him. Her mother, fearing the potential consequences of Louise having pre-marital sex, seduces Calvert in the hope of keeping his penis occupied (it doesn't hurt that her husband is adulterous and that she herself has a crush on Calvert). Calvert seduces Louise anyway, and ultimately ends up marrying her at the end of the series.

* In ''VideoGame/TheWalkingDeadSeasonThree'', Javier has the option of reciprocating the feelings of his sister-in-law, Kate, whose husband and Javier's brother, David, is presumed dead. Even before the outbreak, Kate and David's relationship was already strained due to him being unpleasant. He's even confided to Javi that he's realized he hates being a family man to the point that he wants to leave and entrust his wife and family to Javi. [[spoiler:When it turns out David is alive, it complicates things. He'll be upset when he thinks Javi and Kate are together and accuses Javi of stealing his family (regardless of whether or not Javi has been accepting Kate's advances, Kate deliberately pushes David's BerserkButton at one point by suddenly kissing Javi). In the ending, Kate won't feel bad if David was killed and urges Javi to do the same, though if Gabe was also killed, she'll ask for some space, but will otherwise want to pursue their relationship.]]

* The accusation of this is likely what led to [[UsefulNotes/TheRomanEmpire Emperor Constantine]] [[OffingTheOffspring condemn and execute his son, Crispus]]. He was accused of having an affair with the empress and his step-mother Fausta, though it's still debated by historians whether she accused him of the crime or the two actually had an affair.

* ''Franchise/{{Batman}}'': Post-Crisis, Commissioner Gordon became [[ComicBook/{{Batgirl}} Barbara Gordon's]] uncle and adoptive father rather than her biological father as he had been before, but Barbara later discovered that he may have been sleeping with his brother's wife around the time she was conceived, [[LukeIMightBeYourFather implying she may have been his biological daughter]].
* ''Franchise/SpiderMan'': ComicBook/NormanOsborn had an affair with his son's fiancée Lily Hollister. [[AbusiveParents This isn't even the worst thing he's done to Harry]].
* ''Franchise/WonderWoman'':

* In ''VideoGame/TheWalkingDead Season 3'', Javier has the option of reciprocating the feelings of his sister-in-law, Kate, whose husband and Javier's brother, David, is presumed dead. Even before the outbreak, Kate and David's relationship was already strained due to him being unpleasant. He's even confided to Javi that he's realized he hates being a family man to the point that he wants to leave and entrust his wife and family to Javi. [[spoiler:When it turns out David is alive, it complicates things. He'll be upset when he thinks Javi and Kate are together and accuses Javi of stealing his family (regardless of whether or not Javi has been accepting Kate's advances, Kate deliberately pushes David's BerserkButton at one point by suddenly kissing Javi). In the ending, Kate won't feel bad if David was killed and urges Javi to do the same, though if Gabe was also killed, she'll ask for some space, but will otherwise want to pursue their relationship.]]

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Adultery is considered to be a betrayal on the cheater's behalf, and a major source of drama because of it. And as family is supposed to look out for one another, when the person they cheat with is a relative of the cheated partner it's [[TreacheryIsASpecialKindOfEvil all the more of a betrayal, and thus all the more dramatic]]. Usually it's the wife sleeping with her brother-in-law, or brother sleeping with his sister-in-law, though sometimes it's the parent or child. Doing so means they're almost universally considered a {{Jerkass}} for betraying their own loved one's trust, and the affair is usually on the bad end of GoodAdulteryBadAdultery. Of course, it's possible for it to be sympathetic if the relative is far nicer than the spouse being cheated on, or the cheaters wanted to be partners in the first place but had to settle for the other relative. Maybe it's just a sign of a DysfunctionalFamily.

** ''ComicBook/WonderWoman1987'': While Aphrodite's parentage is left vague her she cheats on her husband Hephaestus with his brother Ares, and has several children with Ares.

* Downplayed in ''Fanfic/{{Chemistry}}''. Cadance is attracted to her husband's younger sister Twilight, but it's likely unrequited.

--> ''A man goes to meet his fiance's family, and while they all seem friendly enough, he notices that her younger sister seems quite smitten with him, contriving to jiggle her cleavage whenever he looks in her direction, dropping things and bending over to pick them up while next to him, playing footsies under the table at dinner, etc. Finally he ends up alone in a room, when the sister enters half-naked and orders him in no uncertain terms to ravish her then and there, adding that her sister will never know anything about it. Without a word, the man gets up, leaves the room, goes down the stairs, exits the house, and already has his car keys out when the rest of the family pops out of hiding, [[OverprotectiveDad the father putting down his baseball bat to congratulate him on passing the faithfulness test]].

* ''Manga/KanonByChihoSaito'': [[spoiler:Gen Mikami sleeps with his fiancee Maria's mother. Maria [[{{Yandere}} doesn't take it well]].]]

Compare SiblingTriangle, where both siblings are knowingly competing for the third one and TwoTimingTheBestie, where a character's partner cheats on them with a friend of theirs.

Compare SiblingTriangle, where both siblings are knowingly competing for the third one.

* ''Manga/{{Mars}}'': Two significant ones:

* In ''Film/SoulFood'', Nick cheats on his wife Teri with her cousin Faith.

* As seen above in the page quote, in ''Fanfic/TheVictorsProject'', Finnick reveals that a Capitol citizen cheated on her husband with several of his family members.

->''"Potoma Lewis very much enjoys the affections of her husband, and her husband’s brother, and her father-in-law, and several of his cousins, and has even dabbled around with her dear husband’s elderly aunt on occasion."''