"Jaime and I are more than brother and sister. We shared a womb, came in to this world together. We belong together."Popular culture often expects twins to share everything, including, it seems, their beds. It's a particularly common trope in Slash Fic and Rule 34, though it does occur in mainstream fiction often enough to be a discernible trope. It's especially common as a way of making Creepy Twins just that much more disturbing, often as a form of Villainous Incest. For Yuri Fans and Yaoi Fans who became fans at least partly because they see a forbidden appeal to such relationships, twincest supercharges that part of the appeal. Though twincest is not necessarily homosexual—heterosexual Half-Identical Twins tend to have the highest rate of twincest. A common twist in Twincest—and in Brother–Sister Incest in general—is Surprise Incest: for a couple to fall in love, only to find out later that they're related. (See genetic sexual attraction.) The fact that Separated at Birth is already a common twin trope reinforces this. How far their relationship goes before they discover this generally depends on whether the plotline is supposed to be humorous or tragic. In other variations, the twins know perfectly well that they're related, and might like each other all the more for it—if you believe in One True Love, soulmates being born together does make a certain kind of sense. Mindlink Mates and Twin Telepathy definitely have parallels. Ultimately, although this is fairly exploitational, such a rationale is the simplest and most common in modern works where twins enter into romantic or sexual relations deliberately and voluntarily. Commonly, the twins in question believe they're soulmates, but everyone else has a "No. Just... No" Reaction. An old Japanese myth says that if two star-crossed lovers commit dual suicide, they get reincarnated as twins. This may be one of the factors in the frequency of Twincest stories in anime. In this case, Red String of Fate and, as a whole, esoteric-religious motives such Reincarnation Romance can be used as a justification for obviously taboo relations. In a broader religious or mythological context, this trope can be regarded as Older Than Feudalism, given the many similar myths in different nations where twincest is directly mentioned or implied in the context of couples from Half Identical Twin gods who are portrayed as appointed to become husband and wife, or as the first people in general. Twincest is not the same as Twin Threesome Fantasy. Twincest is all about twins screwing each other; in a Twin Threesome Fantasy, the focus is either on the third, non-twin party, or on each other but for the benefit of the third party. Even with true twincest, sometimes the appeal to viewers comes from the idea of inserting themselves and turning it into the fantasy. Twin Threesome Fantasy is to Twincest as Girl-on-Girl Is Hot is to Queer Romance. They can overlap if the twins are interested in both each other and the third party, but that's rarer. If the twins have a child together, that may be known as twinbreeding. It goes without saying that most Real Life twins are as completely repulsed by the idea as any other incest trope. A subtrope of Brother–Sister Incest. If it's just implied, then it overlaps with Incest Subtext. It's also important not to make mistakes with other Brother–Sister Incest couples, since, due to the popularity of this trope and the idea of a spiritual bond of twins, many "ordinary" couples between brother and sister can imitate many twincest cliché elements. And of course, sometimes even Twincest isn't quite incestuous enough for the writers, and that's when you get Screw Yourself.
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Anime & Manga
- Angel Sanctuary: Let's not get started on Rociel/Roshiel's "ambiguous" attitude towards his twin sister Alexiel. But then again, Rociel isn't a paragon of sanity, and brother-sister incest is one of the main themes of the manga.
- Ayashi no Ceres plays this trope quite creepily and mixes it with Rape as Drama. The actual twins, Aya and Aki, care for each other deeply but don't have twincestuous feelings for each other; they are, however, possessed by their ancestors, Shisou and Ceres, who were husband and wife.
- Black Lagoon's Hansel and Gretel. Given their history, this is possibly the least disturbing thing about them.
- The Hayasaka twins from Busou Renkin, while probably not involved in actual twincest, do act a lot like a married couple, and as kids, used to recite the traditional wedding vows to each other as a game. This was done by their kidnapper, a woman whom have had an affair with their biological father that was later broken off. After being spending nearly three years with the woman, they suffered a Parental Abandonment with the "marriage game" being their only happy memory giving them a "us vs the world" codependent mentality similar to the Hitachiin twins. Meeting Kazuki Muto helped them become individuals but are still close.
- Candy Boy is entirely about yuri twincest, in that Yukino does like to tease her sister Kanade quite a bit. There's nothing explicit going on, since Kanade decides to keep a cool outer appearance, although she is obviously enamored with her sister. Something explicit is going on by the end. They kiss in the last non-DVD episode. The manga also revolves around their romantic, and sometimes sexual, feelings for each other.
- In Castle Town Dandelion, one of Misaki's clones (Shaura) embodying her repressed lust shows strong affection towards her twin brother Haruka, while teasing Misaki that this is what she truly wants; though she denies this, Shaura also states that the reason for Misaki partaking in her country's election are all to gain Haruka's attention, all away from her other sisters.
- Chobits has some extremely un-sibling-like touching between Chi and the "Dark Chi" that appears in her mind. This proves to be her sister, Freya, whose mind was downloaded into Chi.
- A Cruel God Reigns: Eric and Valentine. Eric became dangerously dependent on his twin sister after being molested by their piano teacher as a child. Unable to separate comfort from romance, the two had sex and Valentine had a baby at 13 years old.
- This makes up all the drama in one case in Detective Conan. Raita Banba, a high school friend of Kogoro's, had a fiancée named Hatsune Kamon. On the eve of their wedding, Hatsune was killed when the car exploded, and Raita was the main suspect due to his Crazy Jealous Guy tendencies. It was later revealed that they were Half-Identical Twins, who were separated when they were babies after a house fire, and the two didn't know that they committed twincest until Hatsune received a call that the DNA results confirms that. Already very stressed from the thought of Raita's and her origins and the fact that she was an Ill Girl, poor Hatsune soon fell into the Despair Event Horizon and as a result, she committed suicide.
- In fact her Ill Girl status is what made her start her fall. Turns out that Hatsune suffered from Turner syndrome which is what happens when one of the sex genes, either the second X or the Y, is missing or structurally altered. Hatsune is in fact Raita's genetic twin and would have probably been born male.
- Digimon Frontier: While the newly-reunited twins Kouji and Kouichi are distinctly not an example, it does get used as a joke in episode 41. Kouji saving his brother from Crusadermon ends in an awkwardly dramatic moment◊ (possibly enhanced by in-universe Shipping Goggles), which leads the beauty-obsessed Crusadermon to declare, "Ah, brotherly love is grand!"The other observing Legendary Warriors are notably disturbed.◊
- D.N.Angel features some Les Yay between twins Risa and Riku, though mostly in color illustrations. There's a rather eyebrow-raisingly sensual pic of them laying side-by-side on a bed. One shall also note that they get a pinky thread of love together.
- .hack//Legend of the Twilight hints strongly at incest, or at least lust, between twins Shugo and Rena. This is basically a Flanderization of subtler jokes in the manga, where it was the sister's completely different-looking and skimpily-dressed computer avatar that set off the whole thing. The anime altered the storyline near the end where their relationship is implied to be much stronger.
- Durarara!!'s Mairu and Kururi Orihara have somewhat incestuous feelings towards one another, largely owing to the fact that they're not quite right in the head… (they don't actually consider themselves separate individuals, for starters).
- Though barely present in the main story of Earthian, other than a mention now and again by his assistant and close friend Raphael, Lord Michael and his twin sister Lucifel are featured prominently in an extra story, written years following the original publishing, that was included in the reprint. In the story, not only is Lucifel shown to be extra touchy-feely with Michael (not to mention possessive of him, to the point where Raphael considers her his romantic rival), it is strongly implied that not only do they eventually have sex, but Lucifel has a child by him, that child being Kagetsuya, one of the two main characters of the main story. This becomes somewhat less of a shock when you consider the mangaka is Yun Kouga (see Loveless).
- In Full Metal Panic!: The Second Raid, the assassins Xia Yu Fan and Xia Yu Lan are twin sisters who take showers together. And hold each other at every available opportunity. Also Yu Lan sees Yu Fan descending naked from the sky toward her when she dies.
- Gundam 00 plays with this too. Whether Ribbons Almark and his "sister" Hilling Care qualify as twins is debatable, both of them being DNA-engineered children with the same sequence, but Healing seems to show a bit more adoration than is platonic towards Ribbons.
- The relationship between Carossa and Melissa in GUN×SWORD has elements of this, though they are never so pronounced as when the two first appear and Carossa licks away Melissa's tears. Van, watching, cannot help but be a little disturbed. They are basically kids. What was there was creepy, particularly Carossa managing to imply "Abusive Relationship" while being all of twelve years old.
- The Kannazuki no Miko manga ends with Chikane and Himeko reincarnated as twin sisters. This may be a variation on the Japanese myth mentioned above.
- Masako and Kanba from Mawaru-Penguindrum, sort of: Masako openly chases after Kanba, but though he cares for her, he doesn't reciprocate.
- Subverted in Mobile Suit Gundam SEED: Kira and his Separated at Birth twin sister Cagalli meet in the first episode, neither knowing they're related. When they reunite further in the series, Cagalli comforts the emotionally ragged Kira in a purely platonic way. This is ironically taken as a threat by Flay, Kira's screwed-up girlfriend (it's not a healthy relationship), despite the fact there's no romantic attraction to it. Further toyed with when Cagalli displays a Luminescent Blush at overhearing Flay admit to her ex-fiance Sai that she and Kira have slept together, and when Kira's adoptive parents Caridad and Haruma (who are aware of Cagalli's identity, as the mother rescued both twins as babies from the place where their biological parents died) show a bit of alarm when Cagalli hugs Kira goodbye. They're informed of their true relationship before things have a chance to go any further.
- In Monster, there is a one-sided example with Johan Liebert and his twin, Anna. Unfortunately, Johan is also really scary and effectively scares Anna half to death whenever she thinks about him. Although, considering how he treats other people, this may be the only way he's even capable of displaying affection whatsoever. It doesn't seem to be brotherly love, though, when he talks about her as his "other half". It comes off as a really creepy infatuation, usually.
- Myself ; Yourself has twins Shuri and Shusuke with a particularly strong relationship in the face of Parental Abandonment, with a later rumor even claiming a more illicit relationship. Under threat of separation, they run away together near the end. The Distant Finale goes on, giving them a strange Maybe Ever After the end, where they attend a concert of main characters, holding hands. The original game at the same time plays with it, giving the both twins the other Love Interest, but at the same time having a scene with Shusuke in the route of his sister, where he confesses to one-sided feelings towards her. Nevertheless, despite all the ambiguity, it's still Fanon among fans.
- The first episode of Osomatsu-san parodies this. The characters try to re-imagine Osomatsu-kun for a modern day audience as an idol, harem show with a Cast Full of Pretty Boys. This includes Incest Subtext between the brothers (mind you they're sextuplets).
- Ouran High School Host Club: This is the main "schtick" of Genre Savvy Hikaru and Kaoru: making the club's female clients swoon and sigh over "the forbidden love between brothers!!!" Whether it's a put-on or not is hard to tell, given their trickster personalities. They seem to be very affectionate toward each other when the fangirls aren't watching—but this, too, could also be a game they play. Nevertheless, on one occasion where Tamaki calls them early on a weekend, we see them waking up in bed… the same bed… cuddling each other. Naked. It's also deconstructed, as the twins are revealed to be dangerously codependent. In the manga, this eventually sparks a feud between them, and they eventually learn how to be individuals.
- Teased with The Demon Sisters in Panty & Stocking with Garterbelt, who are a little too nice to one another. They briefly engage in twincest in the second to last episode.
- Please Twins! features a boy who is not sure which of the two girls in the story is his long-lost twin sister. They both fall for him, making one a case of twincest and the other not. Now, if only they knew which… if only the manga and anime were the same on that point…
- In Revolutionary Girl Utena, Half-Identical Twins Miki and Kozue have a bizarre relationship which may involve twincest, particularly in the movie.
- Rozen Maiden: Suiseiseki and Souseiseki—a.k.a. the Boatlight Twins—get this kind of treatment a lot through fan shipping. To be fair, they are an official pairing in the series itself, so it works out pretty well overall anyway.
- Saiyuki: Hakkai's girlfriend Kanan was actually his Separated at Birth twin sister. It's not known when they found out, but it was Hakkai's motive for what he did after she was given up to the demons by the villagers, gang raped, forcibly impregnated, and then Driven to Suicide. And apparently even after they found out, they didn't actually break up or anything.
- In selector infected WIXOSS Yuzuki is in love with her twin brother and wishes to become his girlfriend. She ends up actually getting her wish granted, but at the cost of her LRIG, Hanayo, swapping places with her. Still, she doesn't hold much of a grudge against Hanayo, as she did fulfill Yuzuki's wish, and had no malicious intent when she took over her body.
- Tsubasa -RESERVoir CHRoNiCLE-: The Acid Tokyo arc's Kamui and Subaru (also known as the "Vampire Twins") actually manage even more Ho Yay than their counterparts in X1999 (where they are not related in any way). Vampirism (and new twincest possibilities) may have something to do with it.
- Sei and Kai in Uta Kata, whose relationship is ambiguously romantic until Kai gives Sei a Last Kiss and says he loves him. Of course, they're not actually twins, or even related.
- Zero and his long-lost twin Ichiru in Vampire Knight. The 'cest is entirely irrelevant to the plot. It just needed that extra element.
- In a similar CLAMP example, see Hinoto and her hallucinatory Evil Twin in X1999.
- Yosuga no Sora is practically Trope Codifier of this trope for H-Game and especially anime, gradually and in detail depicting the development of romantic feelings between Half-Identical Twins Sora and Haruka Kasugano and their different approaches in the awareness and acceptance of their feelings for each other.
- Naohiro from Yandere Heaven has feelings for his twin sister. Since they're the only family they have (with the exception of their stepfather), Nahiro has done his best to take care of her. His ending hints that he may have an Entitled to Have You behavior because they're twins and he believes that they should love each other and die together no matter what.
- A special twist for the third volume of Yandere No Onna No Ko is Alice harboring a one-sided crush on her twin sister. Everything she had done was to make sure that no one took her loved one away from her. Unfortunately, this led to Elise killing herself because her sister refused to let her interact with anyone other else. It's suggested that Alice also kills herself to join her sister in death.
- Afterlife with Archie implies Cheryl and Jason have incestuous affections towards each other. It's suggested not all of it is entirely consensual on Cheryl's part.
- In Grendel, Orion Assante has a three-way incestuous relationship with his twin sisters, until they get murdered to help motivate him.
- It was heavily implied in a few issues of Infinity, Inc. that Obsidian has a crush on his long-lost twin sister Jade (this despite Obsidian being gay). She was blissfully oblivious.
- In Lazarus Jonah and Johannah Carlyle are sleeping together and plotting to usurp the family holdings from their father. However when one of Jonah's badly underthought plans goes wrong, Johannah plays the Wounded Gazelle Gambit and pretends that Jonah betrayed her as well.
- Marvel Comics: The Fenris twins (Andrea and Andreas Von Strucker) play with this idea—and likely, each other!—fairly frequently. And then it got worse gets worse. Andrea has since died, and since their energy blast powers relied on them touching to function, her brother had her skin made into leather and wrapped his sword hilt with it. On top of that, he is nothing short of fanatically obsessed with finding a way to resurrect her. The whole thing is portrayed just as creepily as it sounds, with even other characters around him being squicked by it. Their Ultimate versions were pretty much the same, save for the bit in spoilers. However, when Andrea is later cloned, her brother tries to deny that their relationship was ever incestuous. He allows her to sleep in a separate bed, and claims that while he knows his teammates think that he's a freak, he has no actual desire to have sex with his sister. Then due to some very complicated developments, Clone Andrea and Andreas both died. But then they were back as usual running a nightclub for super villains, and it was unclear again. After years in limbo, it was finally made canon in JSA.
- Aleksandr and Aleksandra Ramanov in Nikolai Dante are like this, even taking time out of killing the Raven Corps to make out.
- Top 10's Spin-Off miniseries Smax has Smax and his sister Rexa admitting to this, although in the world they came from it wasn't the taboo issue it was in his adopted world. When she moves to Jeff's world they pose as unrelated lovers—Robyn alone knows the truth but doesn't have a problem with it.
- In the Ultimate Marvel universe, there were hints about Quicksilver and Scarlet Witch going down this road from the beginning, until it was confirmed outright in The Ultimates 3, immediately before her death.
- They are clones rather than twins, but the girls in the XXXenophile story "Family Reunion" probably count.
Fandom & Fan Works
- Saint Seiya twins Gemini Saga and Gemini Kanon make one of the most popular and accepted couples among slash and yaoi fans in this series both in the manga and anime because of their dramatic and conflictive relationship as twin brothers who love and hate each other. Fandom, as we can see here finds quite interesting the fact of imagine that both share more than "brotherly love" (aka. twincest) during their lives despite of being separated during 13 years.
- America and Canada, the "North American Brothers" of Axis Powers Hetalia, are (assumed to be) twins and pairing with growing popularity in the fandom. It can't match the popularity of the America/England pairing yet, but it has its devotees.
- Quite a few fans of Kira×Cagalli from Mobile Suit Gundam SEED refuse to follow the canon. Mostly because of all the Ship Tease between the two before The Reveal. Also because of the innocent purepure relationship between Lacus and Kira that does not seem to get any further than hugging or Holding Hands. And the relatively frustrating relationship between Everyone × Athrun × Cagalli that pushes suspension of belief.
- From Infinite Stratos and it's obscure Fan Dom, there's this (un)holy fic. Rather than picking one of the member of Ichika's Unwanted Harem, the author choose Ichika's Half-Identical Twins… who's clearly hots for him. The girl in question is The Dragon, M (Orimura Madoka), chosen specifically as O.C. Stand-in in an Alternate Universe Fic. She has a decent reason though. It's Crazy Enough to Work.
- Yoh and Hao in Shaman King are twins. In the anime, especially the 4Kids dub, Hao kept saying it was Yoh's destiny to unite with him. A lot of yaoi fangirls love Yoh/Hao. They are literally a single soul that got split in two, simultaneously explaining the "unite" Double Entendre and making this closer to Screw Yourself.
- Dipper and Mabel from Gravity Falls, due to the fact that they always hug or hold hands. In the fan community, the pairing is known as "Pinecest", after their last name.
- There are multiple examples of pairing up Netto and Rockman from Mega Man Battle Network/Mega Man NT Warrior. It's up to the Gentle Reader to decide which turns on or squicks him or her more—the game version, where this trope applies in full, or in the anime, where he's just a computer program.
- Amiboshi and Suboshi in Fushigi Yuugi, though a lot of this is fan speculation. Especially because Suboshi feeds Amiboshi a mind-erase drug through a kiss in episode 40. In an author's note in the manga, Yuu Watase claims that she didn't mean for that particular incident to seem so sexual. Suuure she didn't.
- The revelation at the end of Chrono Crusade that Chrono and Aion are twins hasn't stopped some fans from shipping them. The fact that Aion really does seem to have a brother complex doesn't help dissuade them.
- One of the fanon yaoi pairings in The Prince of Tennis involves a set of twins: the Kisarazus, namely Atsushi from Saint Rudolph (short hair, a red bandanna) and Ryou from Rokkaku (long hair, a white hat).
- There are a few fanfics that pair up opposite gender twins Android 17 and Android 18 from Dragon Ball Z 1 2 (Both of these stories are NSFW.)
- Many fans pair Vash and Knives from Trigun. To be fair, it is strongly implied that Knives has one heck of a brother complex towards Vash. The first big confrontation between Vash and Knives at the very end of the first Trigun manga really looks like a metaphorical rape scene complete with grotesquely obvious phallic symbols. Which wasn't even the most disturbing thing about this scene in the first place.
- The Kongo brothers pairing in Eyeshield 21 fandom has a pretty good following. Agon's a huge narcissist and Unsui is very dedicated to his younger brother. It's not hard to imagine it being a little more then brotherly…
- Twincest runs rampant in the Blue Exorcist fandom, with the Rin x Yukio pairing taking up almost 50% of all online romantic Fan Fiction (and normal boy x girl pairings less than 25%). Interestingly, there is no hint of yaoi in the actual series (especially since Yukio and Rin's relationship is… bad and getting worse mostly on Yukio's side). In fact, the most recent chapter (74) appears to have Kato half calling people out on it… she seems to be doing her best to remind the fans that this ship sank long ago (and never was there in the first place), though it's mostly Played for Laughs.
- Pretty much every The Boondock Saints slashfic.
- Harry Potter
- The Weasley twins are a prime example of this trope in fanfiction. Here is a good example. It's a song called "Brotherly Love" by Gred and Forge.
- Firebirds Son Trilogy plays on the Fred and George question; in it George is female and, while they are quite stated to be in a sexual relationship with Angelina and Lee, several characters have commented that the twins mother fears they would run off together. The fact that they are hyper sexual and extremely perverted (with Georgina confirmed to have had sex with Angela, and presumably Fred and Lee in foursomes) gives credence to this theory.
- After Rowling told the fans what happens to Luna, there's been a bit of twincest involving her sons Lorcan and Lysander. The fact that they aren't even mentioned in the books, and we know nothing about them other than that they're twins really shows how dedicated fangirls are.
- The Weasley twins are a prime example of this trope in fanfiction. Here is a good example. It's a song called "Brotherly Love" by Gred and Forge.
- In fanfics based on Lord of the Rings or The Silmarillion, Elladan and Elrohir are often shipped together. To a lesser extent, so are their father Elrond and his twin brother Elros, and Amrod and Amras, the twin sons of Fëanor.
- The Suite Life of Zack and Cody: Zack and Cody together have lots of fans, too.
- Devil May Cry: It doesn't help that Dante and Vergil are ridiculously pretty and there's a lack of female characters (that don't look like their mom.)
- Raul Gureden of Super Robot Wars Reversal would have fit the more appropriate Screw Yourself, due in fact his female counterpart Fiona Gureden are one and the same character in Reversal. However, upon getting an entry in Super Robot Wars Original Generation, the two became Half-Identical Twins; naturally, fanworks ascended it to this trope, even though continuity says otherwise.
- On learning that Fai of Tsubasa -RESERVoir CHRoNiCLE- has a deceased twin brother named Fai (hence why the Fai we know and love is named Fai), the fangirls hit the keyboards hard.
- In Xenosaga, Albedo is revealed to have been the conjoined twin of Junior. And let's just say that Albedo… was really obsessed with him, to the point where the thought of being unable to stay with him forever—among other things—drove him mad.
- A Alternate Timeline fanfic for the PS3 game In FAMOUS, in which the twin daughters of the first game's protagonist and Love Interest, Cole MacGrath and Trish Daily, become twincestuous lesbians; due to the nature of the fic, also possible candidate for Foe Yay and Power of Love.
- Lucas and Claus from MOTHER 3 have been treated in this way.
- Mario and Luigi from Super Mario Bros. have been given this by fans. Most slash fanworks are of them together.
- Mega Man 3: Gemini Man and his clones. It's one of the classic mainstays of Mega Man slash.
- Ask That Guy with the Glasses and The Nostalgia Critic are twins in fics most of the time, with Ask That Guy usually torturing Critic, sexually, emotionally and physically. Fun times for all.
- My Little Pony: Friendship Is Magic:
- A lot of fan art and fan fiction involving Aloe Blossom and Lotus Blossom loves to speculate about what goes on in their spa after hours (wink wink, nudge nudge).
- Fanon typically has Cloudchaser and Flitter as twins, though in canon it's unknown, but they're commonly shipped together.
- In The Two Between, though it isn't confirmed, Sunset is sure in-universe that the twins have a relationship of that nature.
- Edgar & Ellen fandom has quite a few of these.
- Transformers: If you see Sideswipe and Sunstreaker in a fanfic together, 90% of the time it's because they're banging each other.
- Likewise, Reflector now exists purely to have three-ways. But then three identical robots becoming one camera… really is asking for it.
- The jet twins Jetfire and Jetstorm too.
- Kyle and Lane Carlson, twin male models. And the Brewer twins, Derek and Keith.
- Thunder Cats: Both incarnations of WilyKat and WilyKit have gotten this.
- Hivefled; there's nothing actually going on between the Separated at Birth Gamzee and Feferi, but if they're caught, their Abusive Parents have plans.
- The Twins from Superjail! have somewhat of a fanbase that interprets them as incestuous based off their narcissism and closeness to each other. Certain lines (such as their "date" joke from an early episode) fueled the shipping, although the vague porn incident that traumatized them has been used by supporters and detractors of the ship to prove or disprove the dynamic being canon.
- Resonance Days has Arzt Kochen and Nie Bluhen Herzen, two identical witches (aside from differing Red Right Hands) who arrived in the afterlife together and seemingly cannot keep their hands off one another (much to the disgust of their teammates). Though they repeatedly claim that they aren't siblings, nobody believes them, and even they couldn't truthfully tell you otherwise thanks to Ghost Amnesia. It's actually a subversion; in life they were spinoff characters Yuuri Asuka and Airi Anri, the latter of whom wished to be identical in appearance to the former.
- Len and Rin from Vocaloid are constantly paired together, though Word of God says they're closer to selfcest as they were supposed to be mirror images.
- Pairing the two Ice Climbers together is common in Super Smash Bros. fandom. There's an ambiguity to whether they're siblings or unrelated friends though some shippers present them as lovers and siblings.
- The Rabbit And The Puppy Fanfic pairs Kagami and her twin Tsukasa. Yuri pairings are somewhat rarer.
- L and Beyond Birthday from Death Note are frequently portrayed as being twins (though whether or not they actually are twins, or even related to one another, is up for debate) and very often get into this. In most such works, BB coerces or forces L into it… but not always.
- There's Kinkaku and Ginkaku of Naruto. The characters aren't major, but if they were their twincest fandom may be higher. However, there have been fanfics in the past, and some fandom—in forums, and during chapter reviews, who toy with the idea, being that the two of them are constantly together, and they say each other's names in ever breath. It's canon that the word Ginkaku has said most in his entire life is his brother's name. And Kinkaku, while normally stoic and composed, manga-wise, flies into rage whenever his brother is seriously harmed. It also appears they stayed together their entire lives, and neither of them ever got married, or had any children. So there's room to toy with the twincest idea, and a few of the fandom has.
- Osomatsu-kun features a group of sextuplets. A lot of shipping between every pair, and sometimes even all six together, occurs. As mentioned above, the series itself made fun of this phenomenon.
- Max and Phoebe on The Thundermans, often called "Thundercest". Just don't tell it to Kira Kosarin, the actress who plays Phoebe, who is not a fan of the pair.
Films — Live-Action
- Stranz and Fairchild Van Waldenberg in Blades of Glory. The closeness of their relationship is a running joke throughout the movie and they even share a kiss at the end.
- Not-so-subtly◊ hinted at in Brothers of the Head with conjoined twin brothers.
- Cruel Intentions 2 had a scene where identical twin sisters make out in the shower. This film was originally produced as the pilot episode for a Fox TV series called Manchester Prep, but the series was cancelled before broadcast and so the pilot was "spiced up" for video release. One can safely assume this scene wasn't in the TV version. Rather ridiculously, in the scene the girls claim to only be cousins. This is one of only a handful of sexual scenes involving real-life siblings to appear outside of porn; as such, not only is it an R-rated example of Getting Crap Past the Radar, but it might be an example of the radar being turned off completely.
- The 1988 film Dead Ringers features some creepily sexual scenes between Jeremy Irons and Jeremy Irons as twin gynecologists Beverly and Elliot. It's based on the novel Twins.
- The Dreamers: An American student befriends a Parisian brother and sister Théo and Isabelle. They claim to have been been born connected at the shoulder, even though that can't happen with fraternal twins. It becomes more and more apparent that there is something very… odd about the siblings' relationship—heavily implied, though never explicitly confirmed, at the very least Isabelle was a virgin until Matthew—but our American doesn't really seem to mind. Everything's fine until someone puts a brick through the window.
- In Euro Trip, Jenny and Jamie get trashed on absinthe and make out (neither realizing who the other is). They are appropriately horrified when they open their eyes, and the next morning.
Cooper: Oh, here it is. Bratislava. Hmm. Capital of Slovakia. Oh, here's a fun fact: You made out with your sister, man!
- Subverted in Gone Girl: as the media circus surrounding Amy Dunne's disappearance escalates, the press deliberately starts spreading innuendo that Nick was having an affair with his twin sister Margo. Nick hears this trope invoked by name by a guy watching the news at an airport.
- Creepy Twins Wendell and Darlene from the horror film The Hamiltons.
- Hellboy II: The Golden Army: Okay, the twincest doesn't actually happen, but boy, does Prince Bishōnen Faerie want it to. It could be inferred that it had happened in the past. Considering that anything felt by one is felt by both, it's likely any masturbation experienced by one would automatically be shared with the other.
- In Hellraiser: Inferno, the Wire Twins Cenobites creep up on Joseph to have a deliberately disturbing make-out session with him and are seen feeling each other up in a later scene.
- Boy-girl twins Ryan and Sharpay Evans from High School Musical have twincest subtext… even though Ryan also has conflicting gay subtext. On twincest note, they have a suspiciously close relationship, what with singing love songs to each other and playing romantic leads opposite each other. There's Taylor's bizarre statement that, "If Sharpay could figure out a way to play Romeo and Juliet at the same time, her brother would be out of a job." Plus there's that video of "I Can't Take My Eyes Off of You", a song in which Troy, Gabriella, Ryan, and Sharpay all sing—Troy and Gabriella (established couple) sing to each other and Ryan and Sharpay… also sing to each other. Sample lyrics:
I can't take my eyes off of you
I know you feel the same way too, yeah
I can't take my eyes off of you
All it took… was one look
For a dream come true
- Pretty much the basic plot of The House of Yes.
- Very heavily implied with the twin socialite sisters ("We share everything") in Species II.
- Narrowly averted (at least according to Fanon) in Star Wars. The viewers (and the characters themselves) are initially led to expect a love triangle between Luke, Leia and Han, but then it is revealed in Return of the Jedi that Luke and Leia are actually long lost twins. Thee romance between them is vaguely Hand Waved, and the love triangle is instantly resolved.
- However, the novel Splinter of the Mind's Eye was written and takes place before their relationship was revealed and so features romantic scenes with the two, as well as a scene in which Luke openly admires Leia's body. Particularly her "seal-curve hips". Apparently Splinter of the Mind's Eye was George Lucas's plan B if Star Wars wasn't a big enough hit to make The Empire Strikes Back, and would have been developed into a movie had there been no money to make the trilogy as hoped. At this point, he had not decided whether or not Luke and Leia would be family or a romantic item, but with all sources taken into context it looks like a pretty clear case of Abandon Shipping.
- Marvel Star Wars, which also started production long before Return of the Jedi, also features a great deal of subtext early on. There are many, many instances between The Empire Strikes Back and Return of the Jedi in which either Luke or Leia were trying for a Relationship Upgrade when they were interrupted by something or other. On a meta level, it was because the writers knew Han would come back and show whether "I know" meant reciprocation, but looking at it today makes it seem like the Force knew these two were twins and contrived to keep them from sleeping together.
- New Jedi Order: The Yuuzhan Vong pantheon includes Yun-Q'aah and Yun-Txiin, sibling deities whose domain includes "love and hate and all things opposite". Their usual titles are either "The Twins" or "The Lovers". Thought it's possibly they either aren't twins or aren't lovers, and the Vong just have really confusing mythological canon—it happens. (For bonus points, a psyop plants a non-humorous meme in the Vong that the Jedi twins Jacen and Jaina are avatars of the twin gods…)
- In the 1969 British comedy Some Like It Sexy, a guy gets into a threesome with twins (played by former Playboy playmates Mary and Madeleine Collinson). After a little while he realizes the girls are paying more attention to each other than him, and when he moves away they don't even notice. He leaves and the girls continue without him.
- Billy Zane and Gina Gershon's characters in This World Then the Fireworks.
- The Acts of Caine: A probably nonconsensual example: Berne is revealed to keep twin sex slaves, one male and one female. This being Berne, if you think he wouldn't order them to have sex with each other, you plainly haven't read the books.
- The Duet evil twin rulers of the Seven Kingdoms in Morgan Llewellyn and Michael Scott's Arcana series.
- In the Arcana Chronicles series by Kresley Cole, the Lovers card is represented by brother and sister twins. They explicitly… yeah. Even more Squick when it turns out the twins seen before are idealized copies; the brother is ugly as sin, and the sister never really existed because all there is of her is a third eye in his chest from when he absorbed her in the womb.
- In The Bad Place by Dean Koontz, Violet and Verbena Pollard are twins and very… close. But it seems this kind of thing is par for the course in the Pollard family.
- Implied thanks to a Relationship Writing Fumble in The Belgariad. It's really, really difficult to read the opening few hundred pages of Polgara the Sorceress without reading some seriously odd romantic undertones into the relationship between (technically) non-identical twin sisters Beldaran and Polgara. Not only does Beldaran have her sister completely wrapped around her adorably girly little finger, but they're apparently sharing a bed well into adolescence whenever Polgara hasn't run away to live in a tree, and Pol's explicitly possessive anger when Beldaran gets engaged would be a little freakish in its intensity even coming from an actual romantic rival. (Technically technically, they are identical, making it even more fun. The physical difference or two comes from sorcerous manipulation in the womb.)
- Blue Bloods Novels: Twins Jack and Mimi Force are actually the angels Abaddon and Azrael, respectively, and are vampires who are "immortal twins"; that is to say they are bonded forever. This life cycle just happens to have them as blood relatives, which doesn't really seem to stop them—until Schuyler Van Alen steps in.
- In Book of the New Sun, twins Agia and Agilus are found to have an incestuous relationship when Severian enters Agilus' cell the day before his execution, only to find the brother and sister nude and huddled together. Agilus admits, "Everything you suspect is true," the implication being incest.
- Children of Dune has some pretty heavy overtones about Leto II and Ghanima's relationship at times. From Leto II's own mouth: "Let us pass puberty living in the same house, and all your taboos will be as a red rag waved in the face of a Sandworm." Perhaps mercifully, he undergoes transformation into a sandworm-like creature prior to puberty, thus removing this pairing from consideration. One of the reasons Leto transforms is to avoid the certainty of being maneuvered into this by the Bene Gesserit, who view this "ship" as the only way to get back control of their Kwisatz Haderach program after Jessica sabotaged it by giving birth to Paul.
…of course, this transformation doesn't stop Leto from marrying Ghanima later. But both of them are in complete agreement about the fact that there will be no weirdo hanky-panky going on, and that all her children will be bastards sired by a Corrino survivor, specifically the direct descendant of the emperor Leto's father deposed. (Though they're in love anyway, so, good for them.)
- Chronicles of the Kencyrath plays with twincest with two very different, but parallel, couples.
- It first shows up with Gerridon and Jamethiel, where it looks like Villainous Incest: They were twins, consorts, and the most infamous individuals in the entire history of their people.note But as the story goes on, the Villainous Incest gets Subverted—their twincest isn't portrayed as wrong or as part of their evilness. It was traditional and culturally sanctioned in their time, and their match was arranged by matriarchs trying to breed the chosen ones.note But because of their infamy, ever since Gerridon and Jamethiel, their people have mostly kinda stopped inbreeding—although the Ardeth still do. But because of the old tradition, their people now see incest—at worst—as a bad idea, not creepy or immoral.
- The second case is with the protagonist and deuteragonist, Jame and Torisen, a pair of Half-Identical Twins who are shaping up to be twincestuous too. By the fourth book, they're UST-y, and have had a few Erotic Dreams, and a Big Damn Kiss. (Word of God says yes, it'll eventually happen.) Few people know they're twins, and Jame once wonders, if people knew, whether they would throw them together to Invoke the trope, or make sure they never met again to Defy it.
In their case, twincest is symbolic of self-acceptance. The story plays with the idea of twins as foils, mirrors, other halves of each other. One of the big things keeping them apart is that Jame is a Differently Powered Individual in a world where that's considered dangerous and untrustworthy—and more importantly, so is Tori, but he denies it. She reminds him of this, and that's what really bothers him—much more than how this trait is present in her, but how it's present in himself. He can't be her lover until he accepts her, until he accepts himself.
- Half-Identical Twins Valraven and Pharinet Palindrake are lovers in The Chronicles of Magravandias. Pharinet justifies this by claiming that they are one soul in two bodies and that they are the last of a great heritage. They conceive a child, but Pharinet miscarries. That doesn't stop the relationship from destroying their family and their spouses.
- Elizabeth Lynn's The Dancers of Arun features male/male twincest between Kerris and Kel. Oddly, it's portrayed as wholly positive.
- In The Faerie Queene (1590) the giantess Argante commits twincest with her brother Ollyphant before they are born!! They mingle "in fleshly lust" before in the womb and emerge clasped in the act. Also, they're themselves the product of incest.
- Implied in Edgar Allan Poe's Gothic horror story "The Fall of the House of Usher".
- There's a rather bizarre example in Fifth Quarter. The soul of Bannon is forced to share the body of his twin sister Vree when another man steals his body. Vree goes after her brother's body, and when they find it, they devise a plan that Vree will distract him by seducing him, and Bannon will "push" the interloper out his body. Partway through, Vree realizes that Bannon is more interested in seducing himself than in getting his body back, and calls it off.
- A sister/sister version in the Gaea Trilogy. April and August Polo are very much a couple despite being identical twins—which the protagonist comments isn't very surprising given that they (and their seven other sisters) are all clones of their "mother" created after her death and raised in a lab with no outside friends.
- Ghoul: Rika and Saxon Hyde engage in twincest as teens. To amp up the Squick, they're the product of Brother–Sister Incest themselves.
- The God of Small Things: Twins Estha and Rahel deal with their Big, Screwed-Up Family eventually by shutting down, withdrawing from the world, and seeking solace only in each other. They no longer share the bond they once did, and the book ends with them trying to reconnect in the only way they feel able—through sex.
- Referenced by Nick in Gone Girl, though not to the same extent as in The Film of the Book; it's merely mentioned in passing.
[I]n high school, there were always rumors that we secretly screwed. Twincest. We were too tight: our inside jokes, our edge-of-the-party whispers. I'm pretty sure I don't need to say this, but you are not Go, you might misconstrue, so I will: My sister and I have never screwed or even thought of screwing. We just really like each other.
- Shelley and Kipling in Judith Hawke's Heart of a Witch get into a very complicated relationship that was hinted at from the beginning with Shelley's possessiveness of her brother. Even more weirdly, this eventually turns into a threesome with Snow, the leader of the coven that they join.
- House of Suns: A twist on this trope: The two protagonists are among thousands of both-sex clones of one woman. They are genetically programmed to be space-explorers, and all are supposed to meet once every 200,000 years to share information. Their progenitor forbid inter-clone romantic relationships and, while sexual encounters are said to occur occasionally, the protagonists' long-term consorting is strongly rebuked by their fellow "siblings."
- In Death: Rudy and Piper Hoffman from Holiday In Death are fraternal twins and longtime lovers. Rudy has admitted that they have tried not to act on the attraction between them and be with other people, but they were miserable because they're attracted only to each other. Piper even had herself surgically sterilized, with Rudy's encouragement. Eve, herself a victim of incestuous rape by her father, is highly squicked out by this, and there are some indications that the relationship has taken a toll on Piper mentally (though it's not entirely clear how much of this is projection on Eve's part).
- The Journeyer has a pair of twin lovers, Biliktu and Buyantu. It doesn't end well.
- Kire: Jerkass Ørjan is a Shipper on Deck of Trine/Tore much to their and their friend Erik's annoyance. He constantly prints out lists of where siblings can get married.
- In Donna Tartt's The Secret History, Bunny Corcoran references this trope when he suggests that twins Charles and Camilla Macaulay, who share an apartment, are in it for less innocent reasons than just to save money. This offends her greatly and leads her to comment, "You mustn't think I'm sleeping with my brother just because I won't sleep with you." He's right, though, and it's been going on for years.
- A Song of Ice and Fire:
- Cersei and Jaime Lannister (the Lannincest). An unusual example of an incestuous relationship in serious fiction, as their affection for each other is depicted as genuine, unforced by either partner, long-term, and stable... at least when the story opens. Jaime is revealed to be true father of Queen Cersei's children, thus making them false heirs to the throne. This eventually causes civil war to break out, and the situations it puts Cersei and Jaime into gradually begin to force them apart. It only gets worse when it's revealed that they were into each other even as little children—their mother walked in on them doing something sexual when they weren't even ten years old. In Cersei's mind, the bond goes back to their birth, seeing as the two shared a womb and Jaime came out holding onto Cersei. Some readers also think that narcissistic Cersei sees their relationship as the closest she can get to Screw Yourself.
- Twins Aelor and Aelora Targaryen were married, which wasn't unusual, since their family practised incestuous marriage regularly. Aelora caused Aelor's death somehow, and she was driven mad with grief over this fact.
- Stalking Tender Prey by Storm Constantine has, within the first few chapters, a pair of Half-Identical Twins who, because they are hybrids of human, and a very oversexualised variation on the Nephilim, and the only two in the area, and therefore can only express themselves to each other get into twincest an awful lot. Although—let's be fair—most of the main characters do bedhop with most of the other main characters. In fact the main antagonist, as the fallen angel, effectively satan pretty much gets to bonk 98% of the main characters. Repeatedly.
- The Thirteenth Tale: Emmeline and Adeline's relationship has very strong incestuous overtones.
- Time Enough for Love: Protagonist Lazarus Long relates a story about a twin brother and sister he encountered who were unrelated to each other through a remarkable feat of genetic engineering, and were induced from childhood to form a sexual bond with one another for breeding purposes. As they are slaves, he buys them, frees them, and sets them on the road towards being independent human beings, but they still end up marrying each other and pumping out babies.
- Thomas Mann's novella "Wälsungenblut" features Siegmund and Sieglind, twins who seem to go everywhere holding hands, and spend a good chunk of the story attending a performance of Wagner's Die Walküre. Everything goes as expected.
- Played for Laughs in Another Period. Beatrice and her twin brother Fredrick are in love and regularly have sex, despite the fact Beatrice is married (to a gay man who also has a lover and who happens to be married to Beatrice's sister). One episode has Freud (yes, that Freud) trying to cure Fredrick of his supposed homosexuality. When he sees him having sex with Beatrice, he feels the treatment worked, and is unphased at Fredrick being with his sister.
- In the final episode of Arrested Development its revealed that Michael's twin sister Lindsay is adopted. Her almost immediate reaction to learning they're not related is to try and convince him to marry her. Later Gob comes on to her when he learns about this. She punches him.
- Beastmaster had a fraternal twin example in its first season.
Tao: It says you were born in the same place… and at the same time.
Gem: You are the first to understand.
Tao: This has to be wrong.
Nye: It's not wrong.
Gem: We know our own story.
Tao: But it says you were born of the same mother.
- Degrassi: The Next Generation: Twins Declan and Fiona Coyne were introduced in season 9 as being "very close." In Degrassi Takes Manhattan Fiona drunkenly kisses Declan at a party in front of everyone to make Declan's girlfriend jealous.
- Cersei and Jamie Lannister in Game of Thrones, the television show being a faithful adaptation of A Song of Ice and Fire (see Literature above). From the DVD Commentary for "The Kingsroad".
Lena Headey: Now this is the scene of a previous crime, double misdemeanour…
Mark Addy: Yeah, a crime against humanity, really…
Lena Headey: Twincest… which is a lovely phrase.
Nikolaj Coster-Waldau: It's a great phrase! Twincest…
- Glee: Heavily lampshaded—though subverted—with Mason and Madison McCarthy. Apparently the Cheerios have had to tell them that Flowers in the Attic is not a good example for a relationship, and during the "Home" performance in "Homecoming", Mason sings the line "Boy I love my ma and pa / Not the way that I do love you". Kitty explicitly compares them to Jaime and Cersei Lannister. Madison's Clingy Jealous Girl behavior comes off as very twincestuous, until we find out that it's actually because she's always been a Parental Substitute to her brother, since their actual parents are always out performing rather than being parents. Madison and Mason work it out, and she backs off.
- It's impossible to watch Maya and Alejandro Herrera in Heroes without thinking about it. After all, Maya killed everyone but Alejandro and herself during her twin brother's wedding after she learned that his bride to be was cheating on him… Probably a Relationship Writing Fumble.
- There was a pair of fraternal male twins that the main characters used to go to school with on It's Always Sunny in Philadelphia that were sexually involved. Turns out the entire McPoyle family is one large, ingrown incestual orgy. It's just about the creepiest thing on television.
- In "Who Got Dee Pregnant," the gang (minus Dee) think that Dennis was the one who had sex with Dee at the Halloween party (due to Dennis switching costumes with Charlie and Dee with the girl Dennis was trying to hook up with). Dennis is throwing up when they confront Dee, with them telling her she has to go to Mexico to get an abortion—which she states none of them are the father and although she pulled Dennis into the back room, they didn't have sex.
- It took twelve seasons, but Law & Order: Special Victims Unit finally went there in the episode "Bombshell": Guest-star Rose McGowan played a con artist/swinger who was swindling people with her twin brother—and also sleeping with him because they "share a soul." Elliot even calls the trope by name. It was one of the few things that genuinely managed to shock the seasoned SVU detectives.
- In an episode of Medium, some characters come across a porno that features this.
- The show runner of Riverdale also worked on Afterlife with Archie, and the idea of twincestuous Cheryl and Jason Blosson has carried over, even with Jason being a Posthumous Character. The aesthetic of twincest is played with a lot. In the opening scene (their Establishing Character Moment) Cheryl and Jason are framed like a couple: Wearing coordinated clothes, holding hands, going on what looks like a Old-Fashioned Rowboat Date, all with a love song paying. Cheryl once describes Jason as her "soulmate". They are seen in a flashback Sweetheart Sipping. After loosing him, Cheryl is referred to as a "Red Widow". There also shades of twincest in Cheryl's interest in Archie, because Archie resembles Jason so much. In episode 10, it's actually called out by in-universe by Veronica, who attempting to turn around Cheryl's attempt to bully her and the rest of the gang. However, those accusations appear to made up on the spot out of spite, not based on any concrete evidence. And despite this aesthetic, it seems that they weren't actually a couple: Jason was determined to be with his third-cousin Polly.
- Implied with Katie and Emily Fitch from Skins. Whether this is a Relationship Writing Fumble or intentional really isn't clear. Moreso Katie than Emily; she states that Emily is "hers" and Naomi—Emily's girlfriend—could never love Emily as much she does. It doesn't help that at one point during the end of the twins' episode in series three, when Emily is confronting Katie, someone in the crowd yells out that Emily should kiss her. And in the book, the Fitch family are on holiday in France, and Katie steals Emily's phone so she and Naomi can't stay in touch.
- In Witches of East End an episode had villains Ivar and Isis who casually mentioned they were twins after making out in front of Freyr. Freyr even uses the phrase twincest to describe it.
- Definitely played with by John and Edward in The X Factor, such as their routine to "Oops I Did It Again", which involved a full re-enactment the talky bit between Britney and her love interest from the music video ("but I thought the old lady threw it into the sea at the end of the movie"). For anyone masochistic enough to want to see them in action, here is the aforementioned performance.
- Made explicit in Le Sexoflex's cheerfully NSFW song "Twincest". The music video features male and female twins gettin' it on with their siblings, animated by pornographic embroidery.
- Implied when The Veronicas, a band consisting of twin sisters Lisa and Jess Origliasso, sing "All About Us", a song that, while written by them, was made famous by t.A.T.u., apparently Schoolgirl Lesbians. The story goes that the song was originally a demo done by the Veronicas; when they couldn't fit it into their lineup, they handed it over to t.A.T.u. Which is not to say that the Veronicas are not twincestuous as hell—see their propensity for taking ridiculously inappropriate-for-sisters pictures. Seriously. Not to mention their music videos. No… THIS video. Also this is the official video for the first link… and a little more twincest sexy
- And at least one of them is rumoured to be a lesbian, which would presumably fuel such speculation.
- Similarly, when Ryan Dan (another twin band, of the male variety) sing mushy romantic duets to one another. Well, at least one can sing soprano very well.
- More willfully-interpreted Ho Yay: Bill and Tom Kaulitz,◊ of German band Tokio Hotel.(New .gif for your pleasure! More lap-bouncing, less arm-tugging)
- So… much… fanfiction… It's staggering how… [http://salv.deviantart.com/gallery/ dedicated]] these fangirls are.
- At least once when performing live Bill has dropped to his knees in front of Tom, while singing a song supposedly about Tom and a groupie. More specifically, he sang "Ich will mit keiner ausser Dir." Which roughly, in context, translates to "I don't want to do it with anyone but you." He always sings that part to Tom.
- Unfortunately, though, "keiner" denotes a female "anybody" (the male form would be "keinem"). Which either rules out the homosexual context or says things about Tom we'd better not go into.
- Bill has also commented on these stories saying: "Everybody can have his fantasies… though they are sometimes really absurd… but they do exist for that…" Hmm-HMMM.
- "I'm ready to fall, I'm ready to crawl right on my knees to know it all." Practically on his knees in front of Tom while admitting he's okay with being down there? Oh Bill, learn some subtlety.
- This seems to be the gist of the relationship between the Kagamine twins of Vocaloid, at least among the fandom. Though they look like twins, Crypton originally presented them as such before making them "mirror images," then finally telling the fans to decide for themselves.
Myths & Religion
- In traditional Bali culture, fraternal twins (known as kembar buncing) are assumed to have had sex in the womb. If they were born to a poor family, their entire family would be thrown out of town for 42 days and all religious ceremonies would be called off for that period. If they were born to the royal family, however, they would be betrothed to each other.
- Classical Mythology: In Ovid's Metamorphoses, the story of Byblis and Kaunos is a one-sided case. While Byblis likes him, and admits her feelings, he is completely disgusted by her affection.
- Egyptian Mythology: Osiris, Isis, Set, and Nephthys were all quadruplets who fell in love while still in the womb together, forming two couples: Osiris/Isis, and Set/Nephthys.
- In the Feri Tradition (one of the Neo-Pagan movements), there is a pair of twin gods who basically share all aspects of themselves with each other (and not just in that way), or so claims The Other Wiki. They also don't have a fixed gender.
- Norse Mythology:
- In "Lokasenna" of the Poetic Edda, Loki accuses Freyr and Freyja, the sibling fertility deities, of sleeping together, though it's unclear whether this is "truth" or not.
- In the Völsunga saga, Sigmund is seduced by his sister Signy in disguise, as she believes only in this way she can conceive a son that is strong and loyal enough to help Sigmund avenge their brothers and father on their killer, Signy's treacherous husband Siggeir.
- The Sioux say twins are the reincarnation of lovers. Whether Everyone Is Bi or Unto Us a Son and Daughter Are Born is another issue.
- In 2003, Shane and Sia Barbi sued Hustler for unauthorized use of photos showing "intimate sexual acts between the twin sisters".
- Bat Boy: The Musical: Bat Boy and Shelley… and it's an Interspecies Romance too!
- The entire plot of the rather strange—and very sexual—British queer play Over There. The two-man cast consists of the identical twins Harry and Luke Treadaway, and I can only say that the two certainly aren't uncomfortable with each other.
- This trope (along with a helping of Creepy Twins) is the premise of Marina Carr's play Portia Coughlan. Portia is haunted by her twin brother Gabriel, who drowned himself as a teenager; the fact that she's still obsessed with him fifteen years later (and that Gabriel is referred to as "unnatural") hints heavily towards this, so it's no surprise when she reveals that their relationship was sexual. It's a bit more surprising when her aunt reveals that Portia's parents, too, are half-brother and sister, though neither of them know it.
- Part 2 of Richard Wagner's operatic Ring of the Nibelung cycle, The Valkyrie, has Siegmund and Sieglinde: Twins separated at birth, who meet as adults and fall in love with each other. It looks like it's setting up to be Surprise Incest, but then subverted when they realize they're twins, but go ahead anyways. Sadly for them, Fricka—goddess of marriage—is very opposed to twincest and adultery. (Adultery because Sieglinde is married, though it was a forced marriage.) Having a goddess against you is never good news, and Siegmund ends up being killed. But Sieglinde is pregnant, an de gives birth to the legendary hero Siegfried.
- This trope (actually done sympathetically) is the centerpiece of John Ford's ever-controversial 'Tis Pity She's a Whore. Unusual in that the creepiness of the setup comes from a) how similar it is to a regular love tragedy, and b) how its lack of acceptance leads Giovanni to snap and rip out Annabella's heart.
- Per usual tradition, Fire Emblem doesn't exempt from this in the case of the eighth series, The Sacred Stones. Doesn't go with the usual route (their ending put them in the position of Platonic Life Partners), but the plot, other characters' reactions, and even symbolism all point to twincest vibe between co-protagonists Ephraim and Eirika.
- Resident Evil – Code: Veronica implies that Alfred's devotion to Alexia goes some way beyond mere intense admiration.
- The novelization pretty much states it outright.
- Yosuga no Sora is the embodiment of this trope with the male lead Haruka having such relationship with his very twin sister Sora. Among the both of them, Sora was shown more crazy and obsessed with her brother as she constantly fantasizes having sex with him and gets jealous when Haruka interacts with other females.
- Metal Gear Solid, being chock full of Ho Yay moments, certainly didn't shy from playing with this trope. Liquid Snake strips Solid Snake's shirt off while the latter was unconscious, and there was his desperate need to prove that he was the dominant brother. Naturally, it's kicked up to overdrive in the remake. It also certainly didn't help that Liquid was a Large Ham and his voice actor, Cam Clarke, seemed to have an uncanny ability to make the word "brother" sound very erotically incestuous.
- Liquid does blatantly say that part of his motivation is that, "in Nature, family members don't mate with each other, but they help each other to survive." Bad biology aside, it's pretty easy to overthink how that would justify him killing his brother instead of 'helping him to survive'
- In Metal Gear Solid 4, when Snake and Liquid are having their final fight, if Snake can't shake liquid off, Liquid will kiss Snake's cheek. However, at the time, Liquid is possessing the body of Revolver Ocelot so YMMV on the level of twincest. Subverted in the fact it's really just Revolver Ocelot impersonating Liquid. The matter is further complicated considering Ocelot had a crush on Snake's identical clone "father", Big boss, which adds Love Father, Love Son into the whole mix. The whole thing can be rather… confusing. Then again, it wouldn't be Metal Gear Solid if it wasn't.
- Fatal Frame II: Crimson Butterfly, with their whole "becoming one with your other twin". One of the key plot elements of the game is the fact that the village use to perform rituals in which the older twin would strangle the younger one, who would then become one spiritually with the older twin and then they'd get to be togeetheeer foreeveeer. This whole "I want to be with only YOU, [insert other twin's name here]!!" thing happens with pretty much all of the Twin Shrine Maidens depicted in the game, including but not restricted to Azumi and Akane Kiryu, the protagonist Mio and her sister Mayu, and the antagonist Sae with her sister Yae. Sae seems to be the one with the most weirded-out obssession with her sister, since she seems to all along have fantasized about the day that she'd get to be strangled by Yae by the end of the game you find a crystal left by her that is pretty much along the lines of "Oh Yae, kill me, KIIILLL MEE" like she's getting turned on by the idea.
- Not to mention in the promotional comercials, Mio and Mayu are shown in a number of amusingly suggestive poses together. The strangling pose Mio puts herself in above Mayu at the end of the game in Normal mode is also very suggestive.
- In King's Quest III, after Alexander frees his twin sister Rosella and talks to her, he seems attracted to her in a not-so-platonic way. Of course, they were also Separated at Birth.
- The same reason was why a lot of Phoenix Online players were scratching their heads at the opening scene of The Silver Lining (a Fan Sequel to the series). Sure, it makes logistical sense to keep the comatose twins in the same room where their respective spouses can act as a final line of defense… but the same bed?!
- Weiss and Nero from Dirge of Cerberus.
- Amber and Crystal Bailey in Dead Rising 2. Then again, they both hit on Anything That Moves.
- Lucjan and Myaja, a brother-and-sister fighting team in Dragon Age: Origins, state that "everything they do, they do together." When the PC asks them if that means everything, Myaja asks if he wants to find out.
- Duke Nukem Forever has the "Holsom Twins".
- In The Sims 2, if you turn off the switch that prevents incest relationships, twins fall in love very easily, without intervention from the player. Mechanics-wise, it is probably due to their interests and personality traits being alike, therefore making the "perfect" match as far as the game is concerned.
- Crossing over with the Screw Yourself trope there's Morrigan and Lilith Aensland from Darkstalkers. Lilith is a shard of Morrigan's soul but she has been given a separate body. Being Horny Devils that survive on pleasure sorta justifies their relationsip.
- Similarly to the above, the Lutuces from BioShock Infinite, which crosses into Screw Yourself given that they're genderbent versions of the same person.
- A rather bizarre example in Drakengard 3. One's Disciple (basically a bodyguard and a consort combined) is an Opposite-Sex Clone of herself that she created. The clone is addressed as her "Brother" and while they don't do it in the game, the short stories written for the game confirms that they were intimate.
- The relationship of twin sisters Sako and Yuko Katagi of Criminal Girls has elements of Incest Subtext, particularly in regards to Sako and her constant concern for Yuko's well-being. It turns out that Sako has one-sided romantic feelings for Yuko.
- Fraternal twins Lucy and Fisk in Better Days. Whether it happened more than once is a matter of debate. Lucy at least continues to have more than sisterly feelings for her brother well into college.
- Given that there are several early Naylor porn-folios centered around Lucy and Fisk, it seems likely that they were at least originally intended to have a long-running relationship (as their counterparts in Badly Drawn Kitties did until his departure) …but then again, those portfolios are stricken from the record as far as Naylor is considered, mostly because the copyright notices affirm that Lucy is not his original creation.
- Heavily implied of the Subway Masters in Black Adventures (the Subway is not affected by a power outage because "it runs on our bruderliebe"), and accidentally the case for Black's crush on White when she's revealed to be his twin. In the latter case, it's used for Ship Sinking rather than titillation.
- Rick and Kate in Concession, though that is not by any means the only way they are messed up. Also Joel's connection to his sister's ghost seems to border on this, though she died too young for anything to really happen.
- The twin lawyers in DevilBear have a strong vibe of this going. Given that they are infernal servants and borderline Horny Devils, it's not unexpected.
- Invoked with Jasprosesprite^2 and Davepetasprite^2 in Homestuck. The Rose and Dave parts of them are just as squicked by the idea as the "main" Rose and Dave would be, but they acknowledge that cats don't worry about that sort of thing and trolls are born from an "incestuous slurry", so the Jasper and Nepeta parts don't see the problem.
- Succubus twins Giselle and Alizee in Leth Hate, although not voluntary on Giselle's part.
- Hiroki and Masuji from Seiyuu CRUSH! are hinted to have a more-than-brotherly relationship, and this is confirmed in scene 13.
- Both entirely averted and parodied in Critical Role. The Half-Identical Twins Vex and Vax almost never get shipped with each other in the fandom, and the topic only comes up once in-series, when Vax is discussing his love interest, Keyleth:
Vex: (clearly jealous) Yes, yes, Keyleth is so fucking beautiful, I get it.
Vax: Well so are you, but what the fuck am I gonna do with that? Geez, you're fucking weird!
- Fanart of Happy Tree Friends Raccoon Twins Lifty and Shifty getting really, really close is unsurprisingly popular, especially Gijinkas. Shifty is the one with the hat.
- Whilst nothing explicit has happened (Yet?), Survival of the Fittest V3 characters Lenny and Elizabeth have a whole lot of Subtext in their relationship, prompting a lot of "speculation" amongst members of the board. It isn't clear precisely what relationship the pair have, but it is implied it goes further than being simply siblings. Recently the handler more-or-less addressed this issue, quoting a Fanfic in this first half of one of his posts.
- In Tea, Biscuits and Incest, Makayla finds out that her ex-boyfriend Jayden is her long-lost twin. Doesn't help that he's also sleeping with their father.
- A lot of fanart depicts Hacchan and Secchan, the Moe Anthropomorphisms of Windows 98 First Edition and Second Edition respectively, together. This one's safe for work, but most others aren't. And even those that don't depict the 98 twins being mutually attracted to each other often have Secchan acting Yandere for Hacchan.
- A vast thread on the RPGNet forums, covering creepy gamers, had a poster effectively troll the discussion by promising to elucidate on a story of creepy gamers that involved twincest. Although there were several Crowning Moments of Awesome and Funny involved on the thread as it was, the rumoured story turned out to be disappointing, though it did get an airing.
- Andy and Ollie Pesto of Bob's Burgers are prepubescent but definitely headed in this direction.
- Robot Chicken
Leia: That was so wrong.
- The show has a long running gag portraying the Bush twins, Barb and Jenna, as hard-partying Girls Gone Wild types, often ending with the two of them making out.
- During the Star Wars special, there was the inevitable skit involving Luke and Leia in bed.
- In "The D'oh-cial Network", an episode of The Simpsons, the Winklevoss twins make a brief cameo, in which they compete against Patty and Selma at the Olympics. The scene ends with Cameron and Tyler making out.
- Invoked in Young Justice. Superboy and Miss Martian go undercover as two twins. While in their disguise they make out, and it takes a while for the latter to transform back into her normal self. Much to the horror of Icicle Jr.