History Fanon / AnimeAndManga

*** While Secco appearance while not wearing Oasis is never shown, fan art tends to portray him as having messy blue hair, similar to the stitches on Oasis' eyeholes.

*** DIO's henchmen (especially Hol Horse, Mariah, Midler, and the Egypt 9 Glory Gods) are often portrayed as friends during their downtime.

*** Jotaro is believed to have met his wife in college, and that she is a fellow marine biologist. Fan works that give her a name tend to also follow the series' MusicalThemeNaming by naming her either [[Music/DollyParton Dolly]] (since Jolyne is named after a Dolly Parton song) or [[Music/MarinaDiamandis Marina]] (as a [[PunnyName pun]] on her husbands love of the ocean).
*** The only hint regarding Pucci's ancestry is that his great-grandmother is from Venice. A lot of fans like to interpret Pucci as being of Sicilian descent, usually as a way to explain why he has noticeably darker skin compared to the rest of his family. The anime adaptation giving his father dark skin helps support this idea. On a similar note, the fact that [[spoiler:the racist private detective Pucci hires doesn't seem to take issue with Pucci's dark skin appearance is usually explained away by the idea that Pucci's wealth and his status as both a priest and a respected member of their community means that he's far to risky of a person to take action against]].

* Thanks to an EyeCatch from the third season of ''{{LightNovel/Slayers}}'', just about every fanfic writer believes that Luna Inverse and The Beast Master, one of the five Dark Lords under Ruby Eyed Shabranigdo, are best friends. This seems to stem mostly from a mixture of the manga (which revealed that the werewolf/troll crossbreed Dilgear did, indeed, heal from his fatal wounds and ended up becoming Luna's pet) not being very available and Luna's willingness to [[GoodIsNotNice pass off saving the world and claim she was too busy being a part-time waitress]], instead insisting that they approach her... [[ChaoticNeutral "unpredictable"]] little sister instead. This is despite Luna being known to carry the soul of the chief ''god'' of their world within her, essentially making her a Paladin of such power she can kill a dragon with a kitchen knife and a natural enemy to all Mazoku.

* It's a commonly known fact that the protagonists of ''VisualNovel/{{Tsukihime}}'' and ''LightNovel/TheGardenOfSinners'', Tohno Shiki and Ryougi Shiki respectively, both of whom can see the "predetermined death of all things" can only see the deaths of those with a "Gaian concept of death". Except this isn't fact; it's a theory created by English-speaking fans based off something written in the side materials: Specifically, that neither of the Shikis can kill ORT, the Ultimate One from the planet Mercury (otherwise known as TYPE-MERCURY). The reason that neither of the Shikis can kill ORT is because it literally does not have a "death", at least not one that either of the Shikis can recognize. According to Word of God, TYPES like ORT cannot be killed, even if you eliminate their physical bodies, as they don't have a concept of life or death to begin with. Fandom has run away with this, claiming that the reason neither of the Shikis can kill ORT is because it is not from Earth.

* ''LightNovel/MariaWatchesOverUs'':

* Mashiro from ''LightNovel/ThePetGirlOfSakurasou'' is never stated to have any sort of neurological or mental disorders, but amongst at least western fans she's considered to be on the autism spectrum.

** A surprisingly popular theory among fans is that Hol Horse is Mista's father. This likely stems from both having Stands based that allow them to control the direction of their guns' bullets (as well as both having the tendency to end up getting hit by their own bullets), as well as Hol Horse's mercenary occupation and status as TheCasanova who claims to have "girlfriends all over the world" making it entirely possible that he's been to Italy. The fact that Mista was born in 1982 and Hol Horse appears to be in his late 20s or early 30s in 1989 means that the timeline matches up as well.

** The trip the Astons took to visit Fanelia that Millerna remembers in episode 6 was to possibly arrange a marriage between one of the Asturian princesses and one of the Fanelian princes.

*** Ghiaccio and Melone are often portrayed as being VitriolicBestBuds with a RedOniBlueOni dynamic, an idea that is somewhat showed off in anime's extended flashback of La Squadra's backstory. Some fans also like to joke that the reason Melone's {{catchphrase}} is the grammatically-incorrect [[GratuitousItalian "Di molto!"]] is because he's intentionally trying to piss [[GrammarNazi Ghiaccio]] off.

*** DIO's henchmen (especially the Egypt 9 Glory Gods) are often portrayed as friends during their downtime.

*** Fan works focusing on La Squadra usually portray the group as having a family-esque bond, with Risotto in particular being portrayed as a TeamDad.

*** Ghiaccio and Melone are often portrayed as having a RedOniBlueOni dynamic.

*** Jotaro is believed to have met his wife in college, and that she is a fellow marine biologist.

** Any attempt to explain Hiltz' IdiotPlot master plan from ''Guardian Force'' will inevitably involve fanon speculation, given both the nonsense plan and Hiltz' acute lack of personality.

*** Because Sorbet and Gelato were [[PosthumousCharacter killed off prior to the events of the Part]], fans like to fill in their personalities and relationship with the other La Squadra members. Most commonly, the two are portrayed as having non-combat based Stands, Sorbet is portrayed as a KnifeNut while Gelato uses firearms.

* ''Manga/DemonSlayerKimetsuNoYaiba'', the last manga volume was released in December 2020, Japan, and even after a 2nd Databook got released in 2021 some character backgrounds remained with some unexplained details, with that some fans assume certain things:

* In just about every ''Literature/SoundEuphonium'' fanfic, Kumiko is lesbian and Reina is bisexual. The two have a RomanticTwoGirlFriendship filled with heavy HomoeroticSubtext, but it never goes anywhere. In the original book, Kumiko has a male love interest but all romance between the two were written-out of the anime (instead it became unrequited). Reina is [[TeacherStudentRomance in love with her music teacher]], which is why fans see her as bisexual rather than lesbian. Yuuko and Natsuki are also pinned as gay (and are almost always shipped together)

** Another common one is that Nyamo and Yukari are an item. Or, alternatively, that they ''were'' one. This appears to have most basis in the fact that [[HeterosexualLifePartners they are still single]] and that Nyamo still puts up with Yukari's [[{{Jerkass}} insults]] and [[SenseiChan childish behavior]]. More observant fans often cite Nyamo's drunken lecture about "adult relationships" and the [[NoodleIncident love letter]] Yukari teases her about; since it's later explained that they both attended an all-girls' school, [[SchoolgirlLesbians it's easy to fill in the blanks]].

* Suna as an (often [[CelibateHero aromantic]]) {{asexual|ity}} is a frequent headcanon in the ''Manga/MyLoveStory'' fandom.

*** While Kakyoin's comment about wanting to marry someone like Holly was more likely meant to refer to her NiceGirl personality, pretty much the entire fandom decided to take it a completely different direction and instead portray Kakyoin as a [[LikesOlderWomen MILF-hunter]]. Kakyoin is also commonly portrayed as being romantically interested is Jotaro, despite the two [[ShipsThatPassInTheNight interacting very little during their time seen together]].

** ''Manga/VentoAureo'':

* ''Manga/DetectiveConan'': In canon, Conan occasionally orders iced coffee from restaurants. In fanon however, he's interpreted to be addicted to coffee, usually drinking it black.

** EveryoneIsGay, no ifs, ands, or buts. Sometimes Eriko gets pinned as bisexual but the rest of the main girls are lesbian.

* In ''Anime/MaiOtome'' fanfiction, the Aries Republic government building is commonly called "the Hexagon", as its design is a clear reference to the real-life Pentagon that houses the US Department of Defense, but with six sides.

* ''Manga/DetectiveConan'': In canon, Conan occasionally orders iced coffee from restaurants. In fanon however, he's interpreted to be addicted to coffee, usually drinking it black.

* In the ''Manga/{{Guyver}}'' fandom, it's generally accepted that Edward Caerleon, late of the [[TheOmniscientCouncilOfVagueness Zoalord Council]], is Welsh.

* Though ''Anime/GunXSword'' fans are divided as to which member of his harem would have been best for Van, most of the existing romantic fanfics pair him off with Wendy [[spoiler: especially the continuation fics that are set after the show's MaybeEverAfter ending, when a Van X Wendy relationship wouldn't be lolicon]]. Interestingly, several different pieces of continuation fic also assume that [[spoiler: Wendy]] works in a hotel or restaurant after the end of the series, despite there being no direct evidence of this in DistantFinale.

* Even fluff anime isn't immune. ''Manga/AzumangaDaioh'' has all sorts, ranging from ungiven names (Sakaki, Kagura, Kaori, and Chihiro all only have one name given) up to unrequited crushes (remember, only ''one'' is actually shown). Add generous desire for LesYay and stir:
** Two of the fanon names are Kaori '''Aida''' and Chihiro '''Inoue'''. This is based off a panel of the manga, where characters we see the back of the heads of are called these surnames and the backs of their heads ''kinda'' look like Kaori's and Chihiro's. Sakaki or Kagura don't have any commonly agreed-upon names, though, and it isn't even agreed if they're family names or given names. Occasionally, even the nameless background extras are given fan names, as is the case with Rachel Handlebars.
** A very common belief is that Osaka has forgotten her real name is Ayumu Kasuga. This was never actually seen in either manga or anime, instead being taken from the ''Tsunami Channel'' webcomic. In fact, at one point she freaks out upon discovering that she isn't listed on Miss Yukari's class roster, because she was looking for her birth name. Yukari put her down as "Osaka".
** Another common one is that Nyamo and Yukari are an item. Or, alternatively, that they ''were'' one. This appears to have most basis in the fact that [[HeterosexualLifePartners they are still single]] and that Nyamo still puts up with Yukari's [[{{Jerkass}} insults]] and [[SenseiChan childish behavior]]. More observant fans often cite Nyamo's drunken lecture about "adult relationships" and the [[NoodleIncident love letter]] Yukari teases her about; since it's later explained that they both attended an all-girls' school, [[SchoolgirlLesbians it's easy to fill in the blanks]].

* On a great many fansites for ''Manga/ElfenLied'', Silpelit Number 3, who infected Kurama causing him to sire Mariko as a Diclonius, is supposed to be the older sister of Nana. There is no evidence for this. It appears to be a mistake one person made that was then lifted literally verbatim on each successive site.
* ''Manga/FushigiYuugi'' has a couple of typical fanon elements that came up much more often in the high days of the fandom, but persist in the fanfic that still exists, despite most of it being Jossed by the addition of ''Genbu Kaiden'' and the novels published after the anime ended:
** Ashitare (if he's not dismissed entirely) is written as having a full human form that is as {{Bishonen}} as any other guy in the manga, but this doesn't happen often because Ashitare is mostly undeveloped as a character.
** Tomo and Soi are assumed to hate each other and are love rivals over Nakago; they're not, and they don't. They actually work very well together the one time they're shown doing so. If they aren't written as hating each other, they're usually friends instead, having bonded over having been sexually abused as children (canon in her case, fanon in his). In the same vein, Tomo's real name is usually given as Ruo or Ryo Chuin; the novels name him Ragun.
** Before ''Genbu Kaiden'', Uruki of the Genbu Seishi was usually written as a woman in fanfic because of the star Uruki is represented by. Hilariously, Uruki is a man... who [[GenderBender must change into a woman]] to use his wind powers.
** Whether Nuriko was in love with Miaka romantically or loved her platonically was a subject of fierce debate; the answer depends on whether you're a YaoiFangirl or not.
** Mitsukake (if he's mentioned at all) is sometimes written as having been a military doctor, usually leading to him [[TakeALevelInBadAss getting a power upgrade]]. The rest of the time he's a pacifist with [[WhatKindOfLamePowerIsHeartAnyway lame healey-bubbleys]], which conveniently forgets that his healing powers also exorcise demons.
** Hikitsu and Tomite were often written as brothers.
** Tasuki doesn't like women because of his four older sisters always giving him a hard time, fanfics usually write him as being gay, even if they're not yaoi fics. Not helped by Creator/YuuWatase giving a WordOfGay in regards to him. [[TeasingCreator LOL]].