History Main / AdaptationDrift

* ''Manga/BlackButler'' plays with this. Only the first 9 episodes are adapted from the manga. The rest of the first and second seasons opt to tell their own story. However the third season ''Book of Circus'', OVA ''Book of Murder'' and ''Book of Atlantic'' are connected arcs taken from the manga, essentially mid-sequels taking place before the anime diverges.

* The 2001 ''Manga/ShamanKing'' anime for the most part stays faithful to the manga right up until the defeat of Tao En, after which it almost entirely diverges from the manga with only certain tertiary events being adapted. These include completely changing Hao's entire character to make him more overtly evil and a GeckoEnding where Yoh actually defeats him as opposed to Hao winning the Shaman Tournament. This was due to dwindling sales and the manga being published at a slow rate.

* ''Fanfic/TheLoudHouseRevamped'' started as a standard self-insert ''WesternAnimation/TheLoudHouse'' fanfiction before turning into a massive crossover with a huge cast ensemble and strict formula: Team Loud Phoenix Storm saves several girls who join Lincoln's harem.

* The TV series ''Series/{{Hannibal}}'' was originally presented as a prequel to the books, set prior to Hannibal being caught and put in prison. However, over the course of three seasons the story and character relationships developed to the point where it was outright incompatible with the canonical beginning of the books. Although the later seasons mix-and-matched storylines from the books, by the end of the show it was by explicitly set in an AlternateContinuity.

* ''Series/ThirteenReasonsWhy'': The first season is largely faithful to [[Literature/ThirteenReasonsWhy the book]], albeit with a lot of AdaptationExpansion due to the difference in medium. From the second season onwards, it delves into completely original territory (although some plotlines build off what occurred in Season 1) and even adds new information or retcons to the more book-faithful elements (for example, Zach and Hannah are acquaintances in Season 1 and Zach has a crush on her, which is how they're presented in the book; Season 2 deviates from this to reveal [[spoiler:they were exes]].

* ''Manga/RurouniKenshin'': While the 1996 show had some fillers early on, it remained faithful to the manga until the Kyoto arc. After that, the show diverges with its own original stories starting with the Shimabara arc and it ended with the Feng Shui arc.
* The 2001 ''Manga/ShamanKing'' anime for the most part stays faithful to the manga right up until the defeat of Tao En. After which it almost entirely diverges from the manga with only certain tertiary events being adapted. This includes completely changing Hao's entire character to make him more overtly evil and a GeckoEnding where Yoh actually defeats him as opposed to Hao winning the Shaman Tournament. This was due to dwindling sales and the manga being published at a slow rate.

* ''Manga/FullmetalAlchemist'' has two anime adaptions: ''Fullmetal Alchemist: Brotherhood'' and ''Anime/FullmetalAlchemist2003''. ''Brotherhood'' is a TruerToTheText that started when the manga was already almost finished. The other anime run 2003 to 2004 and eventually OvertookTheManga, therefore its plot diverges around halfway through the series.

** After five of the first six films were largely faithful adaptations of their respective novels (''Film/YouOnlyLiveTwice'' being the exception), the films became original stories that borrowed names, locations, and incidents from their namesake novels. The results range from InNameOnly (''Film/TheSpyWhoLovedMe'' famously because Creator/IanFleming disliked the book, but [[Film/TheManWithTheGoldenGun its predecessor]] and [[Film/{{Moonraker}} successor]] are just as unregonizable) to loose adaptations (e.g., ''Film/ForYourEyesOnly'' is its namesake story + "Risico" + an original MacGuffin plot, with a bit from ''Literature/LiveAndLetDie'' thrown in). By the Creator/PierceBrosnan era, borrowing from Fleming stopped.

** The Creator/DanielCraig reboot films started with a SettingUpdate of ''Literature/CasinoRoyale'' with the reason for the villain's situation changed and presented as the first act rather than an ExpositionDump. ''Film/QuantumOfSolace'' borrowed one of the remaining unused Fleming names (but had nothing else to do with the namesake story) and included a finale inspired by one of the other Bond stories ("007 in New York"). After that, it was back to original stories.

* ''Series/ScreamTVSeries'': {{Inverted}}. The first two seasons follow the basic premise of the film series but largely do their own thing. The third season is a reboot that borrows more elements from the film series, even featuring the return of both Creator/RogerLJackson and the classic Scream mask, which were replaced by a new voice actor and mask.

* ''Anime/HyperdimensionNeptuniaTheAnimation'' adapts a few plot points from ''[[VideoGame/HyperdimensionNeptuniaMk2 mk2]]'' for the first half of episodes and ''[[VideoGame/HyperdimensionNeptuniaVictory Victory]]'' for the second half. And while it does [[PragmaticAdaptation change a few elements from those two games]] for the sake of the adaptation, as well as being an AlternateContinuity from the start, the anime mostly stays true to the games it's adapting from. But starting from the 13th episode, the anime began to distance themselves from the games by having an entirely original story. This would continued further with the three [=OVAs=] (''Neptune's Summer Vacation'', ''Nep-Nep Festival'', and ''Little Purple Sunshine''), as while it does take a few elements from ''[[VideoGame/MegadimensionNeptuniaVII VII]]'' (such as Adult Neptune saving the other Candidates from a monster attack [[spoiler:and a brief cameo from Uzume at the end of the 4th OVA]]), the anime had already became its own thing, even including elements exclusive to the anime like the Purple Heart's Lilac COOL Processor in the 2nd OVA and Adult Neptune's Gen. Unit Processor in the 3rd OVA, which itself [[RetCanon would eventually be included]] in the games proper within it's spin-off titles: ''Dimension Tripper Neptune: TOP NEP'' (which was [[RecursiveAdaptation based on the anime]]) and ''VideoGame/NeptuniaGameMakerREvolution'' (where it would be officially canonized).

* ''Anime/HyperdimensionNeptuniaTheAnimation'' adapts a few plot points from ''[[VideoGame/HyperdimensionNeptuniaMk2 mk2]]'' for the first half of episodes and ''[[VideoGame/HyperdimensionNeptuniaVictory Victory]]'' for the second half. And while it does [[PragmaticAdaptation change a few elements from those two games]] for the sake of the adaptation, as well as being an AlternateContinuity from the start, the anime mostly stays true to the games it's adapting from. But starting from the 13th episode, the anime began to distance themselves from the games by having an entirely original story. This would continued further with the three [=OVAs=] (''Neptune's Summer Vacation'', ''Nep-Nep Festival'', and ''Little Purple Sunshine''), as while it does take a few elements from ''[[VideoGame/MegadimensionNeptuniaVII VII]]'' (such as Adult Neptune saving the other Candidates from a monster attack [[spoiler:and a brief cameo from Uzume at the end of the 4th OVA]]), the anime had already became its own thing, even including elements exclusive to the anime like the Purple Heart's Lilac COOL Processor in the 2nd OVA and Adult Neptune's Gen. Unit Processor in the 3rd OVA, which itself [[RetCanon would eventually be included]] in the games proper within it's spin-off titles: ''Dimension Tripper Neptune: TOP NEP'' (which was [[RecursiveAdaptation based on the anime]]) and ''VideoGame/HyperdimensionNeptuniaGameMakerREvolution'' (where it would be officially canonized).

* ''Series/GameOfThrones'': The first couple of seasons were near-identical to the books, but incremental changes accumulated over time -- by season 5, several characters were on a different storyline altogether, or just didn't exist (such as the Lady Stoneheart and Young Griff), before the series OvertookTheManga altogether and had to write its own ending.

* ''Anime/NeonGenesisEvangelion'': The ''Anime/RebuildOfEvangelion'' film saga consists of four films that start off retelling the events of the original 1995 TV show. The first film is a CompressedAdaptation of the first six episodes, though there are some changes that make it an actionized retelling. By the time of the second film however, things start diverging very fast that it goes OffTheRails from the original that it establishes an AlternateContinuity. It introduces a new character known as Mari Makinami Illustrious, [[spoiler:has Shinji Ikari almost bring the end of the world]], with the consequences explored in the third and fourth films with completely new material not present from the source.

* ''Anime/HyperdimensionNeptuniaTheAnimation'' adapts a few plot points from ''[[VideoGame/HyperdimensionNeptuniaMk2 mk2]]'' for the first half of episodes and ''[[VideoGame/HyperdimensionNeptuniaVictory Victory]]'' for the second half. And while it does [[PragmaticAdaptation change a few elements from those two games]] for the sake of the adaptation, as well as being an AlternateContinuity from the start, the anime mostly stays true to the games it's adapting from. But starting from the 13th episode, the anime began to distance themselves from the games by having an entirely original story. This would continued further with the three [=OVAs=] (''Neptune's Summer Vacation'', ''Nep-Nep Festival'', and ''Little Purple Sunshine''), as while it does take a few elements from ''[[VideoGame/MegadimensionNeptuniaVII VII]]'' (such as Adult Neptune saving the other Candidates from a monster attack [[spoiler:and a brief cameo from Uzume at the end of the 4th OVA]]), the anime had already became its own thing, even including elements exclusive to the anime like the Purple Heart's Lilac COOL Processor in the 2nd OVA and Adult Neptune's Gen. Unit Processor in the 3rd OVA, which itself [[RetCanon would eventually be included]] in the games proper within the spin-off titles: ''Dimension Tripper Neptune: TOP NEP'' (which was [[RecursiveAdaptation based on the anime]]) and ''[=GameMaker=] R:Evolution'' (where it would be officially canonized).

* ''Anime/LoveLiveNijigasakiHighSchoolIdolClub'' doesn't have much in common with its source material, ''VideoGame/LoveLiveSchoolIdolFestivalALLSTARS'', to begin with, but as far as Season 1 goes the anime at least adheres to some of the plot beats from the game despite drastically altering the context surrounding them. Come Season 2, however, and the plot completely diverges from the video game; Lanzhu and Mia are in it, and subunits are introduced, but aside from that everything in the anime's Season 2 is completely original.
* ''Anime/NeonGenesisEvangelion'': The ''Anime/RebuildOfEvangelion'' film saga consists of four films that start off retelling the events of the original 1995 TV show. The first film is a CompressedAdaptation of the first six episodes, though there are some changes that make it an actionized retelling. By the time of the second film however, things start diverging very fast that it goes OffTheRails from the original that it establishes an AlternateContinuity. It introduces a new character known as Mari Makinami Illustrious, [[spoiler:has Shinji Ikari almost bring the end of the world]], with the consequences explored in the third and fourth films with completely new material not present from the source.
* ''Manga/ThePromisedNeverland'' was originally a manga with twenty volumes. When adapted as an anime, the first season was a faithful adaptation of the first arc. However, with the rest of the work being adapted into a single season, the anime took many creative liberties to condense the material.
* The 2001 ''Manga/ShamanKing'' anime for the most part stays faithful to the manga right up until the defeat of Tao En. After which it almost entirely diverges from the manga with only certain tertiary events being adapted. This includes completely changing Hao's entire character to make him more overtly evil and a GeckoEnding where Yoh actually defeats him as opposed to Hao winning the Shaman Tournament. This was due to dwindling sales and the manga being published at a slow rate.
* ''Manga/BlackButler'' plays with this. Only the first 9 episodes are adapted from the manga. The rest of the first and second seasons opt to tell their own story. However the third season ''Book of Circus'', OVA ''Book of Murder'' and ''Book of Atlantic'' are connected arcs taken from the manga, essentially mid-sequels taking place before the anime diverges.

* ''Manga/RurouniKenshin'': While the 1996 show had some fillers early on, it remained faithful to the manga until the Kyoto arc. After that, the show diverges with its own original stories starting with the Shimabara arc and it ended with the Feng Shui arc.

* ''Manga/TsubasaReservoirChronicle'': Season 1 follows the manga storyline very closely but it's only in Season 2 that the show diverges from the manga starting with the Rekord arc where instead of following it up with the Acid Tokyo arc, it went with an anime original storyline. At that point, more anime original stories show up, and Season 2 ended with the characters saying AndTheAdventuresContinues. The two [=OVAs=] released after the show adapted the Acid Tokyo and Nihon arcs ignoring the show's original storylines but they skipped the Celes arc.

[[folder:Web Animation]]

* ''WebVideo/ScootertrixTheAbridged'' starts off as an AbridgedSeries of ''WesternAnimation/MyLittlePonyFriendshipIsMagic'', with the first three episodes sticking closely to the plot from each corresponding episode of the original show. But subsequent episodes introduce completely different plots from the original show, villains from later seasons [[AdaptationalEarlyAppearance show up in the middle of season one]], and the series develops an overarching plot about Equestria going to war. The series creators started frankensteining footage from different episodes (and even commissioned completely original animations) to tell the story they wanted--to the extent that ''Scootertrix'''s original final episode doesn't include any footage or plot details from the corresponding ''Friendship Is Magic'' episode. The followup series, ''Scootertrix the Epilogue'', uses completely original animation and doesn't even pretend to be an abridged series anymore.

* ''Franchise/StarWars'' had this happen between the original trilogy, the prequels, and the shows quite a bit.
** A few details had been firmly established in the originals: Uncle Owen was (likely) Anakin's brother, Obi-Wan's clothing on Tatooine was just to protect from the elements, and Luke and Leia's mother died when Leia was "very young," implying Leia was about three or four when it happened.
** Then came the prequels, which turned scant details into an AdaptationExpansion. Unfortunately, it also led to a few plot holes getting punched in the original details. Obi-Wan's clothing became the wardrobe the entire Jedi Order used, which made it hard to take seriously him hiding out on Tatooine in plain sight when he was the equivalent of a cop wearing his dress blues all the time. Anakin was explicitly established as an only child, making a convoluted set of events fall into place so Owen could still be his ''stepbrother.'' Padme, Anakin's wife, dies in childbirth, meaning the only way Leia could have known her was if she had some kind of superbaby memory that went back to the very moment of her birth.
** The shows such as ''The Clone Wars'' and ''Rebels'', kept piling on more details that contradicted the already established movies. Anakin was shown to have an apprentice in the form of Ahsoka who never appeared in the prequels, turning it into a case of RememberTheNewGuy. Ahsoka, a character that was explicitly said could have redeemed Darth Vader by her creator Dave Filoni, is PutOnABus in Rebels so as not to interfere with Luke being the one to redeem his father. Likewise, several other Jedi characters are established to have survived Order 66 in tie-in materials, despite Obi-Wan stating the Jedi are extinct save for him and Yoda by the time of the original trilogy.

Little details can add up-- when the adaption decides to [[DeathByAdaptation kill off]] one minor mauve-shirt [[SparedByTheAdaptation instead of the other]], it may seem not have much effect on that episode, but what happens when that minor character gets promoted to a main protagonist later in the source material? Do they bring the original BackFromTheDead, or give the role to another character? Or should that storyline be dropped altogether, risking even more deviation down the line.

* ''Series/BeingHumanUS'': The [=SyFy=] remake's first season was largely a close adaptation of [[Series/BeingHumanUK the original UK series]]' first season, with similar story and character arcs and progressions of events -- the US series premiere in particular had a near-identical synopsis and some ''shot-for-shot'' scene recreations from the UK series' premiere. Season 2 however had almost nothing in common story-wise with the UK show's second season beyond picking up the first season's UK-paralleling plot threads, and Season 3 finally firmly established the US series as a narratively completely-separate show from the UK series.
* ''Series/{{Clarice}}'' starts off as a sequel series to ''Film/SilenceOfTheLambs'' before making sharp diversions from the source material - most notably its strong implications that Clarice and her friend/roommate Ardelia are more than friends, and revealing that Clarice's father was a CorruptCop.

* ''Series/GameOfThrones'': The first couple of seasons were near-identical to the books, but incremental changes accumulated over time-- by season 5, several characters were on a different storyline altogether, or just didn't exist (such as the Lady Stoneheart and Young Griff), before the series OvertookTheManga altogether and had to write its own ending.

* The Netflix version of '' Series/TheUmbrellaAcademy'' was never extremely close to the comic books, as it incorporated several {{Actor Inspired Element}}s as well as AdaptationalDiversity. However, the first season roughly follows the plot of the first book, while later on these changes snowball into an entirely different plot for many characters-- for example, Victor's gender identity arc, and Allison's storyline being about racism when she was white in the comics.

* The 2001 Manga/ShamanKing anime for the most part stays faithful to the manga right up until the defeat of Tao En. After which it almost entirely diverges from the manga with only certain tertiary events being adapted. This includes completely changing Hao's entire character to make him more overtly evil and a GeckoEnding where Yoh actually defeats him as opposed to Hao winning the Shaman Tournament. This was due to dwindling sales and the manga being published at a slow rate.

* The 2001 Manga/ShamanKing anime for the most part stays faithful to the manga right up until the defeat of Tao En. After which it almost entirely diverges from the manga with only certain tertiary events being adapted. This includes completely changing Hao's entire character to make him more overtly evil and a GeckoEnding where Yoh actually defeats him as opposed to him winning the Shaman Tournament.

!! Examples

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* ''Series/You2018'': The 3rd book in the series was released before the 3rd season was released, but after development had already started. Thus, season 3 does its own thing.