Character derailment

Character derailment is the opposite of mh:greatcharacters:character development. Instead of learning from mistakes, characters just get worse.

It is not to be confused with flanderization, as Flanderization involves over-exaggerating and amplifying a character's traits to the point that it goes too far. Character derailment, on the other hand, refers to a character's traits (flanderized or not) becoming vastly different compared to what was previously shown.

Why This Trope Sucks

 * 1) Alongside the negative aspects of Flanderization, this makes characters we once liked, loved, and/or adored and makes them become a lot more unlikeable or hard to tolerate than how they started off.
 * 2) This trope often makes the character become poorly written on top of being unlikable due to having the lack of balance between their flaws and what makes them redeemable/likable.
 * 3) Changing up the personalities of what made the character(s) originally used to be in an improper fashion tends to be executed badly by making them too out-of-character for their own good.

Redeeming Qualities

 * 1) When characters are given proper character development, it makes them sympathetic and likable.
 * 2) There are many instances when changing up the personalities of a character can be done in good light. Where it can potentially make them more entertaining to watch, this is better shown in the good aspects of flanderizing a character. The category Category:Dynamic characters on GCW can be potentially considered to be the good side of both; Flanderization and this trope to an extent.
 * 3) * Three examples of these include Homer Simpson from The Simpsons during Seasons 1 to 10; where he was originally a brash, good-hearted father who was a little clumsy as of Season 3 and Season 4-7 has made him into a more of a well-written dingbat that made him more hilarious, lovable and entertaining than before, Hugh Neutron from The Adventures of Jimmy Neutron; in the original movie, he was intelligent if a goofy father and the show has made him more of a lovably weird manchild whose also idiotic and hilarious in a well-written fashion, and finally, mh:greatcharacters:Earthworm Jim from the animated series with the same name; in the original games, he was a goofy yet diligent hero who is prone to the game's comedic moments despite being competent, the animated series made him more of an incompetent and childish goofball with a hammy dialect who's also enjoyably spunky, boisterous, talented, heroic and unpredictable.
 * 4) There are viewers who can still enjoy these characters and find them entertaining despite their derailment.

Notable Characters Who Suffered Character Derailment

 * Fonzie (Happy Days; Season 4-11; He is the trope namer for jumping the shark, which he literally did in the episode Hollywood Part 3. This is character derailment because in Season 2 he got hurt)
 * Skarloey (Thomas and Friends):During seasons 8-12, he acts like a child. Thankfully in the Movie "Blue Mountain Mystery", he is back portrayed as an old grandpa.
 * SwaySway and Buhdeuce (Breadwinners; as the series went on, they began to treat each other like crap, especially in "Wolf Head Bread" and "Unlucky Duckies")
 * The Titans (Teen Titans Go!)
 * The Powerpuff Girls (The Powerpuff Girls 2016)
 * Henry Hart/Kid Danger (Henry Danger)
 * Ray Manchester/Captain Man (Henry Danger)
 * Charlotte Page (Henry Danger)
 * Jasper Dunlop (Henry Danger)
 * Piper Hart (Henry Danger)
 * Danger Mouse (2015) (mh:besttvshows:Danger Mouse (2015))
 * Sasuke Uchiha (Naruto Shippuden)
 * Madara Uchiha (Naruto)
 * Yuuki Terumi (BlazBlue series)
 * Nana (Elfen Lied)
 * Son Goku (Manga only)
 * Dongtae (DICE: The Dice That Changes Everything; season 4)
 * Aya Asagiri (Magical Girl Site; second half-became a muted girl after Yatsumura lost her lifespan and vanished)
 * The Thunderman Family (The Thundermans)
 * Thomas the Tank Engine (Seasons 12-16)
 * Dawn Harper (Nicky, Ricky, Dicky, & Dawn)
 * Daffy Duck (Looney Tunes; DePatie Freleng/Seven-Arts Era)
 * Spongebob Squarepants (SpongeBob SquarePants: Seasons 6 & 7)
 * Patrick Star (Spongebob Squarepants; Seasons 6-8)
 * Mr. Krabs (Spongebob Squarepants)
 * Cosmo Cosma (The Fairly OddParents; Season 9 & 10)
 * Blooregard Q. Kazzo (Foster’s Home for Imaginary Friends; Seasons 2-6)
 * Carl Wheezer (The Adventures of Jimmy Neutron: Boy Genius; He had shades of this in Season 3 but was still a decent character despite this)
 * Hugh Neutron (The Adventures of Jimmy Neutron: Boy Genius; He is much less intelligent in the TV show than in the movie.)
 * Sheen Estevez (Planet Sheen)
 * Seymour Skinner (The Simpsons; Seasons 9-30)
 * Homer Simpson (The Simpsons; Seasons 11-30)
 * Marge Simpson (The Simpsons; Seasons 16-30)
 * Bart Simpson (The Simpsons; Seasons 16-30)
 * Lisa Simpson (The Simpsons; Seasons 7-30)
 * Ned Flanders (The Simpsons; Seasons 11-31)
 * Peter Griffin (Family Guy; Season 8-present)
 * Lois Griffin (Family Guy; Season 8-present)
 * Brian Griffin (Family Guy; season 8-present)
 * Rosalina (SuperMarioLogan)
 * Mr. Goodman (SuperMarioLogan 2016-present)
 * Discord (My Little Pony: Friendship is Magic; Season 9-He had a chance of becoming a good guy, until it was revealed that he was Grogar all along. He then put the whole world in danger as he made the terrible trio so powerful that even he couldn't deal with them, which just goes against his whole development)
 * Stella (Winx Club; Seasons 5-9; Her childishness got much worse, with her throwing actual tantrums over not getting her way.
 * Diaspro (Winx Club; Seasons 3-9; Was derailed into a Miss Jerkass Yandere who eagerly brainwashed Sky in order to marry him and tried to kill Bloom. She was also made a Karma Houdini because she wasn't punished for what she had done at Domino.
 * Tecna (Winx Club; Seasons 5-9; She went back to acting like her season 1 self, thus losing a lot of the development she got in seasons 1-4. She still had several good moments in the later seasons though)
 * Chloe Bourgeois (Miraculous Ladybug; Season 3-present)
 * Eddy (Ed, Edd, n Eddy; Season 5-6)
 * Ed (Ed, Edd, n Eddy; Seasons 5-6)
 * Sarah (Ed, Edd, n Eddy; Seasons 5-6)
 * Jimmy (Ed, Edd, n Eddy; Seasons 5-6)
 * Kevin (Ed, Edd, n Eddy; Seasons 5-6)
 * Rolf (Ed, Edd, n Eddy; Seasons 5-6)
 * Johnny 2x4 (Ed, Edd, n Eddy; Seasons 5-6)
 * Lee Kanker (Ed, Edd, n Eddy; Seasons 5-6)
 * Marie Kanker (Ed, Edd, n Eddy; Seasons 5-6)
 * Numbah Four (Codename: Kids Next Door)
 * Hot Shot (Transformers: Cybertron)
 * Gumball Watterson (The Amazing World of Gumball; Seasons 2, 5-present; He is an even bigger jerk in Season 2, and his jerkish behavior is toned down in the recent episodes)
 * Danny Fenton/Phantom (Danny Phantom; Season 3)
 * Inferno/Roadblock (Transformers Energon Season 3?)
 * Bumblebee (Transformers: Robots in Disguise 2015)
 * Ellie (The Last of Us Part II)
 * Lynn Loud Jr (The Loud House)
 * Light Yagami (Death Note)
 * Suzaku Kururugi (Code Geass)
 * Nino Arizugawa (Anonymous Noise; Had been forming a relationship with Yuzu (even being kissed by him very often), only for her to turn him down and go back together with Momo.)
 * Sindel (Mortal Kombat 11)
 * Waldek Kiepski (Świat Według Kiepskich)
 * Jin Kazama (Tekken 6)
 * All of the main characters (Game Shakers)
 * Johnny Test (Johnny Test 2005; usually seen as selfish, disrespectful, immature, gross, and narcissistic. While he was slightly tolerable in the first season, he got flanderized by the second season and started to mess up his sisters' inventions for his own self-serving purposes, which resulted in him causing trouble for himself and the whole city.)
 * Lincoln Loud (The Loud House; Season 4-present; he did very stupid and selfish things he has done.)
 * Gelatin (Battle for BFDI; While he has always been impulsive to some extent, this is cranked up to 10 in this season where he makes mistakes and act reckless even more often.)
 * Four (Battle For BFDI; Almost to the highest degree possible. He was once a caring number in XFOHV and 9 years later became a selfish, sociopathic jerk who abuses nearly everyone and everything around thing.)
 * Memetchi (Tamagotchi! Season 1B)
 * Bob (SMG4; 2018; In the 2018 era of SMG4, Bob has became more mean-spirited and jerkish towards his friends, and while he wasn’t a saint during 2016, 2017, and 2019-present, he was never this selfish either.)
 * Fishy Boopkins (SMG4; 2017-present)
 * Bowser (SMG4; 2018-present; He started to go from a villain like his original counterpart, to a friendly hero who is friends with Mario, SMG4, and the gang and rarely kidnaps Peach. In 2019, he began to suffer from being demoted to a recurring/minor/background character like all the other old characters whether they are Mario characters or not who are not Mario, SMG4, Luigi, Fishy Boopkins, Bob, Chris and Swagmaster, SMG3, or Meggy and Shroomy to lesser extents presumably due to the popularity and shoehorning of the OC characters like Tari, Saiko, Axol, and Melony.)
 * Bella Swan (Twilight)
 * Any character from Sunny Bunnies (Season 4-present)
 * NostalgiaSquare (NostalgiaSquare; 2018)
 * Green Square (NostalgiaSquare; While he was already annoying on NostalgiaSquare's TikTok account, offbrand_square, he became worse when NostalgiaSquare introduced his TikTok creation to Scratch, where he became a selfish, obnoxious, and arrogant jerk to the point where almost all of his redeeming qualities have went away from him and also to the point where he never shuts up about how "awesome" he is.)
 * Courtney (Total Drama)
 * Mike (Total Drama All-Stars)
 * Zoey (Total Drama All-Stars)
 * Duncan (Total Drama)
 * Sky (Total Drama Pahkitew Island)
 * Dave (Total Drama Pahkitew Island)
 * Gwen (Total Drama)
 * Jaden Yuki (Yu-Gi-Oh! GX, Season 4; he suffered from massive PTSD in the arc as he became very brooding and cynical and lost his enjoyment in having fun in dueling)
 * Sonic the Hedgehog (Sonic the Hedgehog, 2006)
 * Jet the Hawk (Sonic Free Riders)
 * Earthworm Jim (Earthworm Jim TV series)
 * Mushu (Mulan 2)
 * Blinky, Clyde and Pinky (Pacman 1982 TV series; Blinky and Clyde swapped personalities, as the former became the coward with lack of self-esteem and the latter the grumpy determined leader and Pinky went from a cunning female to a male "more brawns than brains" ghost)
 * Lord Betrayus (Pac-Man and the Ghostly Adventures; as discussed on the show's page on TTSW and Betrayus's own page, he started off as a passable comic-relief villain in the very first episode "The Adventure Begins" Part 1 to 2; who also had a somewhat sympathetic backstory for being banished and his motive to get his body back to conquer Pac-World, but over time, he was treated more like an annoying comic-relief nuisance than a threatening villain)
 * Mizuki Himeji (Baka and Test: Summon the Beasts; In the first season, she started off as a nice, sweet and helpful girl who's good friends with Minami, Yuuji, Hideyoshi and Kouta, and is willing to help Akihisa out when she needs to with a couple of yandere-ish moments here and there, though it was mostly used as a one-off gag and nothing too serious. In the OVA, she became a mild yandere but not too bad. And then comes the second season where she was reduced to a yandere who does nothing but torture Akihisa as she and Minami make Akihisa's life a living hell.)