History Main / EvilFormerFriend

** Toa Nidhiki, not that you'd know it by his current insectoid appearance. He tried to sell out the Toa to the Dark Hunters in return for being put in charge of the conquered city, but Lhikan overheard him making the plans and set a trap of his own, and forced Nidhiki to leave with the defeated Hunters. When he tried to betray ''them'', The Shadowed One hired [[FemmeFatale Roodaka]] to use her powers to transform him into his current state ([[AndIMustScream the irony being that]] [[IronicHell he's]] ''[[IronicHell terrified]]'' [[IronicHell of insects]]).
--->'''Nidhiki''': "''This time, your farewell will be forever, '''brother.'''''"
--->'''Lhikan''': "''You lost the right to call me brother'' '''''long ago!'''''"

* In ''WesternAnimation/TheLegendOfKorra'' Book 3, Suyin's right hand man [[spoiler: Aiwei turns out to have been a traitor secretly working to hand over Korra to the Red Lotus]].
** In Book 4, Su's ward and mentee [[Characters/TheLegendOfKorraKuvira Kuvira]] goes mad with power in her quest to re-stabilize the Earth Kingdom, [[spoiler: even throwing Su and the rest of the Zaofu Beifong family in prison and attempting to sacrifice Su's eldest son Baatar when the latter is no longer useful for her plans]]. Su just cannot catch a break with this.

* Characters/DoctorDoom is presented as former friend of the ComicBook/FantasticFour in most live-action film incarnations like ''Film/FantasticFour2005'' and ''Film/FantasticFour2015''.

** ''WesternAnimation/TheBatman'' gives us Ethan Bennett, both a high-school friend of Bruce Wayne's and one of the only cops willing to give Batman a chance. [[spoiler:Naturally, he's accidentally turned into Clayface in the Season 1 finale. He eventually becomes a good guy again after spending a while in the HeelFaceRevolvingDoor.]]

* Penny to Bessie from ''WesternAnimation/TheMightyB''. She also conbined this with TheEeyore and WoobieDestroyerOfWorlds tropes.

** In Book 4, Su's ward and mentee Kuvira goes mad with power in her quest to re-stabilize the Earth Kingdom, [[spoiler: even throwing Su and the rest of the Zaofu Beifong family in prison and attempting to sacrifice Su's eldest son Baatar when the latter is no longer useful for her plans]]. Su just cannot catch a break with this.

* [[CainAndAbel Nightmare Moon to Princess Celestia]] in ''WesternAnimation/MyLittlePonyFriendshipIsMagic''. Prior to her FaceHeelTurn, she was Princess Luna, a co-ruler of Equestria alongside her sister. [[spoiler:They eventually patch things up once Luna is purged of her SuperpoweredEvilSide and its influence.]]

* The usual dynamic is flipped in ''WesternAnimation/SheRaAndThePrincessesOfPower'', as the series begins with best friends and [[LesYay bunkmates]] Adora and Catra being soldiers for the Horde. Adora later [[HeelFaceTurn throws in her lot]] with the Princess Rebellion [[ObliviouslyEvil after realizing what the Horde actually does]]. Catra, having always been aware of their villain status, had hoped that the duo could eventually climb the ranks of command in hopes of [[TheStarscream being in charge themselves]]; when Adora leaves, she sticks to this plan and quickly becomes TheDragon.

** ''Westernanimation/KungFuPanda'': Shifu found Tai Lung as a cub and raised him like a son. Shifu trained him and promised him that he was destined for greatness, which lead to Tai Lung desiring the Dragon Scroll. Unfortunately, Oogway, sensing the darkenss within Tai's heart, told them that he didn't deserve the scroll, leading to an embittered Tai Lung attacked the village in rage. This ended up forcing Shifu to stop him and send him to prison.

* The three executives of the [[NebulousEvilOrganisation Armed Brain Army Volt]] were once university classmates of the ''Series/ChoujuuSentaiLiveman'' until they let their ego and ambitions get the better of them and left to join an evil geniocratic {{cult}}.

* In the fanfic novelization ''Fanfic/BreathOfTheWild'', a female Yiga Footsoldier ambushed Link in his own home. He [[CurbStompBattle curb stomps]] her, and sends her flying out of his house. As she lay dying, the woman gives him a ReasonYouSuckSpeech, saying he's no different than the Yiga with how brutal he was towards them during the hideout invasion. He already has freed Ruta and Naboris by this point, so he uses Mipha's Grace to heal the woman, and gives her a ShutUpHannibal speech before killing her outright. Paya reveals to Link that she recognized the woman's voice as her old friend Melonie, a girl she grew up with who just vanished. Paya was devastated to learn that Melonie had turned to the Yiga.

[[caption-width-right:350:Once an [[WesternAnimation/MonstersUniversity cuddly college campusmate]], now an [[WesternAnimation/MonstersInc odious office opponent]].]]

[[caption-width-right:350:Once an cuddly college campusmate, now an odious office opponent.]]

[[caption-width-right:350:Once an cuddly college campusmate, now an odious office opponent.]]]]

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* In ''ComicBook/ConanTheBarbarian'' Thoth Amon is revealed to have been Kalanthes's best friend at one point before he turned to Set worship and destroyed everything Kalanthes holds dear. Even before that was revealed there were hints that their hatred went deeper than religious differences.

* In ''Franchise/TheFlash'':

* Sinestro to Hal Jordan in ''Franchise/GreenLantern''. He was once Jordan's mentor and a close friend before he went JumpingOffTheSlipperySlope. Hal is still bitter and remorseful about it, while Sinestro [[BigBadFriend still sees Hal as a friend]] and deeply respects him, even if they're now on opposing sides.
* Lady Shiva was once a good friend of ComicBook/RichardDragon and Bronze Tiger before her BloodKnight tendencies, ambition and her sister's death turned her already morally questionable search for a WorthyOpponent into her entire raison d'etre. When she runs into the two of them these days she still talks like a friend, while trying to force them into a one on one fight to the death. This includes kidnapping Dragon and being entirely unconcerned when Tiger is nearly killed in one of her plots.

** At first played straight but then subverted with the ComicBook/{{New 52}} version of ComicBook/{{Cheetah}}. Franchise/WonderWoman tells the JLA that Barbara Minerva was her first true friend in Man's World, a scholar who helped Diana on various quests for mystical artifacts. Studying a dagger, Barbara was cut by it and transformed into the Cheetah. She and Diana fought numerous times, with Diana trying to help her friend and considering her a victim. However, meeting the cult who created the dagger, Wonder Woman learns that the Cheetah is meant to be a protecting spirit but the inner darkness within Barbara turned it into a beast. Batman then reveals that "Barbara Minerva" was the alias of a long-time thief, con artist and attempted murderer and Diana is rocked to realize that Barbara was never an innocent or her friend.

** The retconns imposed by ''ComicBook/DCRebirth'' which did away with the drastically DarkerAndEdgier tone of the New 52's Wonder Woman ensured that in ''ComicBook/WonderWomanRebirth'' Barbara's friendship was genuine and it therefore plays the trope straight, and uses it to put Barbara and the reader's emotions through the wringer.

* ''Franchise/XMen'':

** ComicBook/{{Wolverine}} and ComicBook/{{Sabretooth}}. ''First X-Men'' actually shows us why the two went their separate ways. After forming a group of mutant rebels to fight the government, Victor wants to take off with his love interest and leave the fighting to someone else. However, Wolverine, by that point, had already convinced everyone that what they were doing was necessary, so she stayed. She is killed in the final conflict, but instead shows Victor a vision of her getting better, and the two having a family and living a happy life, before cutting the illusion and telling Creed ''that'' is what he should remember, and that it doesn't have to mean anything less. Creed took this to heart, blaming Logan for taking away his happy ending, and told Logan that he would ensure that he never find anything or anyone worth living for.

* In Myth/NorseMythology, Odin and Loki were once [[BloodBrothers sworn brothers]].

* ''WesternAnimation/TheEmperorsNewGroove'': When Kuzco fires Yzma, his closest advisor, [[spoiler: she plots to murder him as revenge]].

** Tobi has been revealed to be Obito Uchiha, Kakashi's best friend and role model. The pain of this revelation left Kakashi reeling in shock long enough to nearly be killed.

* ''Manga/JujutsuKaisen'': Back when they were both students of Jujutsu High, Satoru Gojo and Suguru Geto were close friends, being the strongest sorcerers of their generation and often working together on missions. [[spoiler: A combination of Gojo outpacing him (leaving Geto feeling increasingly isolated), trauma over Riko Amani's death, and the realization that [[TheHeartless Curses]] would no longer exist if all non-sorcerers died leads to Geto snapping and descending into [[FantasticRacism full-on hatred for non-sorcerers]], deciding to kill all humans except for sorcerers, something Gojo (Who came out of the incident with the opposite moral, namely that sorcerers exist to protect non-sorcerers) heavily opposed. For added bitterness, the end of the movie heavily implies that the two still considered each other dear friends even after Geto's FaceHeelTurn, with Gojo calling him his one and only friend after the latter dies.]]