->''"Have you been keeping well? Thank you for Mt. Coronet. I'm truly grateful. [...] The power you learned... I can feel it emanating from you. But that's enough talk. Let's get on with why you're here. As the Pokémon League Champion, I accept your challenge! There won't be any letup from me!"''
-->-- '''[[FinalBoss Champion]] [[BigGood Cynthia]]''', ''VideoGame/PokemonDiamondAndPearl''

A BossBattle in which you fight against a character who's explicitly on your side (otherwise it's CivilWarcraft or LetsYouAndHimFight). Occasionally this is the WarmupBoss in which your ally decides to test your skills before you start your real mission. It can also be a form of HeroicSacrifice in which the other good guy must die in order to accomplish a goal, and you have to be the one to do it. In some cases, your ally or allies are being [[BrainwashedAndCrazy mind-controlled]] or otherwise forced to fight you. Or maybe they have done a FaceHeelTurn and have become evil. Occasionally, especially in {{Fighting Game}}s, a character will beat up their friend to prevent them from fighting the BigBad. Better a few lumps than getting killed. In the end, most of the time, the real reason it happens is for the [[RuleOfCool cool fight that couldn't happen otherwise]].

There are a few situations in which this may become a case of ThatOneBoss. An ally may be [[WithGreatPowerComesGreatInsanity powered by the dark side]] or [[DuelBoss has to be fought one-on-one]] with either a specific character or the player character. In western [=RPG=]s about building individual character strength, no problem...you should be a GameBreaker by this point anyways. But in a Japanese RPG that emphasizes the strength of a group working together? Having only one ally might be ''quite'' a handicap without additional damage-dealers and tanks. Sure, in this case, the opponent may have reduced stats compared to a regular boss fight, but still almost always [[TheComputerIsACheatingBastard way more stats than they could ever actually attain while on your side]] to give the player a challenge. They'll also have their entire skillsets to throw at you, occasionally [[SecretAIMoves even more]].

It may overlap with DuelingPlayerCharacters. Contrast DefeatMeansFriendship, in which case a villain becomes your ally because you fought it. Compare TragicMonster, IKnowYoureInThereSomewhereFight. May involve a TrialByFriendlyFire.

'''WARNING: Some of these are a little detail heavy, so SPOILER alert.'''

* ''Videogame/Portal2'' has [[spoiler: Wheatley]]. This little guy starts off as your friend slash guide, helping you evade [=GLaDOS=]'s sight and saving you numerous times. At the end of Chapter 5, you get the chance to place [[spoiler: Wheatley]] in [=GLaDOS=]'s body, effectively putting him in control of the entire facility. He calls up the escape lift and as you ride it up to the surface, he excitedly rambles on about how small you are and how huge he is. [[spoiler: And then he starts laughing. And the laughter doesn't stop, instead turning [[EvilLaugh maniacal]] as he [[FaceHeelTurn calls he lift back down]]. It turns out he's become DrunkWithPower, and you must team up with [[EnemyMine [=GLaDOS=]]] to defeat him and prevent him from exploding the place with gross incompetence. Wheatley is the BigBad for the rest of the game and serves as the FinalBoss.]]
* Several ''Franchise/FinalFantasy'' games use this trope:
** [[spoiler:Doga and Unei]] in ''VideoGame/FinalFantasyIII''. Especially annoying because it's a [[spoiler:tough SequentialBoss with no healing in the middle...]] even though they're ON YOUR SIDE!
** Baku in ''[[VideoGame/FinalFantasyIX IX]]'' is the WarmupBoss variant.
** Kimahri is an interesting case when you fight him in ''VideoGame/FinalFantasyX''. He's not exactly Tidus' friend (at first) and he ambushes him on the road to the boat, initiating a DuelBoss battle. Wakka breaks up the fight after the two exchange a few blows and the reason Kimahri attacked Tidus was because he didn't trust him around Yuna when they first met, even though both he and Tidus are supposed to be on the same side (protecting Yuna on her pilgrimage).
** [[spoiler:Rikku and Paine]] in an optional series of fights in ''[[VideoGame/FinalFantasyX2 X-2]]''.
** [[spoiler:Vossler]] in ''[[VideoGame/FinalFantasyXII XII]]''.
** [[spoiler:Kain and Yang]] in ''[[VideoGame/FinalFantasyIV IV]]'' as the mind control variant. [[spoiler:Cecil's former self]] also has to be fought, but the hook here is [[SheatheYourSword not to harm him.]]
** ''VideoGame/FinalFantasyTacticsAdvance'' has one battle where you have to fight [[spoiler:Ritz]] in order to get to the final area of the game. She has no hard feelings against Marche, but just doesn't want him to progress any further.
** ''VideoGame/FinalFantasyTacticsA2'' does it again with [[spoiler:Adelle, who gets brainwashed by Illua after leaving your clan, and then in her possessed state, she and some monsters fight you for the grimorie while you have Luso try to talk some sense into her.]]
** Hell, even in ''VideoGame/DissidiaFinalFantasy'', Terra gets mind controlled into fighting one of the heroes, Cloud fights Firion to test the strength of his dream, [=WoL=] and Squall fight etc. It's not uncommon. The biggest difference between "friendly" fights and actual fights is that at the end, both heroes are still feeling all right, showing it was just a sparring match[[note]]The exception is Firion vs. Cloud, where Firion gets his butt royally handed to him, and almost loses control, coming close to seriously injuring Cloud[[/note]].
** [[spoiler:Fran and Balthier]] in ''VideoGame/FinalFantasyXIIRevenantWings''. Making this worse is that it's probably the hardest fight in the game, and that the whole thing is a stupid misunderstanding.
* ''VideoGame/TheNamelessMod'' features this in the [=WorldCorp=] storyline. You'll be forced to fight [[spoiler: Slicer and Deus Diablo at some point. You also attempt to fight Phasmatis at one point, but this goes nowhere since he is effectively immortal.]] And if you attempt to do the [[spoiler: Ryan]] ending on a [=WC=] playthrough, you'll get this with [[spoiler: Kylie]] if you have rekindled your relationship with her.
* ''[[VideoGame/TwentyTwentySeven 2027]]'' has this with [[spoiler: Magnus]] at the end of the game, or not, depending on your choices.
* ''Franchise/MegaMan''
** Done very well in ''VideoGame/MegaManX5'', with X vs. Zero. It helps that there are actually 3 possible intros to the fight, depending on who you're playing as and [[spoiler:whether Zero "awakened" to his SuperpoweredEvilSide.]] It also helps that the ending of one of the previous games hinted that something like this would happen.
** And [[VideoGame/MegaManX4 one game before that]], Zero is forced to fight Iris. [[ILetGwenStacyDie We all know how that went]].
** ''VideoGame/MegaManStarForce'': In the first game Geo is forced to fight Bud, Sonia and Luna when they are tricked by the evil FM-Ians (Taurus, Lyra and Ophiuca), into getting revenge against people who wronged them (i.e. Vaughn and Veil Platz for Luna, Luna and Geo for Bud and Chrys Golds for Sonia). Then in the second game as both Bud and Luna are taken over by what Omega-Xis calls residual energy and then as Vega and Hollow trick Sonia into doing their dirty work for them. Finally in the third game as Taurus becomes corrupted by the bad guys and is forced to merge with Bud as a result of it.
** ''VideoGame/MegaManZX'' Vent/Aile are forced to fight their [[ParentalSubstitute guardian]] Giro, who's been brainwashed by [[BigBad Serpent]] and they need to BeatTheCurseOutOfHim. [[HopeSpot It works]]...and then Serpent blasts Giro and Vent/Aile, and Giro (due to his existing injuries from the fight) is fatally wounded as a result and needs to perform a HeroicSacrifice to save Vent/Aile.
* ''Franchise/DragonAge'':
** In ''VideoGame/DragonAgeOrigins'', you have to fight [[CoolOldLady Wynne]] and Leliana if you choose to despoil the Urn of Sacred Ashes while they are in your party.
*** You will also have to fight Wynne if you choose to ally with the Templars while doing the "Broken Circle" quest.
** In ''VideoGame/DragonAgeII'', you can end up fighting several of your companions in the end game if you don't push their Friendship or Rivalry all the way to the extreme.
** In the ''Trespasser'' DLC of ''VideoGame/DragonAgeInquisition'', you will have to fight [[spoiler:the Iron Bull, if you sacrificed the Chargers in the main game. There is ''no hint'' of this ahead of time, and it comes as a particular PlayerPunch if he was romanced.]]
* In Atlus's ''VideoGame/DigitalDevilSaga'', [[spoiler:Serph and Heat stage a fight between themselves in an attempt to make the local villain drop his guard.]]
** In the sequel [[spoiler: Gale, Sera and Cielo take on Heat after he eats Serph and turns into a OneWingedAngel, to a DarkReprise of the first game's battle theme]]. Subverted in that [[spoiler: Heat's on a slightly different agenda but they're aiming for the same goal and they still consider Heat a comrade]].
* The ''Manga/MagicKnightRayearth'' SNES game featured a sequence where one of the trio had to fight the other two. This is one of the last variety, where the other guys are being mind-controlled, and in fact, you're supposed to ''lose''; if you kill them, you get a game over. This is actually made kind of hard, or at least boring, by the fact that their AI is utterly crappy and it can take ''forever'' for them to kill you with their piss-weak attacks.
** The same case happened in the anime: in one episode, Hikaru and Umi were BrainwashedAndCrazy thanks to the still not {{Heel Face Turn}}ed [[MasterOfIllusion Caldina]], therefore Fuu had to fight and disable them on her own.
* Happens a bit in ''VideoGame/TacticsOgre''. You are guaranteed to fight Vice at least once in the game (The reasons differ, though, between him making a FaceHeelTurn or accidentally getting caught in a bad spot), Leonard often fights you, Guildus is reanimated into a death knight, and in one path, Denim's sister Kachua is so angry at you she ''actually stays behind in the fight against Lans Tartare!!'' (In other chapters, Lans tells her to run away and she obliges.)
** Tactics Ogre's GaidenGame[[spoiler:/{{Prequel}}]], ''[[VideoGame/TacticsOgreTheKnightOfLodis The Knight of Lodis]]'' also does this. In Path A, Orson is fought, and then Rictor is possessed, making you fight him twice. But in Path B, Rictor is only fought once and it is instead Cybil who is possessed by the BigBad. The first Rictor battle happens regardless of path choice, as does the battle with the mermaid Aerial.
* In ''VideoGame/YuGiOhNightmareTroubadour'', one section of the game pits you against a mind-controlled Joey. Winning ''or'' losing this battle results in a Game Over, so you have to use particular cards to make the game end in a draw. (This comes straight from the series, though it had a different explanation.)
* In ''VideoGame/BlueDragon'', when you encounter Marumaro for the first time, he will fight you to prevent you from interfering with his quest for medicine for his village.
* In ''VideoGame/IronTwilight'', when Qem jumps out of the chest and will only help you if you beat him in some sort of [[TennisBoss tennis match with fireballs instead of tennis balls]] [[GiantSpaceFleaFromNowhere that has no relevance to the plot whatsoever]].
* The UsefulNotes/SuperFamicom game ''Anime/TenchiMuyo Game Hen'' has everyone's favorite SpacePirate Ryoko Hakubi as a late-game boss, following her [[DamselInDistress abuction]] by the BigBad halfway through the story. It's a bit of a subversion in that defeating Ryoko earns the player a Game Over; the object of the mission is to defeat the Ryoko ''clones'' (easily identifiable as [[PaletteSwap recolors]] of the real one) who are acting as the real one's {{flunk|yBoss}}ies.
* ''VideoGame/{{Xenogears}}'' uses this trope several times too. There's only three party members you don't fight at some point in the story.
* ''VideoGame/AdvanceWars: Dual Strike'' features a version of this, in which potential allies pit their armies against yours in order to test your skills as a commander.
** From the first ''Advance Wars'' there's ''Rivals!'', a secret mission you can get if you use a certain CO on specific missions. It's the same.
*** Alternatively, it's just like modern military exercises. Just ignore the explosions. Heck, it could even be a computer simulation.
* In the first dungeon of ''VideoGame/{{Fallout 2}}'', the main character must fight a fellow tribesman to display his worthiness. If you're [[StatisticallySpeaking smart enough]], you can opt to talk your way out instead.
* Performed spectacularly in ''VideoGame/ChronoCross''. After defeating Lynx atop Fort Dragonia, Serge is [[spoiler:body-swapped with his nemesis, but the two other members in the party never notice.]] At that point, your friends and [[spoiler: Lynx in Serge's body]] attack you and you must defend yourself. The odd part is, you're actually given the chance to ''win'' (but what kind of heartless monster would beat his own friends into a pulp?) The outcome of the battle is the same whether you win or lose, however.
** Battling the Dragon God (the fusion of the Six Dragons) is one such battle, since [[spoiler:Harle, the Lunar (Seventh) Dragon, merges with it irrevocably also]].
* The major boss fights (against Trinity and Seraph) in ''VideoGame/EnterTheMatrix'' are like this. The former is a sparring match between friends. In the latter case... he fights EVERYONE he meets with, apparently.
* Happens in every ''VideoGame/TalesSeries'' game, with the exception of VideoGame/TalesOfPhantasia.
** ''VideoGame/TalesOfEternia'' pits you up against [[spoiler:the GuestStarPartyMember]].
** ''VideoGame/TalesOfTheAbyss'' also does it the least since the only friend you fight is Asch...No one's sudden betrayals actually result in a battle.
** ''VideoGame/TalesOfRebirth'' goes ''crazy'' with this trope. In ''VideoGame/TalesOfRebirth'', you fight [[spoiler:every single party member, including the hero at some point, including a fistfight between Veigue and Tytree as the result of an argument about Veigue not being open with his feelings. Pretty much the only character you don't fight EVER is [[{{Keet}} Mao]]]]. (Unless you count the training battle)
** Like ''VideoGame/TalesOfRebirth'', ''VideoGame/TalesOfSymphonia'' also has a little ''too'' much fun with this trope...but not to the point described above.
*** The Sequel includes a possible final battle but this is one where you're supposed to lose, winning results in the DownerEnding.
** Done pretty well in ''VideoGame/TalesOfVesperia'': [[spoiler:After the latest argument between Flynn and Yuri about what Yuri's doing, Flynn seems to finally give up,]] until Yuri offers him a way to make his point: a swordfight.
--->'''Yuri''': You're not going to beat me in an argument. But you know what you ''can'' beat me in... (holding up his sword) This.
*** The two then proceed to trash-talk each other while beating each other up. They feel better afterwards, but [[spoiler:Flynn still loses the argument.]]
---->'''[[spoiler:Flynn]]''': I can't even win with a sword anymore.\\
'''Yuri''': (teasingly) Hahaha... Loser.
*** Yuri also fights [[spoiler:a BrainwashedAndCrazy Estelle]] in an IKnowYoureInThereSomewhereFight.
*** The [=PS3=] version adds several more opportunities to fight your friends, most notably [[spoiler:in the team battle mode in the coliseum, the final battle of which will pit all the party members you're not using against the party members you ''are'' using.]]
*** Also in the arena, Karol (in a poor disguise and loudly claiming not to be Karol) will fight alongside his Hunting Blades guildmates if he's not in your current party. In addition [[spoiler: if Raven isn't with you he'll appear as Captain Schwann alongside the Schwann Brigade also claiming not be Raven, although he's aware he's fooling no one]].
** ''VideoGame/TalesOfXillia'' has [[spoiler: Jude]] get into a scrap with [[spoiler: Alvin]] after the latter goes too far in trying to snap him out of a HeroicBSOD. Additionally, the EX arena will have either Jude or Milla face off against every other member of party in three pairs, then go one on one with the character you didn't pick.
** ''VideoGame/TalesOfXillia2'' has a similar occurrence to its prequel, with your choice of [[spoiler: Jude]] or [[spoiler: Milla]] trying to snap [[spoiler: Ludger]] out of a HeroicBSOD. The EX Tag Arena also pits you against one of your party members teamed with any of a number of different bosses for its last opponents.
* In ''VideoGame/{{Touhou}}: Lotus Land Story'', [[FriendlyRivalry Reimu and Marisa]] end up dueling in Stage Four over who will get to explore a mysterious, monster-haunted mansion. This is referenced several games later in ''Imperishable Night'', where you'll fight either Reimu or Marisa depending on which team you chose at the game's start, when they mistake you for the perpetrator of the endless night. In both cases, this is the point where [[ThatOneBoss the game's difficulty spikes dramatically]].
** In ''Ten Desires'', the Stage 1 boss is Yuyuko Saigyouji, the FinalBoss of ''Perfect Cherry Blossom''. She's actually holding back and only serves as as WarmupBoss, and after she's defeated gives the protagonist directions toward resolving the latest Incident. Applies especially if playing as Youmu Konpaku, her servant.
** In the fan game ''VideoGame/ConcealedTheConclusion'', it's revealed that Gensokyo is going through a DreamApocalypse and there's nothing anyone can do about it, [[TheLastDance so Marisa challenges Reimu to one last battle, for old time's sake.]] Unlike in the canon games, this fight is played for pure drama.
* The third stage of ''VideoGame/MagicalBattleArena'' has your character finding her respective ally ([[Franchise/LyricalNanoha Nanoha and Fate]], [[OriginalGeneration Sarara and Kirara]], [[{{LightNovel/Slayers}} Lina and Naga]]) only for the [[UltimateShowdownOfUltimateDestiny rules of the universe forcing them to fight]] to get out of their current area. The only ones that doesn't are [[Manga/CardcaptorSakura Sakura]] and [[Manga/MagicalCircleGuruGuru Kukuri]], who instead invokes DefeatMeansFriendship on each other for the team battle on the next stage, and [[TheDragon Ruru]] and [[BigBad Nowel]], who will go through said team battle solo.
* ''VideoGame/PaperMario'':
** In ''VideoGame/PaperMarioTheThousandYearDoor'', one boss fight has you fighting a traditional boss but your allies are fighting alongside him. This is because [[spoiler:said boss [[GrandTheftMe took over Mario's body and identity]], leaving the real Mario as a literal shadow of his former self]].
** Also, Mario is forced to fight [[spoiler:a possessed Princess Peach, who is now the Shadow Queen.]]
** In ''VideoGame/SuperPaperMario'', there's a variant: [[spoiler:the FinalBoss is a fusion between Dimentio, Luigi and the Chaos Heart, with Dimentio's personality in control.]]
* A subversion of this occurs in ''VideoGame/{{Bayonetta}}'' where it's revealed that Jeanne, who is fought on multiple occasions, is actually the protagonist's brainwashed childhood friend.
* Happens ''VideoGame/TheLegendOfZeldaTwilightPrincess'', wherein you must fight [[spoiler:a possessed Princess Zelda.]]
** And once more in ''[[VideoGame/TheLegendOfZeldaPhantomHourglass Phantom Hourglass]]'', in which the final boss is actually [[spoiler:your buddy Linebeck possessed by Bellum]].
* In ''[[VideoGame/SoulSeries Soul Calibur II]]'', an odd version happens in both Kilik and Xianghua's story modes. While the majority of characters fight against their enemies, these two fight because they don't want the other to go on to face [[BigBad Inferno]] and potentially be killed.
** And to a lesser extent in the same game, Seong Mi-Na defeats Yun Seong because it's "no place for kids." Presumably she's thinking of herself in terms of the ChristmasCake definition of "old".
* ''VideoGame/WorldOfWarcraft'' has several. Vaelestrasz in BWL tries to beat the main boss before you get there and loses, gets partially mind controlled so he has to fight you and is weakened throughout. Considering how tough he is, it's a wonder Nefarian managed to beat him, really...
** Kalecgos, the first boss of Sunwell Plateau is a blue dragon who tried the same thing. His will is stronger or something, because you beat him by killing the monster possessing him. His ally, the third boss Felmyst was not so lucky, probably because she is some sort of undead monster by that point.
** Keristrasza! I'm noticing a pattern here. Dragons don't seem to have very much luck when they try doing our job or helping us, do they?
*** Indeed, by this point about half of the dragons fought in the game are former allies. Sapphiron and Nightbane may also count, being reanimated dragons.
** The various keepers of Ulduar have all been brainwashed by the [[EldritchAbomination Old God Yogg-Saron]], forcing you to fight them. Once defeated, they realize what's happening and offer to help you against the Old God.
** The Argent Tournament includes the player killing a lot of the Crusade's members and beating up their bosses.
** After defeating the corrupted Shado-Pan in their Monastery, the remaining defenders challenge you to battle to determine if you're prepared to fight against the Sha.
* ''VideoGame/{{Persona 3}} FES'': [[spoiler:Aigis and Metis must defeat the rest of SEES team (except [[MissionControl Fuuka]]) to get the true key.]]
* ''VideoGame/BaldursGate II''. Fellow escapee and very charming thief Yoshimo has no choice but to go apeshit half way trough the game because of an unbreakable Geas oath. So yeah.) and fight with the PC. He doesn't get better, though you can deliver his heart to his church to give him some forgiveness in death.
* In ''VideoGame/TheWorldEndsWithYou'', you finally fight the Conductor, who [[spoiler:takes control of Shiki using the Red Skull pin. This leads to a cutscene in which the still-possessed Shiki launches a final attack which knocks out Beat, but Neku knocks her out and slices her Red Skull pin, ending the possession.]]
* ''VideoGame/MeltyBlood'' occasionally has the Back Alley Alliance of Satsuki and Sion fighting each other to prevent the other from getting killed.
* ''VideoGame/ResidentEvil5'' features a boss fight where Chris and Sheva end up fighting [[spoiler: Jill Valentine]].
* ''VideoGame/CastleCrashers'' has this happen if you're in a multiplayer game. After rescuing a princess, the players fight to the last man to decide who gets to kiss her. Even though you can brutally cut down the other players, everyone will start the next level alive and well.
* In ''VideoGame/MetalSlug 6'', one of the characters that you did not choose is under mind control and fights you. They can use the same weapons you can, switch them at will, and can use their melee weapons just like you can. Defeating the creature controlling the character frees the victim.
** This also happens (sort of) in 3, where your character is abducted by aliens and you have to play as a different one to recover them. Along you way you fight legions of clones of the captured character.
* Happens fairly often, usually via Mind Control, in the ''VideoGame/SuperRobotWars'' series.
** In ''VideoGame/{{Super Robot Wars Original Generation}}s'', this has tallied up quite a lot. BrainwashedAndCrazy victims include Kusuha (twice, by [[spoiler:Ingram]] and ODE), Excellen (twice too! By [[spoiler:Ingram, but this one got thrown into CanonDiscontinuity]], and Einsts, especially Alfimi) and Lamia (twice in the same game: first ODE, then Duminuss), and the rest of the ODE victims. The first game, however, pits you against Sanger (who's been fighting with you for the first few stages) in a convoluted plot of StealthMentor.
** In [[http://www.youtube.com/watch?v=rFeKFc0peH8 Chapter 10]] of ''VideoGame/SuperRobotWarsMX'', Duke Fleed in ''Anime/UFORoboGrendizer'' has to to fight Anime/GreatMazinger (piloted by Blacki) and Anime/MazingerZ piloted by a brainwashed Kouji Kabuto. Eventually, he breaks Kouji free and defeats Anime/GreatMazinger with his help.
** For some reason, the subplot of having to fight the SMS (except Alto) from ''VideoGame/{{Macross 30}}'' was the only thing they adapted from that game in ''VideoGame/SuperRobotWarsBX''. But since there's no [[Anime/MacrossPlus Sharon Apple]] to mind control them in BX, they just made them part of the Marder Army by holding the crew of the Macross Quarter hostage.
** In ''VideoGame/SuperRobotWarsV'', [[spoiler: whoever you chose as the protagonist will have to fight the other protagonist at some point in the game.]] And before that, Tetsuya and the Great Mazinger leaves the group after they beat the Fourth and Fifth Angels. He reappears after Mazinger Z learns how to use the Iron Cutter attack and attacks Mazinger Z because he's afraid that Mazinger Z is [[spoiler:turning into Mazinger ZERO]]. He also attacks the Black Getter and causes Go to show up with Shin Getter Robo, reuniting Ryoma with Hayato and Benkei in the process. Later, Tetsuya's proven right and has to team up with Shinji [[spoiler:(who is piloting the Awakened EVA-01)]] and the others in order to stop the threat.
* [[spoiler:Pixy]] is fought twice in ''VideoGame/AceCombatZeroTheBelkanWar''.
* ''Franchise/MetalGear'' has a number of these.
** In ''Metal Gear Solid'' Snake has to kill [[spoiler: his old friend Gray Fox]] a second time.
*** During the battle with Psycho Mantis, Snake has to fight [[spoiler:Meryl]] without delivering a killing blow. If that person dies, you get a NonStandardGameOver.
** And of the ''Ac!d'' spin-off series, a fight with [[spoiler:Venus]].
** [[spoiler:The fight with the Boss in ''Solid 3'' may count as well, considering the whole mission and her defection were all a ruse to avoid a potential war between East and West, and she was pretty much dying for her country.]]
* ''Franchise/KingdomHearts'' does this a few times. It happens twice with Riku in [[VideoGame/KingdomHearts the first game]]. He is first evil and is jealous of you, then attacks, and the next time he's possessed by darkness and becomes ThatOneBoss for several players.
** ''[[VideoGame/KingdomHearts358DaysOver2 358/2 days]]'' ends with [[spoiler: Xion committing SuicideByCop against Roxas.]]
** In ''VideoGame/KingdomHeartsBirthBySleep'' Aqua has to fight [[spoiler:both her friends, Ventus possessed by Vanitas at the end of her chapter, and Terra possessed by Xehanort in the final chapter. Both of these characters are being directly controlled by another though and in fact will help Aqua out by resisting as best they can.]]
** Pops up in ''VideoGame/KingdomHearts3DDreamDropDistance'' as well. [[spoiler:The final boss of the game is Sora (or more specifically, the Nightmare possessed suit of armor he's wearing).]]
*** And earlier in the ''Film/TronLegacy'' world, [[spoiler:Sora is forced to fight Tron, who at this point in time is known as Rinzler. He's not technically the Tron Sora knows, who came from a copy of the original Grid, but that doesn't make it any easier on Sora.]]
* In the C path of ''VideoGame/ValkyrieProfileCovenantOfThePlume'', [[spoiler: every friend you sacrificed to the Plume [[PlayerPunch is now an einherjar fighting on Valkyrie's side against you]].]]
* ''VideoGame/{{Xenosaga}}'' stayed away from this trope until Episode III when [[spoiler: you had to fight Shion after Kevin convinced her that siding with him was the only way to be happy]].
* The final battle of ''VideoGame/{{Mother 3}}'' is a great example of this, in which [[spoiler:Lucas must fight his brother Claus, who has no idea who he actually is. However, for most of the fight, Lucas refuses to attack. By the end, Claus realizes who he is and commits suicide.]]
* The battles against [[spoiler: Rundas, Ghor, and Gandrayda]] in ''VideoGame/MetroidPrime3Corruption'' definitely count. They all help you at various points through the game, and in the 75% ending, [[TheStoic Samus]] mourns their deaths.
* In the final battle in ''VideoGame/BeyondGoodAndEvil'', the BigBad possesses (and clones) Jade's friends, complete with mind fuck. ("It's your fault we're suffering!")
* In the Chicago History Museum mission in ''VideoGame/{{Stranglehold}}'', [[spoiler:your ally for most of the game, Jerry Ying, betrays you and murders Billie after you take down Damon Zakarov. After you chase his ass down, the BossBattle begins with Jerry revealing that he acted on orders from Wong, the "same guy who sent you to find her."]]
-->[[spoiler:'''Jerry:''']] We're in a hell of a business, old buddy! Nothing's ever what it seems!
* This becomes more and more the case with Franchise/{{Pokemon}} [[FinalBoss League Champions]] through the first four "generations" of games. In Red/Blue, it's your {{Jerkass}} [[TheRival Rival]]. In Gold/Silver, you have Lance, who is on the side of GoodIsNotNice and is all "I see potential in you; now I'll try to utterly crush you to see if I'm right". In Ruby/Sapphire you have Steven who's pretty much your chum. Then in Diamond/Pearl you have Cynthia, the do-gooder AdventurerArchaeologist who wants to be your BFF, helps you save the world and wants you to know this whole battling-you thing is ''tremendously fun'' for her. ''Then'' in Black/White you have Alder, a kindly old man who [[WalkingTheEarth walks the earth]], does his best to give you a hand and has the most festive and upbeat battle theme ever. In the sequels, we have Iris, who's a cute kid and tries to help you at a couple points in the game. At this rate it won't be long before we have a game where the League Champion is a Franchise/{{Care Bear|s}}.
** While your rivals in the first two generations of the game are both {{Jerkass}}es, [[VideoGame/PokemonRubyAndSapphire May/Brendan, Wally]], [[VideoGame/PokemonDiamondAndPearl Barry]], [[VideoGame/PokemonBlackAndWhite Cheren, Bianca]] and [[VideoGame/PokemonBlack2AndWhite2 Hugh]] are all considerably friendlier.
** In ''Black 2'' and ''White 2'' the side-area [[BossBonanza Pokémon]] [[ContinuityPorn World]] [[InevitableTournament Tournament]] has a unique battle type: Mix Battles. Here, the opposing battler will take one Pokémon (or two, in Triple Mix Battles) from your party and you have to switch with one of theirs. Figuring out how to take down your own party member can be a tricky business.
* ''Franchise/StreetFighter'' has indulged in this trope more than a few times, most prominently in ''VideoGame/StreetFighterAlpha 3'' and (''Super'') ''VideoGame/StreetFighterIV''[='s=] Rival Battles.
** ''Alpha 3'': {{Bi|gBad}}son abducts Ryu and [[BrainwashedAndCrazy injects him with a portion of his Psycho Power]], forcing ''[[TheRival Sagat]]'' [[IKnowYoureInThereSomewhereFight to try and]] [[RousingSpeech rouse him]] out of this as [[BackToBackBadasses Ken and Sakura]] face Bison. Also, the Bushin {{ninja}} [[VideoGame/FinalFight Guy]] tries to reach out to [[VitriolicBestBuds his best friend]] Cody, [[TragicHero who has gone]] from the hero of Metro City [[DarkerAndEdgier to]] an [[StrawNihilist apathetic]], [[DeadpanSnarker snarky]], [[BloodKnight fight]]-''[[DeconstructedTrope addicted]]'' [[KnightInSourArmor brooder]], as he believes that deep down, Cody still holds some goodness in his heart.
** ''IV'': [[FortuneTeller Rose]] believes that Ryu is TheChosenOne destined to defeat Bison, but doesn't want him to preemptively rush into danger (according to her visions, he can vanquish Bison ''only'' at a specific time). On the other end, Guy tries to prevent Rose from facing Bison herself because while she intends to eradicate ([[HeroicSacrifice or at least]] [[TakingYouWithMe stall]]) Bison, [[SenselessSacrifice she has seemingly resigned herself to death and holds a far greater importance to the world than she believes]] (he tried this before in ''Alpha 3'' but failed, leading Rose to eventually be [[GrandTheftMe possessed by Bison]] in the interim between ''Alpha 3'' and ''II''; it should be noted that he and Rose were not TrueCompanions at this point). Cue battle (and some [[RelationshipWritingFumble unintentional]] ShipTease). He also confronts Cody again, mainly for the same reasons as their fight several years prior, as well as trying to convince Cody to [[BashBrothers join him]] in the fight against Seth and S.I.N.
* A meta example in ''[[VideoGame/LEGOAdaptationGame LEGO Star Wars]]'', as while the final boss isn't technically on your character's side, there's the fact that, in a multiplayer game, IT'S THE OTHER PLAYER.
* ''VideoGame/AgarestSenki'' has Valeria fighting against you in the 2nd generation when Ladius runs away from his enemies, forcing two childhood friends to fight against each other.
** In ''Agarest Senki 2'', this happens twice in the entire game. It happens first with [[spoiler: Sophia because Gray gets a GrandTheftMe from Chaos and she doesn't trust Chaos herself]]. The second one only happens if one goes to the Bad Ending and that is [[spoiler:Eva who pulls off a FaceHeelTurn when the party minus the protagonist Gray decides to kill Chaos because Gray gets KilledOffForReal]].
* In ''VideoGame/ShirenTheWanderer 3'', Shiren and Asuka fight because Sensei disagreed with her. Even if you have Shiren say that Asuka's right, the fight happens anyway (and Sensei backs out of the fight, which Koppa calls him out for) So, basically, they're fighting because they had Sensei as a boss, so why not Asuka?
* The penultimate fight of Story Mode in ''VideoGame/MortalKombat9'' is [[spoiler:Raiden vs. Liu Kang.]] '''[[TearJerker It doesn't end well.]]''' It also happens a bit earlier in Kitana's chapter, where she duels her [[HeterosexualLifePartners servant]] Jade (the latter having been sent by Shao Kahn to keep an eye on Kitana). This fight isn't nearly as emotionally heartwrenching [[spoiler:and doesn't come at the cost of presumably destroying a long-lasting friendship unlike the former.]]
** ''VideoGame/MortalKombatX'' has this in spades. [[spoiler:Due to most of the Earthrealm warriors dying in the previous game, Quan Chi claimed their souls and they serve under him as revenants. Sub-Zero, Jax, Kung Lao, Liu Kang, Stryker, Sindel, Smoke, Nightwolf, and Kitana are under Quan Chi's control and you fight them all eventually. Jax and Sub-Zero are able to be saved and return to their normal selves, but the rest aren't as lucky, as Scorpion offs Quan Chi [[RevengeBeforeReason without realizing why he was needed]], permanently dooming the revenants to stay as these.]]
* Like any other fighting game worth its salt, ''VideoGame/BlazBlue'' has cases of this. The above quote is a lampshade by Makoto, who was forced into fighting Tsubaki just to keep her from [[MurderTheHypotenuse killing Noel]]. She even went out of her way to ''forge an order to withdraw'' just to avoid hurting Tsubaki herself, and the fighting was pretty much a last resort.
-->"I didn't want to have to do this... but neither of us have a choice, do we...?"
** In ''[[VideoGame/BlazBlueChronophantasma Chronophantasma]]'', this happens a ''lot'' to [[spoiler:Litchi Faye-Ling. Just because she is now in the NOL doesn't mean she discarded the friendship she built up to the likes of Taokaka and Bang Shishigami. Making matters worse, her "mission" involves striking at Bang to snatch something he treasured, and in the previous game, she has come to treat him as a very good friend. In her Arcade route win quotes, she is borderline crying after defeating Bang]].
* TheDragon of ''VideoGame/NeverwinterNights2'' will try to convince some of your party members to join him and the BigBad against you. If you fail Influence checks with these characters, they will be swayed. Special mention goes to Qara and Sand: their rivalry means it is literally impossible to keep one without having the other turn on you.
* The granddaddy of them all: ''VideoGame/DoubleDragon''. In the arcade version, if two people are playing, the game ain't over after the final boss is defeated... Billy and Jimmy then have to fight each other to the death, and Marian ends up with the winner.
** Also shows up in ''VideoGame/DoubleDragonNeon'', though only ''after'' the credits, and without the "to the death" part.
* After defeating Apocalypse in ''VideoGame/XMenVsStreetFighter'', the player's two characters stand there and congratulate each other. The player, however, ''can'' recover control of his/her character and attack the partner. Do so two times and a battle ensues. (The [=PS1=] and Saturn ports lack such options, and the player has to fight their partner after Apocalypse regardless.)
* In ''VideoGame/LittleSamson'', just as the party all comes together, Kikira turns on Little Samson and starts the first BossBattle because, the manual says, she "may need some coaxing by Samson to obey."
* This is a staple of the ''VideoGame/{{Neptunia}}'' series. A fair amount or sometimes even most of your party members will have a boss battle (or two or three) due to various circumstances. They want to test you, they want to prove that they're better than you, you have a temporary conflict of interests, there's a misunderstanding, etc. [[spoiler:One standout case however is the Conquest Ending of ''VideoGame/HyperdimensionNeptuniaMk2'' where Nepgear has to fight and kill all the other goddesses. Unlike the other conflicts listed here, this one is just as dark as it sounds.]]
* Happens in ''VideoGame/GuildWars'' in the final mission, where the party must fight their former mentor and ally, Prince Rurik. Or rather, his decomposing zombified corpse. The Prince apparently has control of his vocal functions, but cannot control his actions due to a spell being put on him by the Big Bad of that campaign. He makes it clear that he doesn't wish to fight his comrades, but has little choice in the matter. Winning the fight causes poor Rurik to be KilledOffForReal, but ends the Lich's spell, setting him free and allowing him to finally pass on.
* ''VideoGame/{{Skullgirls}}'' has a couple instances:
** Filia and Painwheel.
** Samson and Leviathan, the parasite partners of Filia and Squigly, respectively. Granted they behave more like VitriolicBestBuds, but they mostly instigate their battle because they disagree on whether the Skullheart should be pursued.
** And of course Peacock and [[spoiler:[[BigBad Marie]]]].
* The ''VideoGame/{{Suikoden}}'' series does this often, most notably:
** ''VideoGame/SuikodenII'': The duel between Riou and his best friend, Jowy, which gets briefly postponed when [[spoiler: Gordo's]] men mortally wound [[spoiler: Riou's adopted sister, Nanami]]. In the end, if Riou has recruited all [[OneHundredEight 108 Stars of Destiny]] before the final battle, he can [[spoiler: spare Jowy's life and get the best ending]].
** ''VideoGame/SuikodenV'': About midway through the game, the Prince has to battle his friend [[spoiler:who's also his sister's bodyguard, [[http://www.youtube.com/watch?v=OxuufS4-5kc Miaskis]]]], which serves as the conclusion of the liberation of Doorat and doubles as a massive TearJerker.
* ''[[VideoGame/ArtOfFighting Art of Fighting 3: Path of the Warrior]]'': Just before the conclusion of the game's story mode, Ryo and Robert battle each other to determine which of them will go on to face [[BigBad Wyler]]. According to canon, [[spoiler: Robert won.]]
* In ''VideoGame/{{Strider}} 2'', Hiryu and Hien were once best friends before Hien decided to betray the Striders and lead them to their ruin. Even though he's now sided with the BigBad, Hien still considers Hiryu a friend and tries to convince him to abandon his mission and join his side, but Hiryu quickly turns him down and advises him to fight seriously next time they meet.
** This is expanded upon in the crossover game ''VideoGame/NamcoXCapcom'', where Hien tries until the very last second to convince Hiryu to abandon his mission to kill Meio, but Hiryu turns him down (and defeats him) every time. It's not until the very last chapter, and once Meio gives him the explicit order to kill him, that Hien gives up on trying.
* ''VideoGame/NamcoXCapcom'' has several other such cases, like VideoGame/WonderMomo not wanting to hurt Amazona, a fellow actress from her play which has ben Brainwashed by the enemies or [[VideoGame/{{Tekken}} King]] being distressed at his mentor Armor King being on the enemy side.
* In ''[[VideoGame/LunarEternalBlue Lunar 2: Eternal Blue Complete]]'', Ghaleon decides to abandon the CorruptChurch he's been serving and even is willing to give the party his CoolAirship... after he tests Hiro's skills on a one-on-one battle to see his worth, that is!
* In ''VideoGame/SonicHeroes'', the four teams will encounter two of the other three during their adventure. Team Sonic battles Team Rose when Amy tries to get Sonic to marry her, Team Rose battles Team Chaotix when Team Chaotix tries to get Cheese, Team Dark deals with Team Sonic when Sonic and Shadow's rivalry kicks in again and Team Chaotix and Team Dark have it out over their business with Eggman.
* In ''VideoGame/LiveALive'', the training in the Kung Fu chapter consists of a series of one-on-one fights with your pupils.
* In ''VideoGame/StarFoxAssault'', [[spoiler:General Pepper is at one point possessed by the Aparoids, losing control of his body and flagship. He's still conscious, but can't control himself anymore, so he urges Fox to shoot him down and kill him before the Aparoids fully take him over. Fortunately, once he is defeated, Peppy manages to save him from crashing and dying, and Pepper makes it out wounded, but OK.]]
* The ''Franchise/ShinMegamiTensei'' series as a whole has this as a mainstay.
** In ''VideoGame/ShinMegamiTenseiI'', the three party members are the Heroine, the Law Hero, and the Chaos Hero. The Heroine sides with the player no matter what, but [[spoiler:it's mandatory to kill at least one of the others. If you side with Law, you have to kill the Chaos Hero and vice versa. If you don't pick a side and instead go for Neutral, you have to kill both of them. Even if you do side with them, they die anyways: the Law Hero is killed by the Chaos Hero, and the Chaos Hero steals an ArtifactOfDoom from the player and dies from too much power.]]
** As ''VideoGame/ShinMegamiTenseiIV'' reaches its conclusion [[spoiler:you will have no choice but to fight two of the three companions that you were with for the entire game because they will disagree with whichever path you have chosen for Tokyo. It's made slightly easier with [[LawfulGood Jonathan]] and [[ChaoticGood Walter]], but only because each has already sacrificed his own body to become an all-powerful EldritchAbomination. The battle with [[NeutralGood Isabeau]], however, is undoubtedly the most heartbreaking PlayerPunch that the game has to offer.]]
** ''VideoGame/ShinMegamiTenseiIVApocalypse'' also has a PlayerPunch in [[spoiler:the Massacre route. This route would mean the destruction of the universe, and the party understandably turns on the player. After spending the entire game showing off CharacterDevelopment for the party, killing them is heartwrenching.]]
* ''{{VideoGame/Xenoblade}}'' features two such bosses: [[DamselInDistress Fiora]] piloting Face Nemesis (in which the goal is not to kill her) and [[spoiler: [[CoolOldGuy Disciple Dickson]]]] (in which the goal is to kill him). The latter is less of a PlayerPunch, since by that part of the story, [[spoiler: Dickson]] has [[KickTheDog kicked the dog]] so many times the player is likely to want to kill him.
* ''[[VideoGame/TimeCrisis Time Crisis 5]]'' has [[spoiler: the sword fight between Keith and Robert.]]
* ''[[VideoGame/ProjectXZone Project X Zone 2]]'' has any of the boss fights involving [[VideoGame/StarGladiator Black Hayato]].
* All the battles with Estina in ''VideoGame/{{Astebreed}}'' qualify.
* ''Franchise/AceAttorney'' doesn't have actual "fights", but your goal as a defense attorney is to bring out the truth by finding contradictions in the witnesses' testimony, figuratively fighting them as well as the prosecutors who actively oppose you. Notable examples are below:
** In ''Trials and Tribulations'', [[spoiler:''Maya herself'' is one of the de facto final bosses by being the game's final witness to cross-examine, alongside Godot (the killer) who she tries to defend because he was once her sister's boyfriend.]]
** ''Apollo Justice'' has Kristoph Gavin, who is Apollo's mentor as a defense attorney. Apollo's first case snowballs when Phoenix Wright accuses Kristoph for murdering the victim and Apollo sides with Phoenix to find the truth. You then cross-examine Kristoph and prove he's the killer. [[spoiler:Kristoph returns as the final witness in the final case, despite already being charged with murder from the first case, and you have to cross-examine him again to prove he poisoned a young girl as well as giving Phoenix forged evidence, which got him disbarred from law.]]
** In the first half of the final case in ''Dual Destinies'', [[spoiler: Apollo testifies against Athena, where the latter is accused of murdering her mother many years ago. The turn of events forces Phoenix to cross examine Apollo to discredit his testimony. It turns out that Apollo testified because he ''wanted'' to be proven wrong due to his lie detecting bracelet going off whenever anyone talked to Athena about his mother and he didn't want to believe she was the killer. It turns out that she never committed the crime and just had traumatic and fuzzy memories of the event.]]
** ''Spirit of Justice'' has a double whammy in the final case for Apollo. [[spoiler:Phoenix agrees to help a client who is claiming that the Founder's Orb belongs to him while Apollo goes against him and claims the orb belongs to Dhurke. Apollo and Phoenix face each other in court in a civil case and even the judge is surprised to see the two attorneys go against each other. Phoenix pulls no punches and Apollo doesn't hold back either, but as the trial goes on, Apollo notices Phoenix is acting more odd and even becomes desperate to defend his client (he usually is in any normal case, but he comes up with ''even sillier'' arguments than usual). It turns out Phoenix was being blackmailed by his client because Maya was kidnapped by someone affiliated to the client. In the last stretch of the case, Apollo's friend, Nahyuta, testifies against himself by admitting that he killed Dhurke. However, Nahyuta is only taking the heat so that his mother and sister aren't put in danger by the evil Queen that is behind the country's ridiculous laws.]]
* In ''VideoGame/{{Undertale}}'', before you leave the Ruins, Toriel, whose previous interactions with you have been overwhelmingly friendly, insists on fighting you in the first BossBattle to prove yourself "strong enough to survive" outside. Unlike many examples of this trope, it's possible to actually kill Toriel by fighting her, and the game springs this PlayerPunch all too readily on unwary players by letting them land a killing blow with her LifeMeter only about half empty, in case you were going for the "Bring them to near death" option of sparing monsters.
** For the TrueFinalBoss of the [[PacifistRun True Pacifist Run]], [[spoiler: once you unlock the "Save" option, you have to fight all of the main characters you befriended, who have been reverted to their pre-CharacterDevelopment mindsets. (i.e. Toriel doesn't want to let you leave, Asgore thinks he ''has'' to kill you, Alphys thinks everyone hates her, etc.) To do this, you have to [[IKnowYouAreInThereSomewhereFight ACT in ways that remind them of the times you've spent together]], while [[FinalExamBoss dodging the same attacks as they used the first time you fought them.]] (Apart from Alphys, who otherwise isn't fought and instead uses Mettaton's attacks, and Sans, who is only fightable on [[KillEmAll the exact opposite path]] and instead uses Papyrus's attacks.)]] If you subscribe to the theory that the narrator is actually [[spoiler:the first Fallen Child]], this battle also counts for them since the final boss is [[spoiler:Asriel, their best friend when they were both alive]].
* In ''VideoGame/SouthParkTheStickOfTruth'', all six of your buddies are potentially fought as bosses. Jimmy is fought late on the first day; on the second day, depending on who you side with you either fight Stan then Kyle or Butters then Cartman; Kenny [[spoiler:is the game's FinalBoss and must always be fought]].
* Happens again in ''VideoGame/SouthParkTheFracturedButWhole''. Among the playable characters, Kenny, Stan, Token, and Tweek are fought during the civil war segments; Butters is fought as the DiscOneFinalBoss and pulls a HeelFaceTurn shortly afterwards; Cartman, Kyle, Clyde, Craig, Jimmy, and Scott are all brainwashed by Professor Timmy and forced to act as his minions during the final fight with him; and [[spoiler:the New Kid is fought in their King Douchebag persona when the party travels back in time to stop the BigBad's evil plans]]. The only playable character to avert this outright is Wendy.
* This happens in at least one ending in every game in the ''Franchise/{{Drakengard}}'' series.
** ''VideoGame/{{Drakengard}} 1'' has ending B ([[spoiler:Caim vs. Furiae]]) and ending C ([[spoiler:Caim vs. Angelus]]).
** ''Drakengard 2'' has this in every ending. Endings A and C have [[spoiler:Nowe vs. Legna]], notable for being the only instance in the series to occur as a result of a genuine ideological fallout instead of some variant of DemonicPossession. Ending B has [[spoiler:Nowe vs. Manah]].
** ''VideoGame/Drakengard3'' has ending D ([[spoiler:Mikhail vs. Zero]]).
** ''VideoGame/NieR'' has endings C and D ([[spoiler:Nier vs. Kaine]]).
** ''VideoGame/NierAutomata'' has this late in the C/D route, where [[spoiler:9S has to fight several 2B units which use his memories of her to full effect.]]

!!Non-video game examples:

[[folder: Anime and Manga ]]

* ''Anime/StreetFighterIITheAnimatedMovie'': Moments before the battle with [[BigBad M. Bison]], Ryu is forced to face his best friend and sparring partner, [[BrainwashedAndCrazy Ken, who'd been enslaved]] by Bison's Psycho Power. Rather than fight him, [[IKnowYoureInThereSomewhereFight Ryu tries getting through to him instead]], by trying to remind Ken of who he was, and their friendship - all while being relentlessly attacked. Ryu succeeds without throwing a single punch.
* ''Anime/VariableGeo'': Yuka ends up having to face her ChildhoodFriend and rival, Satomi, [[IKnowYoureInThereSomewhereFight to free her]] from [[spoiler: [[BigBad Miranda]]]]'s control. Afterward, Yuka and Satomi turn [[KameHameHadoken their combined might]] against [[SoulJar the cyber drive]], taking [[spoiler: Miranda]] with it.
* ''Anime/RuneSoldierLouie'': [[AmazonianBeauty Jeanie]] and [[BoisterousBruiser Louie]] finally come to blows near the end of episode 12, when her patience with him runs out. She assumed he had come back for her because she was a woman, [[ItsPersonal which struck a nerve]], since it reminded her of the time [[spoiler: her former comrade, [[HeroicSacrifice Hector, sacrificed himself]] by staying behind, so she wouldn't have to die]] (seen [[http://www.youtube.com/watch?v=eh5Ex0SOf0E at 13:23-16:57, here).]]
* The second ''Anime/FutariWaPrettyCureMaxHeart'' movie has baddies Freezen and Frozen do this towards both Cure Black and Cure White when the two heroines confront them. Cure White is brainwashed first and when Cure Black refuses to fight back, they brainwash her as well. Cure White frees herself from the hold first and it takes until the two nearly plunge to their deaths that Cure Black is freed. It shakens them badly, but they use it to reaffirm their friendship once they're both free.
* In ''Anime/SenkiZesshouSymphogear G'', this happens in the episodes 10 to 12. [[spoiler:First, [[BadassGay Miku]] is BrainwashedAndCrazy and equipped with the Symphogear Shenshou Jing and attacks Chris and Tsubasa. Hibiki, who is the main motivation of Miku's power, fights her and manages to bring her back by destroying Shenshou Jing with its AntiMagic power, while sacrificing her own Symphogear Gungnir (which by the way was about to kill Hibiki in few days, anyway). Then there are two pair of friends who are fighting each other simultaneously. FakeDefector Chris fights Tsubasa, the latter manages to destroy the ExplosiveLeash on Chris' neck. And Shirabe, who goes a HeelFaceTurn, fights Kirika, who nearly kills Shirabe and has also a HeelFaceTurn after their fight.]]
* A common thing in ''Franchise/YuGiOh''. Since friendship is one of the main themes, there will always be a point where the protagonist will duel a BrainwashedAndCrazy friend, mostly his best friend.
* ''Manga/YuGiOh'':
** Before Yugi can duel Pegasus, he has to defeat Jonouchi in the final first.
** The famous "anchor duel" between Yugi and the BrainwashedAndCrazy Jonouchi. Both of them are chained to an anchor that will drag at least one of them into the sea if the time limit is over. Between the feet of a duelist is little box that contains the key of his shackle, and reducing the Life Points of the opponent to 0 will open the box. Malik is smart enough to use different keys for the boxes, so saving attempts will become useless. Yugi successfully de-brainwashes Jonouchi by constantly reminding him of their friendship, and Jonouchi manages to end this duel in a draw, so both keys can be unlocked. Jonouchi saves Yugi in the sea, while Jonouchi is saved by either his little sister Shizuka (anime) or Kaiba (manga).
** In the Doma arc, Atem is forced duel Yugi, whose soul was stolen by the Seal of Orichalcos.
** Also, in the Doma arc, Jonouchi duels an {{Face Heel Turn}}ed Mai twice. He loses his soul in the second duel, but Mai comes back to her sense.
** The final duel is between Atem and the Yugi. Yugi must defeat Atem, so the latter can leave the word of the livings or he is "trapped" in this world.
* In the third trial of ''Anime/YuGiOhCapsuleMonsters'', Yugi is forced to do this with Jonouchi when the latter is possessed by the Blade of Chaos, though Yugi isn't too happy about it.
* Because brainwashing or possessing people happens a lot in ''Anime/YuGiOhGX'', Judai is often forced to duel his friends and then turns them back to his side.
** Judai duels an evil Manjoume twice, once when he is brainwashed, and later when he is "zombiefied".
** Judai duels Asuka when she is brainwashed like Manjoume.
** In a twist, after Judai turns evil, he duels Jim and O'Brien to death. Jim fails to bring Judai back to his senses, but O'Brien succeeds to snap Judai out of it since the result is a draw.
** Judai duels a possessed Johan, his second best friend, and one of the reasons why Judai turned evil before.
** In the fourth season, Judai duels Fubuki, who uses the power of [[BigBad Darkness]], so Fubuki will retain his lost memories.
** Also in the fourth season, Judai duels Saiou, who is not consumed by the Light of Destruction this time, but Saiou tries to save the soul of his sister Mizuchi.
* In ''Anime/YuGiOh5Ds'', Yusei has a bad luck regarding dueling his best friends.
** Before the start of the series, Yusei was betrayed by his best friend Jack, who stole his D-Wheel and Stardust Dragon to become the King of Riding Duels in New Domino City and leaving the slums of Satellite, becoming Yusei's rival. Even so, Yusei still views him as his friend and their friendship returns after Jack loses to him in the Fortune Cup.
** Yusei learns in a hard way that his best friends Kiryu and Bruno turn out to be his enemies, the former was believed to be dead. After defeating them, they died, which incredibly saddens Yusei, who makes a SkywardScream (SayMyName) both times. Though, Kiryu gets better. Bruno not so much.
*** In Bruno's case, even though he turns out to be an enemy, he is still Yusei's friend at the same time during their duel. He tries to prepare Yusei for the final duel against [[BigBad Z-One]] and shows him a new Synchro Summoning method that Yusei should surpass. After the duel, Bruno even sacrifices his life to save Yusei from the black hole.
** If ExecutiveMeddling didn't happen, Yusei would duel his other best friend Crow, who was originally planned to be the FinalBoss of the Dark Signer arc.
** Jack duels his evil-turned LoveInterest Carly who like Kiryu dies after Jack's victory. Like Kiryu, she gets better.
** The final duel is between Yusei and Jack, which is a friendly duel this time. This duel gives Yusei the answer which path he wants to go in the future, and it also inspires Aki, Crow, Luca and Lua to choose their path.
* ''Anime/YuGiOhArcV'': To qualify for the Maiami Championship, Yuya needs to defeat Gongenzaka to get a 60% victory ratio. Gongenzaka himself risks his own qualification to have a serious duel with Yuya. Fortunately, Gongenzaka still manages to get a 60% victory ratio later on.
* In Episode 7 of ''Anime/KillLaKill'', Ryuko is forced to fight Mako after Mako and her family becomes corrupt by greed and Mako becomes Fight Club President when Ryuko wants to disband. In addition, Mako gets her own Two-Star Goku Uniform.


[[folder: Comic Books ]]

* Some examples from ''ComicBook/{{Supergirl}}'' stories:
** In ''ComicBook/RedDaughterOfKrypton'', Silver Banshee has to fight her friend Kara, who is out of her mind due to the influence of a [[Franchise/GreenLantern rage-fueling Red Power Ring]].
** In ''ComicBook/ManyHappyReturns'', Linda knocks her friend Kara out in order to take her back to her timeline.
** In ''ComicBook/TheSupergirlFromKrypton'', Franchise/{{Superman}} faces off against his brainwashed cousin. He doesn't want to fight Kara, but when she almost kills him he forces himself to use Kryptonite to knock her out.
* In ''Franchise/{{Superman}}'' story ''ComicBook/WarWorld'', villain Mongul blackmails the Man of Steel into stealing a key protected by his buddy Justice Leaguer ComicBook/MartianManhunter. Kal-El manages to defeat J'onn, but feels awful about it.


[[folder: Fan Works ]]

* The TwistEnding of the [[WhatCouldHaveBeen unmade]] ''Fanfic/CalvinAndHobbesTheSeries'' episode "Cowpokes" would have been that [[spoiler:Calvin (the sheriff) and Hobbes (the desperado)]] would have to duel each other.
* A rare EvilVsEvil and VillainousFriendship example in ''Fanfic/TheBridge''. [[NobleDemon Monster X]] starts turning into his berserk alternate form, [[ChaoticEvil Kaizer Ghidorah]]; forcing his friend [[LawfulEvil Gigan]] to desperately try and get through to him [[IKnowYoureInThereSomewhereFight mid-conflict]].


[[folder: Film ]]

* In ''Disney/TheFoxAndTheHound'', Copper and Tod end up fighting one another at the climax, Copper being turned against his old friend by his owner.
* In ''Film/CaptainAmericaTheWinterSoldier'', this is how Steve sees fighting the titular villain. The sentiment does not seem mutual, [[spoiler:at first.]]
* One-sided in ''Film/ThorRagnarok'': Having been captured by the Grandmaster, Thor is willing to fight the champion for his freedom... [[https://www.youtube.com/watch?v=jFPBQaPL5mQ and then sees who this champion is.]] [[spoiler:The Hulk]] doesn't see him as a friend, however, [[LetsYouAndHimFight and they fight as expected.]]
* Like in ''VideoGame/ResidentEvil5'', Alice fighting [[spoiler: a BrainwashedAndCrazy Jill Valentine]] in ''Film/ResidentEvilRetribution'' is this.
* The fight between Nada and Frank in ''Film/TheyLive''
* The main conflict in ''Film/CaptainAmericaCivilWar'' is between Captain America and Iron Man.


[[folder: Live Action TV ]]

* ''Series/TheFlash2014'' has done this twice. In [[Recap/TheFlash2014S1E8FlashVsArrow "Flash vs. Arrow"]], [[Comicbook/TheFlash Barry]] is affected by a HatePlague, forcing [[Comicbook/GreenArrow Oliver]], the Series/{{Arrow}}, to take him down. In [[Recap/TheFlash2014S3E7KillerFrost "Killer Frost"]], both Barry and Cisco have to fight the titular villain, who is [[spoiler: Caitlin, having been taken over by her SuperPoweredEvilSide]].


[[folder: Professional Wrestling ]]

* [[Wrestling/DevonStorm Crowbar]] and Wrestling/DaffneyUnger held back when they had to fight one another for the Wrestling/{{WCW}} Cruiserweight Championship. The ending came when Daffney pinned him on accident!
* Wrestling/JimmyJacobs purposefully made [[Wrestling/HunterJohnston Delirious]] go through this twice, first turning him against Wrestling/DaizeeHaze and then sending Wrestling/MsChif against him when that turned out not work in the long run. Through mind games Jimmy also turned Ta'Darius against ACH.
* Wrestling/{{Christian}} said as much in Wrestling/{{WWE|}}[[Wrestling/{{ECW}} CW]] when he had to defend the ECW championship against Wrestling/TommyDreamer. He found it refreshing to actually put the belt up against someone he liked.
* Niche found himself doing this at the end of the WWC Euphoria tour when he was being managed by Wrestling/BlackRose but his partner Lynx no longer was and she attacked Lynx, ordering Niche to join her. Niche didn't like it and eventually he and Lynx reunited as Los Fugitivos de la Calle.
* As Wrestling/{{TNA}}'s director of wrestling operations, this became Wrestling/{{M|ontel Vontavious Porter}}VP's default method of dealing with wrestlers who repeatedly questioned his authority, with the threat of being fired to violators (though none of them ever were). The American Wolves Davey Richards and Eddie Edwards were first, Wrestling/SamoaJoe and Wrestling/AustinAries also.


[[folder: Roleplay ]]

* ''Roleplay/DestroyTheGodmodder'': When Minor attempted to boost his own power, the godmodder instead manipulated the attempt into turning minor into his own minion. Minor became the biggest threat on the field up until his defeat.


[[folder: Visual Novels ]]

* ''VisualNovel/FateStayNight'', Heaven's Feel route. Shirou vs. [[spoiler:[[SuperpoweredEvilSide Saber Alter]].]] Made worse by the fact that to play Heaven's Feel, you have to have played the Fate route in which [[spoiler: Saber is Shirou's main {{Love Interest|s}}.]]


[[folder: Web Animation ]]

* The ''WebAnimation/{{TOME}}'' 5-year anniversary short features [[spoiler: Alpha fighting Zetto, who has at this point been revealed to actually be Kirbopher's alter ego. Since the Kirbopher character model was destroyed, Michael and Christopher hang out in the game using Chris's Zetto character model instead, and as such are able to have friendly battles without having to worry about any of the serious events that usually took place whenever Christopher was logged on as Zetto. Although since Kirbopher is really Zetto, technically any fight that took place between Alpha and Zetto in the past could be considered this, albeit unknowingly.]]

[[folder: Western Animation ]]

* In the original ''WesternAnimation/{{ThunderCats|1985}}'', Lion-O had to do this for most of the five-part "The Anointment of Lion-O" story. (Usually, the trials that the Lord of the Thundercats has to go through in this ComingOfAge ritual wouldn't be administered by his friends, but seeing as they were the [[LastOfHisKind Last of Their Kind]] - that they knew about at the time - it was the only option.) Fortunately, his foe in the final and most important trial of the ritual wasn't a friend at all - it was [[BigBad Mumm-Ra]].
* One match during fan-vote episode of ''WesternAnimation/CelebrityDeathmatch'' pitted Adam Sandler and Chris Rock against one another, both of whom had no desire to fight to the death because they were close friends. It wasn't until referee Mills Lane started lowering a giant DeadlyRotaryFan on them under the guise that it would only stop once one of them is dead, did the two decided to begrudgingly try and kill one another. There are many other matches of two "friends" fighting, but typically its explained that they had some sort of heated argument or they are just alright with knocking out their business competition so this trope isn't usually invoked otherwise.


[[folder: Other ]]

* In Creator/AdamSandler's The Champion, the Champion tackled [[BlackBestFriend Skipper Jenkins]] and the other way around before the Champion can finish the 18th golf hole.
-->'''Skipper Jenkins''': That's it! I'm getting the fuck out of here! You fucked up, dude! You need some serious help!
-->'''The Champion''': And I need help fucking your wife!
-->'''Skipper Jenkins''': FUCK YOU! Don't you ever talk about my wife! [[IllKillYou I'll fucking kill you, man]]!