->''"Have you been keeping well? Thank you for [[TheClimax 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.'''

----
!!Examples
* 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.
** [[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 alright, 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.
* ''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.
* 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 one game before that, Zero is forced to fight Iris. [[ILetGwenStacyDie We all know how that went]].
** ''VideoGame/MegaManStarForce'' also does this, as 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.
* ''Franchise/{{Castlevania}}'':
** Julius Belmont in ''[[VideoGame/CastlevaniaChroniclesOfSorrow Aria of Sorrow]]''.
** Trevor Belmont in ''VideoGame/CastlevaniaCurseOfDarkness'' too.
** [[BrainwashedAndCrazy Richter Belmont]] in ''[[VideoGame/CastlevaniaSymphonyOfTheNight Symphony of the Night]]''.
** [[RivalTurnedEvil Hugh Baldwin]] in ''[[VideoGame/CastlevaniaCircleOfTheMoon Circle of the Moon]]''.
* 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 yourself with the templars.
** In the sequel, 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 Atlus's ''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 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}}]], ''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 ''Franchise/YuGiOh: Nightmare Troubadour'', 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 ''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.
* The [[SuperNintendoEntertainmentSystem Super Famicom]] game ''TenchiMuyo Game Hen'' has everyone's favorite SpacePirate Ryoko Hakubi as a late-game boss, following her [[DistressedDamsel 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 [[FlunkyBoss flunkies]].
* ''VideoGame/{{Xenogears}}'' uses this trope several times too. There's only three party members you don't fight at some point in the story.
* ''AdvanceWars: Dual Strike'' features a [[UnfortunateImplications disturbing]] version of this, in which potential allies pit their armies against yours in order to test your skills as a commander. If you follow the story from the perspective that the game's units represent actual human soldiers, it's actually rather horrifying.
** 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.
** Arguably, 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 ''{{Enter the Matrix}}'' are like this. The former is a sparring match between friends. In the latter case... he fights EVERYONE he meets with, apparently.
* 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.]]
* Happens in every Franchise/TalesSeries game, actually, with the exception of VideoGame/TalesOfEternia and VideoGame/TalesOfPhantasia. Oftentimes it gives a nice battle?
** Unless you count fighting the Summon Spirits.
*** Which is DefeatMeansFriendship.
** Well, ''VideoGame/TalesOfEternia'' does pit 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.
** ''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.
* Depending on the team you choose in ''VideoGame/{{Touhou}} Imperishable Night'', stage four will have you pitted against Reimu or Marisa. This is also where the difficulty level of the game [[ThatOneBoss spikes dramatically]].
** This also happened earlier in the series, in ''Lotus Land Story'', with Reimu and Marisa being pitted against each other in the fourth stage.
** In ''Ten Desires'', the Stage 1 boss is [[spoiler:Yuyuko, the FinalBoss of ''Perfect Cherry Blossom'']], who here is just helping out the heroines and holding back her power to serve as a WarmupBoss.
* The third stage of ''MagicalBattleArena'' has your character finding her respective ally ([[MagicalGirlLyricalNanoha Nanoha and Fate]], [[OriginalGeneration Sarara and Kirara]], [[{{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 [[MahoujinGuruguru 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.
* A variant occurs in ''VideoGame/PaperMarioTheThousandYearDoor''. One boss fight has you fighting a traditional boss but your allies are fighting alongside him.
** Also, Mario is forced to fight [[spoiler:a possessed Princess Peach, who is now the Shadow Queen.]]
* 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 ''PhantomHourglass'', in which the final boss is actually [[spoiler:your buddy Linebeck possessed by Bellum]].
* In ''[[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".
* ''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.
* ''{{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 one of the ''MetalSlug'' games, 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.
** That was Metal Slug 6. 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 GreatMazinger (piloted by Blacki) and MazingerZ piloted by a brainwashed Kouji Kabuto. Eventually, he breaks Kouji free and defeats GreatMazinger with his help.
* [[spoiler:Pixy]] is fought twice in {{AceCombatZero.}}
* ''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 ''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 MetroidPrime 3 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 Beyond Good & Evil, 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 ''{{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}} Pokémon]] [[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 [[CareBears Care Bear]].
** 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'': [[BigBad Bison]] abducts Ryu and [[BrainwashedAndCrazy injects him with a portion of his Psycho Power]], forcing ''[[TheRival Sagat]]'' [[IKnowYouAreInThereSomewhereFight 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.
* ''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}}.]]
* ''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.]]
* 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.
* 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}} killed off for real]], 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 Raiou and his best friend, Jowy, which gets briefly postponed when [[spoiler: Gordo's]] men mortally wound [[spoiler: Raiou's adopted sister, Nanami]]. In the end, if Raiou 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 Franchise/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.

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!!Non-video game examples:
[[foldercontrol]]

[[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'': Much like the preceding example, 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.
* 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, who 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.]]

[[/folder]]

[[folder: Comic Books ]]

* ''ComicBook/BatmanTheDarkKnightReturns'': Franchise/{{Batman}} vs. Franchise/{{Superman}}.

[[/folder]]

[[folder: Fan Fic ]]

* 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.

[[/folder]]

[[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.]]

[[/folder]]

[[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 WWECW 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 stopped fighting Lynx to reform Los Fugitivos de la Calle.
* As 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]]

[[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]]

[[folder: Western Animation ]]

* In the original ''Main/{{Thundercats}}'', 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]].

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