Involuntary Battle to the Death

"Melllvar: To prove who is more worthy of my fanatical devotion, I shall pit you against each other in armed combat... to the death! Bender: Where did you get an idiotic idea like that? Melllvar: Episodes 19, 46, 56, and 77."

- Futurama, Where No Fan Has Gone Before

Two parties are placed in a situation where one of them has to kill the other, usually in a contest of some kind. If they refuse or come to a stalemate, both die. Almost always initiated by a third party, usually a sadistic bastard. The catch is that neither side wants to kill the other, sometimes creating a "take me instead" type situation. Most of the time the contest is stopped when a fourth party or the participants Take a Third Option.

Note that for a situation to be an example of this trope, the participants have to be people who would not kill each other in a normal situation. So Combat by Champion would not count unless the champions were actually best friends and were unable to back down.

Closely related to the Sadistic Choice and often used in conjunction with Villain Exit Stage Left. Sometimes occurs in There Can Be Only One plots.

Subtropes are:
 * Blood Sport
 * Deadly Game
 * Deadly Graduation
 * Duel to the Death (some instances)
 * Finish Him!
 * Forced Prize Fight
 * Gladiator Games

Contrast Shoot Your Mate.

Anime and Manga

 * At one point in Bokurano, it is revealed that Each of the sides are fighting
 * During the Battle City arc of Yu-Gi-Oh!!, Marik mind-controls Joey, and forces him and Yugi into a duel. Both are attached to chains attached to an anchor; winner gets the key to his shackles, loser takes a plunge into the ocean. Oh, and Tea's tied to a chair with a large crate over her head, so no one can interfere. It would have worked except for the fact that it was escapable.
 * The fight between the Space Angels and Guntroll during the Z.O.T. Tournament in Gunnm: Last Order. Both groups had absolutely no reason to fight each other if not for the tournament, and were indeed pretty friendly towards each other, but both had to win for various reasons. Well, at least from Gally's point of view, and she was suffering the existential crisis at the time. Sechs was an Idiot Hero whose only meaning of life was fighting, and twins were just too airheaded to care. So they've fought and much awesomeness ensued.
 * Jigen and Goemon get into this situation in the Lupin III special "The Mystery of the Hemingway Papers". During their first confrontation, they're able to fake a convincing stalemate, but when they face off a second time, both are aware that it won't work again.

Comic Books

 * Villains love to do this with Modesty Blaise and Willie Garvin.

Fan Works

 * Used in the Tron: Legacy fanfic "A Survivor's Tale." Yori, who's been working with the Resistance, is captured and sent to the Games. Unfortunately, she has to face off against you know who...Turns into an Awesome Moment, though, when she's able to battle him to a draw.

Film
"Herod: If neither one of you fire by the time I count down from ten, my men will gun you down. Ten... nine... Cort: Draw your gun. He'll do it. Herod: Eight. Seven. Cort: Draw! Herod: Six. Cort: Kill me, Ellen. Herod: Five. Cort: Kill me! Kill me! Kill me. Or I'm gonna kill you. Herod: One! *Cort finally shoots and down goes the Lady* Doctor: *runs over to Ellen* She's dead. She's dead! Leave her alone. You vultures. Don't touch her! Herod: Nice shooting, Reverend. You put a fox in the henhouse and he'll have chicken for dinner.
 * Balls of Fury: The hero and his love interest are forced to fight each other in ping-pong, loser dies. Each tries to make the other win, but the contest is stopped halfway for being boring.
 * In The Dark Knight, the Joker has rigged two boats with explosives, and given each boat the denotator to the other. If one boat blows up before midnight, the other is spared. If not, Joker blows them both up. Plenty of fans have guessed the the Joker was lying about which explosives the denotators would trigger.
 * Earlier, when Joker kills Gambol, he turns to the crime boss's men and tells them he's hiring, but there's only one spot. He then drops a broken pool cue between them...
 * The boat thing is also complicated by the fact that one is filled with ordinary people, while the other is filled with convicts.
 * In Spartacus Spartacus and one of his soldiers are made to fight to the death. However the one who wins will be crucified, so while they are friends, they're genuinely trying to kill each other because it's cleaner than crucifixion. One wonders why they gave him the satisfaction instead of just running each other through, or falling on their swords.
 * No Escape: Marek sets Robbins against
 * History of the World Part I by Mel Brooks. Brooks's character (Comicus, a comedian) and a slave he rescued earlier, Josephus, end up in one of these.
 * The Quick and the Dead: Almost played straight, but they wind up taking a third option. Forced into a shootoff. Crowe's charcter, Cort, is forced into practically every shootoff, but especially the one with Ellen (The Lady). Neither wants to shoot the other. Both want to shoot Herod, though.

Fortunately,"


 * The Barbarians features two imprisoned twin brothers, who are raised to hate an opponent wearing a special helmet. They're pitted against each other in gladiatorial combat wearing said helmets. When the masks come off, they recognize each other, and refuse to fight.

Literature

 * In A Song of Ice and Fire, trial by combat is a common way to end matters that can't be resolved in any other way, but Joffrey Baratheon enjoys forcing them on people for minor disputes.
 * Fredric Brown's short story "Arena".
 * In Dark Lord of Derkholm, Blade and Kit (who are brothers despite being, respectively, a human and a griffin) are both forced to compete in Gladiator Games and unexpectedly encounter each other as opponents. They stage a fight until they can figure out how to escape.
 * This sort of thing happens rather frequently in the Barsoom novels. In A Princess of Mars, leads to a very cool moment where Carter and Kantos Kan escape by fighting for hours (until sunset), then faking the death of one of them whilst the other one is set free for winning.
 * The entire plot of The Hunger Games may be seen as this, with 24 teenagers chosen at random for a survival and fighting competition to the death. However, the author finds a way to keep from killing all the people we know.
 * Similarly to the above example, the central premise of Battle Royale is a class of ninth graders thrown into an Involuntary Battle To The Death on a deserted island.
 * toyed with in the ten tennis shoes adventure book, where two characters are recruited to fight in a gladiatorial match, by opposing teams. neither knows the other is their opponent, and after the two leaders tell the characters that the other killed their girlfriend/ friends, they are willing to fight- but when they figure out who the other is, they stop.

Live Action TV

 * Star Trek the Original Series episodes "Arena" and "The Gamesters of Triskelion".
 * "Amok Time" as well, kind of.
 * "Day of the Dove" and, of course, "Bread and Circuses". And kind of in "The Omega Glory". And don't forget "The Savage Curtain". TOS was absolutely in love with this one!
 * The Outer Limits TOS episode "Fun and Games".
 * An unusual use came in the first season of Blackadder, when Edmund challenges a notorious warrior to a duel for calling him a bastard (parentally speaking). He rather loses momentum when the man enthusiastically replies ''TO THE DEATH!", but can't back out by that point.
 * The MO of the murderer in the Criminal Minds episode "The Fight".
 * Power Rangers Lost Galaxy: Deviot outfits the Blue and Green Rangers with mind-controlling shackles, forcing them to fight each other so he can harness the energy they expend. They probably would have died from exhaustion had the other Rangers not staged a rescue.
 * Happens in the Merlin episode "The Coming of Arthur: Part One" between Arthur and . It was mostly a coincidence, as the instigator of the fight had no idea that the two men had ever even seen one another before.
 * In The Sight the villain forces Huttser and Palla into one of these by threatening to kill the survivor painfully, causing them to each struggle to give the other a merciful death.
 * In the MacGyver episode "Humanity", Mac is captured in Romania by a member of the K-Force, a Praetorian Guard still loyal to Romania's dead tyrant Ceauşescu. After seeing Mac fishing, he becomes upset and later reveals that the K-Force's Training From Hell (which begins in early childhood) forbids any sort of friendship. When he and another kid he had befriended went fishing with some rods stolen from the base, they were caught and forced to have a knife fight to the death. Naturally, he won but he still feels guilty to this day.

Video Games

 * Midway through Neverwinter Nights 2, The Laws of Neverwinter force you to face and kill Lorne in single combat. You may wish to spare him but the law does not allow it. Death by Irony for Lorne, who committed the murders you were on trial for.
 * In the climax of Army of Two: The 40th Day, Big Bad Jonah threatens to destroy the city with a nuke unless one of the heroes shoots the other to prove their willingness to sacrifice for the greater good. There is no third option. If you're playing Co-Op, the first player to reach the trigger gets to make the decision on whether to shoot Jonah (and thus trigger the countdown on the nuke, dooming the city but giving you two time to escape together), or to shoot their buddy and save the city.
 * Splinter Cell: Conviction
 * Silent Scope 2: The Big Bad forces the two protagonists to fight each other in a sniping duel, with the winner taking the Damsel in Distress.
 * Jak 3: Early in the game, Jak and Daxter are put through a series of gladiatorial trials to earn citizenship in Spargus City. They are quite surprised to come up against their old friend Sig at the last minute, in an arena whose only rule is "kill or be killed."
 * A conversation with SIGINT in "Metal Gear Solid 3 Snake Eater" implies that The Boss  in a similar situation, but it isn't until "Metal Gear Solid: Peace Walker" that EVA tells Big Boss the truth, that
 * The main premise of Chaos Rings and Chaos Rings Omega is an involuntary tournament to the death: five couples are chosen, and must combat each other until only one is left.

Web Comics

 * Domain Tnemrot features this. Legally, slaves registered as battlers have to fight once a week or they are recalled, since high mortality rates means they're in too much demand to be kept from the ring.
 * 'It's like watching someone duel their own puppy.'

Web Original
"129. Despite the delicious irony, I will not force two heroes to fight each other in the arena."
 * The Evil Overlord List, not surprisingly, cautions against this.

""God, how messed up is that? Escape's not even the top of my list!""
 * Discussed by Kevin Smith and Scott Mosier in their weekly podcast SModcast, in the guise of being forced to fight each other, in a post apocalyptic world by vampire kings: Smith is so sure that he'd die that he offers himself as a sex slave, instead.

Western Animation

 * Futurama spoofed this, along with other Star Trek tropes in "Where No Fan Has Gone Before". Powerful Energy Being (and raging Fan Boy) Melllvar pits the Planet Express crew against the cast of Star Trek the Original Series in a battle to see which is more worthy of his devotion.
 * Impressive list. But you forgot about episode 18! As in, "Why Must I Be a Crustacean in Love?," when Fry and Zoidberg get into a "Claw-Pla'q," although it is only involuntary on one end.
 * Avatar: The Last Airbender uses this, too, when Hama forces Aaang and Sokka into one - which Katara has to stop, naturally, leading her to learning blood-bending.