Two forces exist within the same 'verse. Both of them are unbreakable absolutes. And they are diametric opposites.
Naturally, this raises one question in everyone's mind: What happens when they fight? Sometimes the story itself will depict the fight, sometimes characters will simply speculate about the fight, and sometimes the story won't address the issue at all, leaving the fans to debate amongst themselves what the outcome would be.
There are several possible outcomes:
- One or both of these forces proves less absolute than advertised:
- Yin is stronger and defeats Yang (or vice-versa).
- Yin and yang both destroy each other simultaneously, an outcome that's both a win and a loss for both sides.
- The two forces are completely evenly matched, so they clash forever or until some outside force intervenes.
- Both of the forces are absolute, so the logical contradiction of their fight destroys the universe.
In the West, the Unstoppable Force Meets Immovable Object conundrum is the most famous version of this, enough so that it's become a Stock Phrase. The Eastern equivalent is the unstoppable sword and unbreakable shield (see Folklore, below)—the Chinese word for "contradiction" is derived from this.
Please note: This is for actual, absolute forces. See Unstoppable Force Meets Immovable Object for the use of that particular stock phrase to refer to objects or people who aren't absolutes.
Compare Balance Between Good and Evil and Light/Darkness Juxtaposition, which may be represented with this. If the two characters are not life and death personified as absolutes but have these as motifs anyway, that's Life/Death Juxtaposition. Contrast Yin-Yang Bomb when someone sniffs at the idea of opposing yin-yang sides and points out that the two actually complement each other in a powerful way.
- According to Go Nagai (making it half Word of God, half Word of Saint Paul), Shin Getter and Mazinkaiser are equals, Shin Getter possessing the ultimate offensive power, and Mazinkaiser possessing the ultimate defense. When they appear in crossovers like Super Robot Wars, it's popular to have them fight each other or at least show up around the same time.
- In Katanagatari, two of the Twelve Deviant Blades are a sword that is supposedly unbreakable and a sword that supposedly can cut through anything. Shichika briefly wonders what would happen if the swords clashed. Togame guesses that the sword that can cut through anything would defeat the other since it was a later creation of the Ultimate Blacksmith who forged all of the Deviant Blades and thus was forged with greater skill and knowledge. This foreshadows the end of the series, when Shichika, whose fighting style and bloodline are the thirteenth Deviant Blade, easily shatters the "unbreakable" sword.
- In High School DXD, this is the relationship between Boosted Gear and Divine Dividing. Issei's Boosted Gear doubles his power every ten seconds, while Vali's Divine Dividing halves its opponent's power every ten seconds, resulting in a zero sum game. This stalemate is broken the first time when Issei incorporates a fragment of Divine Dividing into his Boosted Gear armor, by conscious abusing the fact he doesn't understand how utterly impossible it should be, giving him an arm that can punch Vali and nullify Divine Dividing's effect.
- A Certain Magical Index: Touma Kamijou's Imagine Breaker ability, housed in his right hand, represents the hope to change the world back to normal. As a result, it is a powerful Anti-Magic and Power Nullifier that even works on Reality Warper powers. Kakeru Kamisato's World Rejecter ability, also housed in his right hand and specifically stated to be Imagine Breaker's opposite, represents the hope to escape the current world. As a result, it has the power to create new worlds and exile anyone and anything into them. When the two fight, Touma's hand gets ripped off and exiled to another world, but the "Invisible Thing" sealed within Touma emerges and injures Kakeru, forcing him to retreat as Touma's hand regenerates.
- In Dragon Ball Super, Zen'o is the Top God of the Dragon Ball multiverse. He has the power to erase absolutely anything from existence entirely. It is also stated that his existence is absolute, and he will always exist no matter what. It is unknown if he can erase himself. He also has an Alternate Self from an alternate timeline who is his equal in power. It is unknown if they can erase each other, not that they're likely to try. Additionally, the Super Dragon Balls can grant absolutely any wish, with no restrictions whatsoever. A wish on the Super Dragon Balls can even bring back things that Zen'o has erased. However, it is unknown what would happen if someone used the Super Dragon Balls to wish for Zen'o's destruction. It is known that Zen'o can kill someone who was given Complete Immortality by the Super Dragon Balls.
- The Pokémon anime, particularly its tie-in movies, uses several version mascot legendary pairs to embody this trope, usually in a manner that puts the setting of the movie where a given legendary pair shows up in severe peril, forcing Ash and another legendary Pokémon to break up the fight before they obliterate a city as collateral damage.
- Kyogre and Groudon from Pokémon Ruby and Sapphire (see Video Games below) dont get a movie depicting their rivalry; they instead get an arc of the anime's Hoenn season, which retells their battle in Sootopolis City after being awakened by Team Magma and Team Aqua, as in Pokémon Emerald. Just like in the games, Rayquaza promptly breaks up the fight once its attention is drawn to the problem.
- Dialga and Palkia, the embodiments of time and space from Pokémon Diamond and Pearl, usually do not fit this trope; most canons either depict them as being in a loose partnership or don't address the subject of how they interact with each other. However, in their movie, they get into a fight and cause a lot of collateral damage during their clash. Ultimately, Ash joins forces with Darkrai to force the two dragons to stop fighting and return to their own dimensions. However, in the next movie, Dialga gets lost in the Reverse World on its way home and is attacked by its resident Giratina, the embodiment of antimatter and the third member of Dialga and Palkia's trio. The side-effects of their fight end up complicating Ash's journey with Shaymin. The third and final movie of the set, Arceus and the Jewel of Life, has the three dragons set aside their differences and assist Ash in calming down their creator, Arceus, after it is driven into a berserk, catalysmic frenzy by a vicious betrayal.
- Reshiram and Zekrom get two variations of the same movie, reflecting the duality motif of their home games. Both movies involve one dragon teaming up with Ash and Victini to thwart the antagonist, who uses the other dragon; the difference between the movies lies in which dragon teams up with which characters.
- Depending on how you look at it, this trope is either averted or subverted for Xerneas and Yveltal, the embodiments of life and destruction, respectively, from Pokémon X and Y. True to their usual depiction as halves of a cycle rather than bitter rivals, the two legendary Pokémon dont interact much in Diancie and the Cocoon of Destruction. Yveltal spends most of the movie menacing Ash and Diancie during their journey, but it has no actual beef with the heroes and is just fulfilling its role as a destroyer. Xerneas doesn't appear until the final act, where it undoes the excessive damage Yveltal caused during its rampage.
- The X-Men foes Blob and Juggernaut are sometimes portrayed as this. (Juggernaut's superpowers boil down to being an Unstoppable Force, and The Blob's powers boil down to being an Immovable Object.) Though other comics have stated that The Juggernaut would simply win. (Blob is telekinetically bonded to the ground, but the Juggernaut could dislodge him, plus a substantial amount of the ground, as a single unit.)
- The other comics that depict Juggs the winner go with the fact that he's a mystically-empowered human, and not a mutant like the Blob. So it's more/less "mystic powers vs. mutant abilities".
- The Marvel Comic RPG says that Juggernaut could just force the ground The Blob is on to move and thus beating him. However, they do mention that this method would be moot if they were on a planet of Adamantium (though they didn't state what'd happen then).
- This is invoked by name in a Superman comic in which Superboy travels forward in time Superman is the irresistible force, Superboy the immovable object. The result is that Superboy gets sent back to his home time.
- Another example comes courtesy of Grant Morrison's All-Star Superman. His solution? "They surrender."
- The finale of Alan Moore's Swamp Thing story arc "American Gothic" ends like this. A group of male witches awaken "The Great Evil Beast," perhaps the ultimate Eldritch Abomination, as it is the complete and total absence of God's light, with the intention of destroying not only the universe but heaven itself. As it slowly moves forward, Etrigan, The Spectre, and Doctor Fate all try and fail to defeat it. Finally, the Hand of God Itself descends down. Everyone is preparing for the universe to end. . . but their hands clasp each other and "run together," showing that Good and Evil cannot exist without each other. If that sounds like a massive Mind Screw, it's because it is.
- Pony POV Series:
- The Alicorns and Draconequi are two sides of a coin, with the Alicorns representing Nature's Law, Order, and Creation while the Draconequi are Nature's Fury, Chaos, and Destruction. They once went to war with one another over the fate of Equus, as they had differing beliefs in what should be done. The Alicorns ultimately won, in part because Havoc's avatar went berserk and out of his control until it was defeated by Cadenza.
- Entropy is the Concept of the End and Oblivion while Fauna Luster is the concept of the Beginning and Life. While the two themselves never fought (as they generally are quite civil with each other), some of Entropy's power in the form of the Windigos was hit with some Fauna Luster's powers in the form of the Fires of Friendship. The Fires won, but they seem to be a larger percentage of Fauna Luster's power than the three drops of Entropy's blood composing the Windigo's.
- In Dark World Discord, the biggest representative of Chaotic Evil on the planet, and Grogar, the biggest representative of Lawful Evil went to war. The two were evenly matched enough for it to be a long war, but Discord eventually won. Given the nature of Dark World, it's likely Grogar won on at least a few occasions.
- When Megan used the Rainbow of Light against the Rainbow of Darkness, it turns out to be this as the two are 'twin' siblings born at the same time, one from the Alicorns and one from the Draconequi. As in the show, Light won.
- The Matrix: Neo vs. Agent Smith.
- In Little Shop of Horrors, Depraved Dentist Orin Scrivello (played by Steve Martin) meets his match in masochistic patient Arthur Denton (played by Bill Murray). After trying in vain to make Denton suffer, Scrivello kicks him out of the office in disgust after realizing that Denton is actually enjoying everything Scrivello is throwing at him. (Fun fact: This scene is based on a similar scene in the original 1960 film, in which the masochistic patient is played by a young Jack Nicholson.)
- A classic example comes from the Han Feizi. A merchant selling spears and shields claims that his spears can pierce anything and his shields can't be broken. When someone asks him what would happen if he were to strike the shield with the spear, he is unable to answer.
- Peter Crowther's "The Eternal Altercation" features a train in which the (identical looking) embodiments of Hope and Despair are locked in eternal combat. The train operator's job is to jerk the train if either of them gain too much ground.
- Forgotten Realms spin-a-yarn story "The Night Tymora Sneezed" had a codpiece that "awakens battle-lusts and... lusts in general" and a chastity that aids "[...] in resisting the distractions of the flesh and dedicating themselves wholly to the clear-headed vigilance the Supreme Guardian demands". Hilarity Ensues, of course.
- The Wheel of Time plays with this a lot. One of the key icons of the series is the yin-yang symbol, though with the dots removed. One of the central conflicts of the story is not only the eternal struggle between the Light and the Shadow, but the one between men and women, best encapsulated by the gender-striated magic system. The general conclusion is that harmony between the sexes produces the best results.
- The Tenets of Futilism features the mythology of the titular cult. Its members believe in a god of fortune named Crescis who is opposed to the god of misfortune, Decrescis. The cult's system is even a yin-yang symbol, only jagged and uneven at places.
- The world of Mistborn: The Original Trilogy was created by the gods of Preservation and Ruin working in concert during a one-off truce. Their vying over the fate of the world they made causes the conflict in the story, and ultimately the protagonist takes on the mantle of Preservation and uses it to annihilate Ruin, destroying both of them.
- The Chronicles of Amber: Has the Patern and Logrus, representing order and chaos respectively. The Unicorn and Serpent also.
- The Elenium and Tamuli have the primeval Top Gods Bhelliom and Klael, roughly corresponding to Order Versus Chaos, who clash whenever Bhelliom creates a world to decide who controls the world's development. Defied with the world on which the books are set, where they choose to be represented in combat by champions rather than risk the entire planet as collateral damage.
- Fate/strange fake: Gilgamesh's Enuma Elish is a blast with Anti-World properties, meaning at full power, it can cause an Earth-Shattering Kaboom. Enkidu's Enuma Elish is a blast that draws on the world's power to act as a linchpin for the world and heavens, and becomes more powerful against threats to the world. The two blasts cancel each other out.
- In The Flash (2014), Captain Cold's freeze ray is designed to project Absolute Zero and Heat Wave's flamethrower is designed to project Klein Temperature or "Absolute Hot". When Flash tricks the two into blasting him at the same time, the blasts cancel each other out and blows everybody back.
- In Classical Mythology, Amphitryon once sent Laelaps, a hound that can catch anything, after the Teumessian Fox, which can never be caught. Zeus's resolution to the paradox was to turn both animals to stone and cast them into the sky as the constellations Canis Major (the hound) and Canis Minor (the fox).
- Actually inverted according to original Taoism, where Yin and Yang are not opposites, but complements of each other. What is perceived as a "conflict" or "struggle" to keep the forces balanced is actually the two of them working in harmony. Furthermore, the clash of Yin and Yang, if it can be called that, is actually a good thing, as the ineffable Tao is formed and supported by the two absolutes working with each other.
- Dungeons & Dragons:
- The Blood War is a conflict between the devils and the demons to resolve which is the superior force in the multiverse, Chaos or Law. The demons, representing Chaotic Evil, have a theoretically infinite number of soldiers to call upon and some of those soldiers can be truly formidable individual combatants, but they rarely give consideration to advanced strategies and tactics, and they spend as much time fighting amongst themselves as they do trying to bring down the devils. The devils, representing Lawful Evil, have well-disciplined, well-trained soldiers and leaders who are ruthless tacticians to make up for the fact that they are frequently outnumbered. Both sides have fought each other to a stalemate for as long as the conflict has gone on.
- 3rd edition actually has a lesser known rule that solves this problem if you look at as the "spear/shield" version. In D&D specific trumps general, and thus the spear that can break any shield (specific power to break shields) trumps the shield that can't be broken (general power to be unbreakable).
- Since Exalted contains a lot of 'irresistible' and 'invincible' powers, they have a rule for this: a perfect defense always wins, even against a perfect attack.
- Several second-edition books written by freelancers with a poor understanding of the game's mechanics occasionally created "transperfect" attacks which trump this balance. This prompted the creators of the main game line — fearful of a Lensman Arms Race of transperfect attacks and transperfect defenses followed by trans-transperfects and so on — to state definitively that nothing can ever defeat a perfect defense, even if the thing itself says it can.
- Shield and Sword from Suikoden: Shield can withstand anything, and Sword can destroy anything. The inevitable Reality-Breaking Paradox that occurs when they clash can only be successfully resolved by Shield refusing to fight Sword, which results in Shield being wounded (making Shield thus unable to withstand everything) but not killed (making Sword thus unable to destroy everything). According to the lore in the games, all other runes were created when Shield and Sword initially clashed, which is why resolving the paradox creates the Rune of Beginning.
- One mini-boss in The Legend of Zelda: Oracle Games is defeated this way. You have to trick it into hitting its unbreakable shield with its unbreakable sword to destroy both.
- The Iron Clefts in Paper Mario: The Thousand-Year Door claim that their bodies can withstand any attack and their spikes can pierce anything. To defeat them, you have to knock them into each other with Yoshi's Gulp attack.
- In Pokémon Ruby and Sapphire, it's Groudon (representing the land) vs. Kyogre (the sea). Rayquaza the sky dragon needs to step in to break them up. (When pitting the two against one another in actual gameplay, Kyogre has a clear type advantage, but Groudon has an ability and movepool that's potentially well-equipped to deal with water-types.)
- Pokémon Black and White takes this a step further: the version mascots Reshiram and Zekrom are literal embodiments of yang and yin. They are this whenever they meet each other in battle, so much so that when one uses their signature attack, Fusion Flare/Bolt, the other will be forced to respond with a powered up Bolt/Flare. The faster one will have the weaker attack which is why N's legendary is two levels above yours. This also makes it so that the side that wins is dependent upon version (Yang wins in Black, Yin for White.)
- World of Warcraft Involves the following player spells, The Warlock's "Chaos Bolt" A spell that's stated to go through everything and anything and in fact, does. Then there is the Paladins "Divine Shield" which is simply put, "You cannot be damaged for the duration of this spell". The result: Chaos Bolt bounces off Divine shield due to the exact nature of the mechanics involved.
- The current version of chaos bolt had this ability removed to make up for the fact that it is now usable every 3 seconds or so.
- War Craft III had the opposite effects when a "Divine" armor type unit takes "Chaos" damage where the damage goes through the armor.
- Asura's Wrath has Asura, The Destructor vs. Chakravartin, The Creator.
- In Final Fantasy VII, the heroes have to stop the ultimate Black Magic, Meteor, by way of defeating the Big Bad, who's holding back the power of the ultimate White Magic, Holy.
- Fate/Grand Order: Sasaki Kojiro's sword style is described as an embodiment of "Infinity", as it gives the battle infinite outcomes to give him a 100% chance of victory. Miyamoto Musashi's sword style is described as an embodiment of "Zero", as it gives the battle one outcome to give her opponent a 0% chance of victory. When they fight, their clashing swords end up drawing them into a pocket dimension where it is said they would have fought each other for eternity. The stalemate was only broken because Musashi's Master Ritsuka Fujimaru was drawn into the dimension as well, which motivated Musashi enough to win.
- This trope and Order Versus Chaos are the driving forces behind the plot of "World of Light", the adventure/story mode of Super Smash Bros. Ultimate. See that game's page for details, as describing it here would require discussing the entirety of the story.
- The Han Feizi story is retold in Phoenix Wright: Ace Attorney. The "King of Prosecutors" trophy is a broken shield and knife, showing the result of the truth being pursued to its conclusion.
- In Fate/stay night, Lancer's ultimate attack uses his cursed spear Gáe Bolg to pierce his opponent's heart without fail before he even starts the attack. In the Unlimited Blade Works route, he throws the spear at Archer for even greater power. Archer responds with Rho Aias, a legendary shield that no spear was ever to pierce. Rho Aias successfully halts Gáe Bolg but is destroyed in the process, consuming a large chunk of Archer's power and shredding one of his arms. Lancer is completely dumbfounded.
- A similar showdown occurs in Fate/hollow ataraxia, where Lancer's Gáe Bolg is pitted against Fragarach. Gáe Bolg functions by reversing causality, with the cause being 'the opponent's heart is struck' and the effect is 'Lancer throws Gáe Bolg', while Fragarach reverses time and kills its opponent before their attack is made. The resulting pretzel of causality results in a double kill.
- Umineko: When They Cry has a Wizard Duel in which an 'Unstoppable Spear' and an 'Unbreakable Shield' are summoned. They both vanish right before they can contact each other.
- In Her Tears Were My Light, the very existence of Space, who creates, contradicts the existence of Nil, who erases. In the true ending, Time's goal is to resolve the conflict between them without letting one of them disappear.
- 8-Bit Theater gives us a scene in which Black Mage is hyped up on the absorbed power of the five greatest evils in the world: Kary, Lich, Kraken, Muffins, and himself. Fighter has already demonstrated the ability to block anything; Black Mage decides to put it to the test, and Fighter is not wrong. Let's let Black Mage explain it better:
Black Mage: I'm saying we're Fighter and Black Mage! Are we really going out on a superpowered duel? You [Fighter] can block anything and I'm basically a god. Our fight would raze the earth for miles and we'd solve nothing.
- Brawl in the Family shows us what happens when Kirby and Pac-Man both try to eat each other. They both disappear, by the way.
- Grrl Power: A minor supervillain claims to have both impenetrable skin and claws that can cut through anything in this strip. As Sydney points out, "Clearly one of those statements was false."
- Uncyclopedia: Both Mr. T and Chuck Norris are depicted as Memetic Badasses. According to one article (which has since been deleted or edited into oblivion), the fight between the two of them resulted in the Big Bang and the creation of the universe.
- Accordingly, some people joke that the biggest reason cloning should be outlawed is because cloning [insert name of your favorite Memetic Badass here] would make one of these possible.
- The winner of the October 2002 Animation round of The Internet Ray Tracing Competition (topic: Force) had some fun with the concept.
- Encyclopedia Dramatica: Longcat vs. Tacgnol.
- The SCP Foundation deconstructs it with SCP-225, a pair of objects, one unstoppable, the other immovable, both indestructible. The Foundation has no idea what would happen if they collided (though a multi-gigaton explosion has been speculated), and they really don't want to find out. Worse, they have no known way to prevent such a collision if it were going to occur, since neither object can be affected by anything.
Since all tests thus far have shown that neither SCP-225-1 nor SCP-225-2 can be damaged or moved by any means known, the possibility also exists that neither object would be annihilated, halted, or altered from their course even by contact with the other. If this is true, then a collision between SCP-225-1 and SCP-225-2 has the potential to [DATA EXPUNGED].In this circumstance planetary evacuation may not be sufficient
- In Fine Structure, Anne Poole is immortal and indestructible. Dropping her into a black hole makes physics break down and the Imprisoning God go into failure mode.
- In an episode of Star Wars: The Clone Wars, the Son and the Daughter, embodiments of the Dark and Light sides of the Force, clashed when the Son attempted to turn Anakin to his side and the Daughter tried to stop him. Their battle was cut short when the Father, embodiment of the Balance of the Force, intervened.
- In an episode of The Fairly OddParents!, Timmy wishes for both of his parents to be the best surfer ever, forgetting that two people can't be simultaneously better than each other at something. The resulting paradox traps them in a limbo where they are continually trying to beat each other, until Timmy breaks the limbo by putting himself in danger so that they have to save him.
- The Legend of Korra brings us Raava and Vaatu, two powerful spirits on the opposite sides of the same coin. Raava (colored blue/white) is the female spirit of order and peace, while Vaatu (red/black) is the male spirit of darkness and chaos. They battle every 10,000 years for the fate of the world, equal in power unless the balance is disturbed. In addition, neither one can ever truly destroy the other, for even if one spirit is destroyed, it will be fully restored by the next 10,000 year cycle.