Either/Or Prophecy

A fantasy world where all prophecies are mandated by the Universal Laws to be 100% accurate easily lends itself to reveal-the-plot prophecies, particularly when the author isn't skilled in the fine art of obfuscation and Prophecy Twist. However, laying out the plot beforehand is a good way to kill any plot tension. All but the most incompetent of authors realize that something has to be done.

As its name implies, an Either or Prophecy specifies two possibilities. Either the good will triumph over evil or the Big Bad will mop the floor with the pesky heroes and reign unconquered forevermore. The point is that there is no middle ground.

It is implied that each of the possibilities has a 50% chance of coming true, but in practice, the good will always triumph and the evil option is just there to motivate the characters (and distract the audience). Occasionally, through a Prophecy Twist, both halves come true. And it's always possible that the heroes might say "Screw Destiny" and Take a Third Option.

A little thought reveals that the inverse of this trope, when applicable, falls under No Man of Woman Born. The latter trope requires that two or more conditions be met that are supposed to be contradictory (and thus interpretable as Neither-Nor), but in reality aren't, leading to the inevitable Prophecy Twist.

Anime and Manga

 * Naruto has the head frog sage of Myobokuzan foretell

Comic Books

 * In the Tom Strong story with the interdimensional Aztech Empire, the computer-god Quetzocoatl-9 tells the High Priest that if he invades the world with superhero Tom Strong on it "there will be a great victory". The victory in question was Tom Strong destroying the hardwired controls that left Quetzocoatl-9 enslaved by his priesthood. Thus the computer-god destroyed the priest and took direct control of his empire.
 * A Spider Man annual, "Night of the Bend-Sinister", begins with a prophecy from the Book of the Vishanti, stating that once every 60,000 years a mystical conjunction called the Bend-Sinister is possible, and at that time demons will succeed in invading the Earth unless "a mighty sorcerer'' joins forces with "one who both spider and man". Fortunately, Spider-Man and Doctor Strange are old friends...

Fairy Tales

 * Parodied in a fairy tale in which a woman asks a wizard about the sex of her unborn child. She is told: "The child will be either a boy or a girl."
 * But in fiction it's sort of good news already.
 * One Norweigan folktale has a village idiot make his way to fame and fortune via well-timed ambiguous statements. The last test set before him by the king is to predict the sex of the queen's unborn child; he has her walk towards and away from him before declaring, "When she walks towards me it looks like a boy, but when she walks away it looks like a girl." She gives birth to twins.

Film
"When single shines the triple sun
 * In the film The Dark Crystal:

What once was sundered and undone

Shall be made whole; the two made one

By Gelfling hand, or else by none."


 * The Skeksis massacred the Gelflings to prevent the healing of the Crystal, following the logic that so long as no Gelfling was alive at the conjunction nobody could repair it. Sadly, they missed two.
 * Star Wars - It was prophesized that the chosen one would bring balance to the force. Well, the chosen one did, first in Episode 3 Revenge of the Sith by, and then in Episode 6 Return of the Jedi by.

Literature
""Neither can live while the other survives.""
 * In Chronicles of Thomas Covenant, Thomas Covenant is prophesied to "save or damn" the world.
 * David Eddings loves this. The Belgariad has two competing prophecies which, combined, amount to one big Either or Prophecy. In the sequel series, the same continues in a slightly tweaked form, so that the winning future is determined by one person who is supposed to be totally impartial.
 * The prophecy at the heart of the Harry Potter novels does not describe the eventual triumph of good over evil, but instead simply declares that Harry and Voldemort are destined to battle each other to the death. The aftermath of that battle is not something the prophecy is concerned with.
 * When the prophecy was made it specified a child who could be either Harry Potter or Neville Longbottom, and only Voldemort's actions settled it on Harry.


 * Almost all important prophecies in Terry Goodkind's Sword of Truth series of novels are of this type. The fourth book puts a twist on this, as both possible fates seem to require the hero's death...
 * The very same prophecy also mentions his beloved will betray him. It's never explained completely, but I assume it meant that they both thought she was betraying him, while later they both realised she had not been betraying him. Or something.
 * His beloved has to betray him (and it is foretold that she will do so ) in order for him to  . And she does. Once she realizes, she begs the only witness not to tell Richard. The witness's response:
 * It's also worth noting that
 * In The Last Rune series people are trying to save or kill Travis since he's fated to both save and destroy the world (usually based on how optimistic they are). Turns out he destroyes the world then rebuilds it exactly the same only without the Big Bad.
 * Depending on what happens to the Lightstone in the Ea Cycle, either an Age of Darkness would start and a Cosmic Horror would destroy most of the universe or The Chosen One would bring about an Age of Light and lift everyone to a higher state of existence.
 * The Wheel of Time has one of these among a hundred. Gawain will either kneel to his unofficial girlfriend Egwene, or kill her.
 * The various viewings of the future, most notably Min's, qualify as well. They're accurate readings of The Pattern that shapes the past and future. However if the Big Bad wins The Pattern itself will be destroyed, rendering the viewings false.
 * Also used in one of the prophecies regarding Mat Cauthon, who was told "You will go to Rhuidean." He asked the prophet "Why do I have to go," and was told "If you do not, you will die." Mat could theoretically tell his destiny to screw off, if he was willing to die for it and possibly doom the world.
 * Also, another one of Min's viewings of Siuan Sanche and Gareth Bryne said that "You must stay close to each other or you will both die."
 * This is seen somewhat in Dune, where Paul and later Leto II can see possible futures and must choose the best one to carry out.
 * In Percy Jackson and The Olympians, there is a prophecy that a half-blood child of one of the big three will either save the Olympian gods or damn them...
 * In Warrior Cats, a prophecy says, "Fire alone can save our clan". It doesn't specify if it will or not.

Live Action TV
"On the seventh dawn of the seventh day;
 * The key prophecy in First Wave from the Lost Quatrains of Nostradamus:

A twice-blessed man will roam the fields.

Doomed to shadows with his brethren;

Or savior to all who walk the ground."


 * Basically, it's up to Cade (the "twice-blessed man") whether Earth will be conquered by aliens or not.
 * The Shanshu prophecy in Angel says that the vampire with a soul will either save the world or destroy it during the Apocalypse.
 * Lexx- a Brunene-G will destroy his divine shadow. so of course his divine shadow kills all of the Brunen-G...

Newspaper Comics

 * Candorville parodies this during The Reveal.

Tabletop RPG

 * SJ Games' In Nomine RPG features the Archangel of Destiny, who knows with divine certainty that ultimately everything will Turn Out All Right... and the Prince of Fate, who has an equal certainty that Hell and the forces of evil will triumph. Fate and Destiny hang in a sort of metaphysical eigenstate over any sort of prophecy in this setting, and as angels and demons, the player characters themselves are often the 'spooky action at a distance' that resolves them.
 * The Usurpation of the Solar Deliberative in Exalted was triggered when the Sidereals read the Loom of Fate and noticed a gigantic celestial clusterfuck would ensue if the Solars kept doing things as they were. They could either tell the Solars about this and hope that they'd yield to the advice, or overthrow the Solars and ensure that the crisis did not come to pass. They chose the latter, which had its own string of nasty side effects. The best part? Due to the manifestation of the Great Curse upon the Sidereals, the choice to kill them all did not avert the dark and miserable future that would come if they failed to persuade the Solars -- it only delayed it, and if not for the careless arrogance of the forces of Evil, there wouldn't have been any Solars to stand in the way.
 * The Draconic Prophecy in the Dungeons and Dragons setting Eberron can be said to follow this trope; it describes the inevitable results of certain events, while remaining silent as to whether these events will ever happen. This works out perfectly for adventures: If event X happens, event Y will happen. If you want to prevent or cause event Y, you've got to worry about event X.

Theater

 * In The Women of Trachis Deianira reveals the prophecy that after finishing his current task Herakles would either die or live a happy life. She is appropriately concerned about this.

Web Comics

 * "Do I get to cause the death of any of the following: Miko, Miko's stupid horse, Roy, Vaarsuvius or you?" "Yes" "Sweet! Which one?" "Next!"

Western Animation

 * In Disney's Hercules, the Fates prophesize that Hades will overthrow Zeus at a time when the planets align perfectly unless Hercules fights to stop him. Hades spends most of the rest of the movie doing his darnedest to kill Hercules before the deadline.

Video Games

 * The game Super Paper Mario revolves around a prophecy of multiversal destruction written in a book called the Dark Prognosticus, rivaled by a prophecy that the multiverse will be saved by a band of heroes written the book's Good Counterpart, the Light Prognosticus.
 * This one gets a bit confusing: both books predict almost exactly the same set of events coming to pass; the Dark Prognosticus mentions a band of heroes fighting for the multiverse's survival as well. Eventually it is revealed that
 * One of the plot points in Metal Gear Solid: Portable Ops revolves around a pair (well...) of twin psychics, one of whom sees the main character destroying Metal Gear, the other of whom sees the main character starting a terrible war. Of course, the Prophecy Twist is that the girls later realise that they were both right. (Since the game is a prequel this surprises no-one - we've already seen the main character try to start a war, twice, in the latter timeline.)
 * Baldurs Gate II: Throne of Bhaal reveals that the prophecy about the Bhaalspawn bringing great destruction was actually an either-or condition: Either the Player Character will succeed, or the destruction will take place. (That is to say, even more destruction. Apparently the prophet specified some high level of destruction that would be even worse than what did happen in the games and potentially could happen because of what the Player Character could do after them.)
 * Legacy of Kain, Raziel sees murals depicting two champions that will battle each other to decide the fate of Nosgoth, but the victory is undetermined as the murals show both champions slaying the other. Then in a serious Prophecy Twist, we find out
 * In Brutal Legend, the prophecy foretelling Eddie's arrival from the Modern World to the Age of Metal says that he will either destroy the world or deliver the humanity from the demons' evil.

Real Life

 * Historical example: King Croesus of Lydia asked the Oracle of Delphi what the result would be if he took his troops across the Halys River and attacked the Persians. Her answer was, "If you do, a great empire will be destroyed." The seer didn't specify which great empire. In the end, it was Croesus' kingdom, not Persia, that was destroyed, but the seer would have been "right" either way--but note that there was no way the seer could have known that Lydia or Persia would be utterly crushed (rather than a stalemate or minor gains for one side or another). That makes this a classic example of the trope, eliminating all possible middle ground.
 * Prince Siddharta Gautama was foretold at birth to be either a great king or a great sage. His father, preferring the former, tried to shelter him from the world's pain and sorrow. When he did catch a glimpse, he ran away to meditate and became Buddha.
 * Derren Brown claimed in an interview to have heard a psychic tell the person they were "reading," "You either live alone, or with other people."
 * A basic trick for mentalists and phony psychics is to throw these out so fast you only notice the correct sides.
 * Just having pets is neither.