Scry vs. Scry

"Pop Girl: I've seen you die, little girl.

Cassie: Then you know it's not here and it's not today."

- Push

There are a lot of characters who can foresee The Future, and sometimes the future is obliging enough to be malleable to change. So, what happens when two characters capable of seeing the future and changing it have different ideas about where it ought to go? You get a case of Scry Vs. Scry.

These psychics pit not just their oracular ability against each other to see who can predict most accurately and farther in time, but also their ability to plan and manipulate as well: guiding allies, manipulating and outwitting enemies, and trying to "out foretell" each other's changes in a case of Xanatos Speed Chess where the prize is control of Fate itself. This can potentially be the ultimate Gambit Roulette, not the least because both sides are continually re-spinning the wheel on an unfavorable result.

There are a pair of related scenarios that parallel this. One is when two time travelers attempt to beat each other by progressively changing time and reverting the other's changes, their goal being to change time such that the other ceases to exist or is unable to Time Travel. The other is when two crazy-good martial artists prepare for a duel: they lock eyes, work out all the moves they will go through, determine that it will be a draw or mutual kill, and ultimately decide not to fight at all.

The name of this trope is a pun on Mad Magazine's Spy vs. Spy.

Contrast Prescience Is Predictable.

Anime and Manga

 * Much of CLAMP's X 1999 is conflict led by Yumemi or dreamseers on opposite sides.
 * Oh god, speaking of CLAMP- Tsubasa... just, Tsubasa. Yuuko, Ass-chin Fei Wong Reed. And on top of that, Clow Reed, who'd been dead for hundreds of years prior, could see the future better than the aforementioned two and set it all up before he died.
 * The basis of Mirai Nikki, where the titular diaries allow knowledge of the future, and all diary holders are forced to fight to the death.
 * The manga Un Cassandra consists of the protagonists trying to Screw Destiny when they learn of upcoming disasters (including one protagonist's death) while another tries to assert You Can't Fight Fate by subverting their attempts at every turn.
 * Suzumiya Haruhi has two rival factions of time travelers, with Mikuru and "Sneering Bastard" as representatives. The latter frequently expresses annoyance at the Stable Time Loops he has to follow, but he's here for something.
 * Vision of Escaflowne is concerned with a battle of Scry vs. Scry between Big Bad Emperor Dornkirk, who foretells and manipulates fate through technological means, and protagonist Hitomi, who does so through "natural" means.
 * Gundam Wing features a Scry vs. Scry battle between Quatre and Dorothy, albeit with both using the ZERO system, which directly interfaces with the user's brain with advance calculations predicting the most probable movements for victory or defeat. However, if the user's brain is unable to process the sheer quantity of raw data being interfaced, the user vividly hallucinates from all the possibilities and becomes overloaded too many statistics and estimated values. The result is temporary insanity.
 * Aiki has a case of the martial artist version, in which Joukyuu, who is supposed to be a master of analysis, surrenders a fight against a similar stylist because he knows that he would lose.

Comic Books

 * The Clock King and Rose Wilson both have the power to see about 4 seconds into the future. Their fights tend to be evenly matched.
 * Batman and Captain America's battle during JLA-Avengers: they exchanged a few blows to test each other, then decided that neither would win, at least for a very long time, and chose to talk things out instead.

Film

 * The two Watchers in Push, as per the quote at the top of the page. While they both have the power to see the future, it's implied to manifest in different ways: Cassie's visions come in the form of snatches of imagery, while the Asian girl is said to be able to divine intentions, not just sights. This leads to a complicated Gambit Roulette where the protagonist hands out sealed instructions to his allies, reasoning that the Asian girl won't be able to predict their actions if they have no idea what it is they're going to do until they do it - and then he has his own memories of creating the envelopes erased to seal the deal.
 * It is more implied that all Watchers work this way. Cassie just isn't as good at is as Lollipop Girl since she is so much younger and less experienced. Despite most likely having much more potential, she just hasn't had a lifetime of practice yet.
 * The Jedi vs. the Sith in Star Wars.
 * To add to that, masters of combat have the ability to see a second or so into the future using the force. This is how they manage to effortlessly block blaster shots and quick slashes. A combat between two masters is thus an example of this trope.
 * Subverted by Fighter in The Wind, a Japanese movie about a real life Korean man who became a Karate master. Before having a duel with his rival they have a vision of the katana wielding rival being stopped before he can unsheath his sword and then losing. When they do fight, however, the rival is able to draw his katana and lay it flat on his opponent's head, showing that he could have easily won. Then they fight for real.
 * There are some suggestions that the movie Next may be one of these, given that and
 * The final confrontation between Holmes and Moriarty in A Game of Shadows becomes this since both are capable of fully predicting fights. The first vision is narrated by Holmes and shows how he'd win. Moriarty then interrupts and narrates counters that he will be using. Holmes comes to realize through their mental debate that Moriarty will win because Holmes is injured but Moriarty is well-rested. When the fight takes place for real, Holmes
 * At the climax of Bill and Teds Bogus Journey Bill & Ted are facing de Nomolos in a Battle of the Bands. Each has a time machine, and each keeps changing the present by going back into the past in the future to fix things. Bill & Ted have the epiphany that only the one who wins will be able to go back to change things, including changing things their rival is going to change in order to lull him into a False Sense of Security.

Literature

 * David Eddings' Belgariad and the follow-up series The Malloreon involves a conflict between two prophecies, which are personified and able to communicate with the protagonist and the villain respectively.
 * Eddings appears to be rather fond of this trope. Another David Eddings book, The Redemption of Althalus, actively pitted two groups with the ability to change the past and future against each other, with the major edge of the protagonists being a creative boy who tends to have completely unorthodox applications of the capability.
 * Two characters in the Twilight saga actually play chess like this. Alice sees what Edward will do; Edward reads Alice's mind to find out what he will do. This ends with Alice knocking over her own king without Bella/the audience seeing any pieces moving.
 * To clarify; Alice can see the future and Edward can read minds.
 * Discussed in The Cursed by Dave Duncan, in which those who see the future essentially go insane if they change said future. One oracle who's a supporting character had a friend who went insane this way, and the heroine is told that to truly understand him she should ask him whether he saw the future where the friend did nothing or the future where the friend went insane. (Incidentally, she never asks, allowing the author to avoid that bit of Fridge Logic.)
 * A few times in Dune, such as Emperor Paul vs. Guild Steersman Edric in Messiah and Paul vs. his son Leto II in Children.
 * Leto II eventually decides that the existence of competing prescients is nothing but a burden on humanity, and so enacts a millenial plan to breed humans who are invisible to prescience, as well as facilitating the creation of a device which conceals anything or anyone contained within, all for the sake of putting a bit of chaos back into human development.
 * His conversation with Siona in the desert could indicate that he did this, along with encouraging the diaspora of humanity after his death, to ensure that no matter what horrible catastrophe happened, not even a prescient person could find and eradicate all of humanity. The memory he showed her may have been from the Butlerian Jihad against the killer robots.
 * Actually, if one pays attention to various pieces of dialogue spoken by Leto II throughout the book, one discovers that Siona is actually seeing the horrifying future that Leto has been trying to prevent during his reign. It is mentioned early in the book that the Ixians had been working on developing an intelligent hunter-seeker. Well, if they're going to do that, why not apply it to other machines as well? Apparently, somewhere along the line the shit hit the fan, and It Got Worse. Much much worse..
 * In His Dark Materials, all the factions have people who can read alethiometers, though Lyra has the ability to read it with greater speed and accuracy than the others, and she's working on neither side.
 * In Mistborn, Allomancers can see a few seconds into the future--not enough to generally be useful, but enough to give them a massive tactical advantage in battle--by using the fictional metal atium. When two atium-using Allomancers get in a fight, the result is a very... compressed version of this trope.
 * In Good Omens Crowley (a demon) points out that while, yes, prophesies say that God will win in their final conflict, there are also those that say the devil wins. Naturally, all of the prophets that say the former are already on God's side and all that say the latter are on Lucifer's side, suggesting that both should be taken with a grain of salt.
 * Aziriphale (an angel) claims that all these predictions are just propaganda, and if there were no uncertainty, there wouldn't be any point to the war between Heaven and Hell in the first place.
 * He also points out that all prophets, except for Agnes Nutter, had some sort of "static" preventing them from predicting the future with total accuracy.
 * By the end Crowley adjusts his view.
 * But that's because God isn't really on Heaven's side, but his own, and perhaps of humanity, that both Heaven and Hell consider mere pawns.
 * In Stephen Baxter's Xeelee Sequence book Exultant, Humanity fights a War against the Xeelee over the Milky Way Galaxy where both sides can send information backwards in time using FTL. In practice, neither side can ever get an advantage. This goes on for tens of thousands of years.
 * And then in one of his later Xeelee novels (The Ring I believe) you find out that the Xeelee were really mainly fighting another entity entirely. One with the intent of essentially destroying every star in existence so as to let themselves live longer and easier. Humanity was only ever a distraction that the Xeelee put up with until we got too annoying then they put us in our place. Oh and those pesky  As this was the first novel in the sequence I read it was a rather disturbing first impression of the Xeelee.
 * The martial-arts version is discussed in Market Forces by Richard K. Morgan, with one character speculating that the system would be prejudiced against those with itchy eyelids.
 * Pretty much the entire plot of Robin Hobb's Farseer/Liveship Traders series eventually turns out to be a case of this.
 * The short story "How Much Shall We Bet?" from Calvino's Cosmicomics is about two cosmic beings taking bets on what will happen over the course of human history. It starts out with predicting the most significant historical events (e.g. the first civilizations, great historical leaders), but after all the major events have already been bet on, the predictions get more and more trivial (e.g. Which way will that particular person turn on a particular day? What will be that newspaper's headline on a specific day?) with the narrator losing an increasing number of bets as his seemingly foolproof system begins failing along the way.
 * In The Cycle of Fire, during Jaric and the Morrigierj's climatic duel, both can see all the likely futures for months ahead, possibly centuries, but the Morrigierj prevents Jaric from seeing the positive outcomes.
 * In Greg Keyes' "Kingdoms of Thorn and Bone", between
 * In A Connecticut Yankee in King Arthur's Court by Mark Twain, the Boss engages in this trope with various cranks and quacks (including Merlin). He is, strictly speaking, also a fraud - though having been thrown back in time 13 centuries does tend to give him a bit of an advantage.
 * This appears to be the case between Geser and Zabulon in Night Watch, two ancient Others with a magic rating of Beyond Categorization (i.e. any open contest between them would result in massive death and destruction). Both can visualize fate lines and predict outcomes decades in advance. Some characters attempt to do the unexpected, only to realize this was all part of the plan.
 * Sword of Truth has Zedd describing the use of magic in battles like this. Wizard forces are on the back lines simultaneously attacking and dispelling each other across the battlefield, so the end result is a bunch of guys waving their hands with nothing going on a majority of the time. When fireballs aren't destroying your army is a good sign your wizards are doing their job.

Live Action TV

 * Doctor Who, "The Fires of Pompeii": two soothsayers (one male, one female) compete to see which of them can tell more about the Doctor and Donna.
 * Does the Doctor's earlier seemingly senseless word game with the male soothsayer count?
 * The Doctor Who parody show Curse of the Fatal Death had the Doctor and the Master in a standoff of sorts where they compete to change the past so that the present would work to their current advantage. Obviously the person who was able to go back the furthest into the past and anticipate the changes that the other would make would come out on top of the situation. (The standoff ended with the Master accidentally falling into a sewer that took him 300 years to climb out of. He somehow managed to do this three times.)
 * Leverage has the martial artist variant, though eventually they do start fighting for real. Who the eventual winner would have been isn't clear, as they didn't finish the fight.

Tabletop RPG

 * In Warhammer 40000, Eldar Farseers, Chaos worshipers of Tzeentch, and some human psykers are all capable of foresight. With the setting what it is, any competition between them results in catastrophic body counts.
 * Then throw in the Cabal from Legion and watch as everything goes straight to hell on the Gambit Pileup Express.
 * Whats makes the whole thing even more confusing is that Tzeentch is such a obsessive chessmaster that sometimes the person he's going up against is himself. As the god of change the only thing that matters is playing the game, since winning would lead to a form of stagnation.
 * Time Combat in Continuum works like this. Rival spanners try to undo each other's changes in the timestream and, in so doing, frag their opponent into quasi-sentient time goo.
 * Rather common in both Mage: The Ascension and Mage: The Awakening, and actually within the reach of a starting player character. As a result, you get a non-negligible number of Mages who walk around warded in things which prevent others from scrying them, while they're looking ahead in the future constantly.
 * GURPS Supers has an example in its "Mixed Doubles" supplement: Hunchback was a British precog whose powers allowed the Allies to counter the advantage of the Nazi's own precog during world war two.
 * The martial arts version crops up in Legend of the Five Rings during iaijutsu duels. Each swordsman gets a limited ability to "see" some or all of his opponents stats, and some battles end before the first stroke if one combatant decides he's completely outmatched. It is not considered dishonorable to forfeit a duel this way.

Video Games

 * In Super Paper Mario, two books of prophecy exist; the Dark Prognosticus, which foretells the doom of The Multiverse, and the Light Prognosticus, which fortells a group of heroes foiling the predictions of the Dark Prognosticus. Guess who the hero is?
 * Actually, the Light Prognosticus isn't a telling of a future but a means and thoughts on how to combat the prophicies held in the Dark Prognosticus.
 * The plot of Time Hollow revolves around main character Ethan Kairos manipulating time to stop an antagonist using the same abilities as himself.
 * Achron brings us the time-travel version of this. In multiplayer. The players are entities that can shift their perception up and down the timeline freely, while still remembering versions of events that became undone.
 * Legacy of Kain has this in spades. Especially interesting considering the series' (awesome) unholy marriage of You Can't Fight Fate and Screw Destiny: Anti-Hero Kain knows that he has a world-shattering Sadistic Choice coming, and so goes back through slightly altered versions of the same events over and over again, hoping that, eventually, the right Butterfly of Doom will come along and allow him to Take a Third Option. Naturally, it gets more complicated from there.
 * In Sam and Max,
 * In Radiant Historia, two Chronicles, Black and White, allow their holders to hop backwards and forwards in time, as well as to jump between alternate timelines. Stocke tries to save the world by using the White Chronicle to guide it through its "True History", while the wielder of the Black Chronicle tries to do the exact opposite.

Web Comics

 * Celesto Morgan versus Dominic Deegan... sort of. Their conflict escalates beyond this fairly quickly, but when they first butt heads, it's as competing oracles.
 * Also Dominic vs. Vilrath in the Visions of Doom arc.
 * In Casey and Andy strip 209 two highly intelligent good and evil counterparts try to outwit each other while predicting their opponent's countermeasures.

Web Original

 * The Chessmaster and Mrs. Potter in the Whateley Universe. The methods by which they use their precognitive abilities are very different - during the Halloween Invasion, the Chessmaster shows himself to be a consummate micro-manager, sending instructions to his minions every few minutes in response to every little change in the situation on the ground. Mrs Potter, on the other hand, does nothing but make a single phone call Well, Mrs. Potter also made absolutely sure all her pieces were in the right place to do things. Still, Guess who wins?