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Fan Fic / Chaos Theory

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But mostly? The assorted plans at play here would be going very, very wrong due to the actions of a no-name, no-count, utterly talentless Magus by the name of Shirou Emiya. He had no magic worth mentioning, no combat experience of note, and no plan for or knowledge of the War he was about to enter. He did, however, have one trait that had derailed a countless number of such grand, far-reaching schemes throughout history.

You see, he really, really wanted to be a hero.
— Prologue

Chaos Theory is a Fan Fic in the Fate/stay night branch of the Nasuverse. As of May 21, 2018, it is now complete with 44 chapters. Posted on Fanfiction.Net by the Moczo siblings, who wrote Manchester Lost, Uninvited Guests and Infinity, among other assorted fics. The plot of this fic deals with the ripple effect of how one seemingly insignificant choice can completely and unrecognizably rewrite fate.

In this story, the proverbial "nail" in question comes when Shirou Emiya first meets Illyasviel von Einzbern, who in canon delivers her warning to him about summoning a Servant before departing. Here, however:

Shirou stopped, and watched the girl stroll past. She… something about her just said 'do not follow me' to his mind. Like he was risking his life by approaching her. But…

Sometimes, it's the tiniest little things that can change the world.

Shirou sprinted after the departing girl, shouting, "Wait, wait up a second!"

The girl, her eyes wide with more shock than should probably have been in them, turned to face him. "Um... huh?" She said, eloquently.

Shirou knelt down so that he could look her in the eyes, and put on his warmest smile. Her clothes looked very well made, so best to assume she had money and behave with proper respect; though really, he would have anyway. Even if she wasn't actually upper-class, it was the rare little girl who wouldn't get a small thrill out of being talked to like she was a Lady. "Hello, ojou-chan. Are you all alone?"

Having believed Shirou to be—like Kiritsugu Emiya—a heartless person, this act of kindness throws Illya off her game. In addition to that, the effects of this meeting, though small at first, steadily propel the Holy Grail War into a never-before-seen direction, where friends might become foes, the people you trust are keeping secrets from you, and villains with far-reaching schemes find their plans derailed—and in some cases, enhanced—by simple chance.

In the middle of all this chaos are two souls fighting for survival. Caught in a conflict he never saw coming (and this time without Rin Tohsaka as his guide and ally), Shirou must, along with Saber, find some purchase in a conflict that could destroy everything he cares about. Meanwhile, Illya, who grows closer to Shirou than she ever thought possible, must face her past and her inner demons as she fights a war that will not only test her most fundamental beliefs, but just might prove to be her much-needed salvation.


This story, considered by some fans to be a Fanon interpretation of the never-made "Illya Route", takes many elements from the Heaven's Feel route while nonetheless telling its own unique tale. Started in 2010, it combines the Moczo-brand style of humour (Uninvited Guests & Manchester Lost) with their other strengths of superb plotting, characterisation, and story-telling (Infinity) to create a worthwhile reading experience.

This story comes with very positive recommendations on TV Tropes.

Chaos Theory contains examples of:

  • 11th-Hour Superpower: The heroes fighting inside the mountain each receive a power-up as they're about to die, visually manifested in some sort of golden power implied to be granted by Merlin, and/or by access to Avalon even for the ones who aren't Saber and Shirou.
  • A God Am I: Dark Sakura claims she will be a goddess when Angra Mainyu is born into the world.
  • Affably Evil:
    • Caster Alter is sympathetic and quite friendly toward Sakura.
    • Lancer is his usual amiable self even after he gets altered by the Shadow, despite being much more aggressive.
    • Avenger is surprisingly polite once incarnated. Everyone is weirded out by how far off it is from their expectations of a mindless monster. Presumably Kirei's contribution to it taking form was a factor there.
  • An Arm and a Leg:
    • Gilgamesh loses his left hand in the battle against Saber, Berserker, and Archer.
    • Lancer Alter cuts off Saber's legs to stop her from being consumed by the Shadow.
    • Archer loses his right arm in the final battle against Gilgamesh. Gilgamesh loses his remaining hand at almost the same time.
  • And I Must Scream: Caster is turned into a dragon, all that remains of her being part of her torso and her head, silently screaming when the dragon roars.
  • Anti-Hero: Illya shifts into this at the start of the story—much to her consternation, because Being Good Sucks (see below) due to coming with further moral boundaries that she's forced to adhere to for Shirou's sake. The later perks, however, make her less disgruntled about it.
  • Anti-Nihilist: Illya moves into this as time goes on, acknowledging that Humans Are Flawed, and that the world may be screwed up, but that people don't have to be defined by the negative.
  • Apocalypse How: The heroes' final enemy wants to enact a Planetary Species Extinction event (against humans). Although it fails, the battle to stop it is a Planetary Societal Disruption event, as the existence of the supernatural is exposed to all of Japan, and the news is expected to spread through the Internet to the rest of the world.
  • Arrow Catch: Dark Sakura captures Shirou's Gae Bolg, and tells him that even if it had hit, it wouldn't have worked.
  • Arson, Murder, and Jaywalking: Upon learning that Shirou left the house while sick and hasn't been back for several hours, Fujimura is worried that he "could be passed out in a ditch and die of illness! He could be murdered! He could get me fired."
  • Asshole Victim: It's implied and later explicitly stated that Rin kills Shinji, but the perpetrator and the victim's victim agree that he deserved it.
  • Assimilation Plot: Dark Sakura plans to absorb everyone into Angra Mainyu and send it to the Root.
  • Badass Creed: As usual, Shirou's Unlimited Blade Works chant.
    Shirou Emiya: I am the bone of my sword.
    Steel is my body, and fire is my blood.
    I have created over a thousand blades.
    Blind to the future.
    Fleeing the past.
    Withstood pain to create many weapons, each one a guiding light.
    The paths are infinite, but I can only walk the one I've chosen.
    The road ascending, carved by Unlimited Blade Works.
  • Bait-and-Switch:
    • A corrupted bounded field has just been suddenly erected by a villain at the end of a chapter. The next chapter opens with, "It was a catastrophe of epic proportions. The single worst disaster that had ever befallen this world. A thing of corruption and destruction that despoiled all it touched." This is then shown to be Sella's reaction to Illya having left the Einzbern base on her own, all day, multiple times.
    • Illya opens the front door, expecting her maid and no trouble. However, what the reader knows and she doesn't is that two villains have set out to abduct Illya. Then:
      "… No fun at all," Illya muttered, opening the door. "Sella, you took longer to get here than I-"

      And then the attack began, the most dangerous person in Fuyuki striking with sudden, brutal efficiency that broke Shirou's defenses instantly.
    ...but it's just Taiga, along with the expected maid.
  • Bait-and-Switch Gunshot: Type 2. Lancer Alter aims at Rider and uses his noble phantasm, but at the last second sends it at Assassin.
  • Beam-O-War: Saber's and Mordred's noble phantasms meet this way and explode.
  • Because You Were Nice to Me: This is the fic's turning point from canon: the whole reason Illya grows fond of Shirou.
    Illyasviel von Einzbern: Because he was nice to me. He was sweet and kind and treated me like I was special when he didn't have any reason to, and he never asked for anything in return. You'd be surprised how rare that is.
  • Being Good Sucks: Illya becomes frustrated with how much harder it is to do right rather than easy, to the point of a near-tantrum over it. It pays off some in Chapter 15, but even afterwards she's still quite frustrated.
  • Berserk Button:
    • Three of Gilgamesh's are pressed at once: The Shadow is running around threatening his kingdom, Archer is running around copying his treasures, and his Saber has been tainted by the Shadow. This prompts him to enter the fray when all of the above are fighting at Ryudou Temple.
    • Avenger summoning Enkidu deeply pisses off Gil.
  • The Berserker: Berserker, obviously, and Saber Alter at first.
  • Be Yourself: Shirou attempts to use Unlimited Blade Works by copying Archer's chant, but it doesn't work. Archer appears to him in a vision and tells him he can't always succeed by copying people. Shirou then makes up a new chant that draws on his experiences instead of Archer's and it works.
  • Big Bad Ensemble: It's a combination of Kirei Kotomine, Gilgamesh, Zouken Matou, and Caster Alter.
  • The Big Bad Shuffle: It starts out with the above Big Bad Ensemble Zouken and Caster Alter being the main antagonists, working together to fulfill their agendas while simultaneously plotting against the other, while Kirei merely observes and Gilgamesh does whatever he wants. However, after Chapter 31, Dark Sakura kills both Zouken and Caster Alter, Kirei becomes The Dragon, and Gilgamesh is reverted to a child after a near-disastrous encounter with Dark Sakura and ends up doing a Heel–Face Turn. Near the end, though, Sakura is separated from the Grail's influence, but Kotomine sacrifices himself to incarnate Angra Mainyu as Avenger, whom proceeds to take over as Big Bad.
  • Big Sister Instinct:
    • If you don't want Illya to sic Berserker on you, then do not harm a single hair on Shirou's head. Rider finds this out the hard way.
    • As much as Rin might not want to admit it, she has Sakura's back.
    • In Chapter 22, Shirou goes mental on Caster for hurting—and nearly killing—Illya after taking her Command Seals.
  • Big "WHAT?!": Taiga's reaction to learning that Illya is Kiritsugu's daughter.
  • Black Eyes of Evil: Caster Alter's eyes are solidly black, sclera and all. Dark Sakura's eyes become like this when Angra Mainyu fully takes over.
  • Blade Brake:
    • Lancer Alter does this while fighting Berserker, breaking his arm in the process.
    • Saber does it soon after while fighting Gilgamesh. Saber does it again at the start of her fight with Lancer Alter.
    • Shirou does this briefly while being dragged around by a sword on a chain.
    • Saber Lily does this after using Invisible Air for propulsion while fighting Angra Mainyu's shadow simulacrum of Assassin.
  • Blade Run: Saber Lily uses her opponent's weapon as a ramp to knee him in the face.
  • Blood Knight:
    • Lancer Alter's enthusiasm for a good fight makes his uncorrupted self seem almost calm.
    • Saber Alter is one after Dark Sakura stabilizes her.
    • Saber Lily is one, as well. Her first opponent gets stronger every time she cuts it down and the fate of the world is at stake, but she's happy for the challenging fight.
      Saber Lily: So, the smaller unit can also regenerate. Or is it more like the madness becomes entirely new flesh? What a confounding creature you are. I wonder what it will take to make you stay dead?
      Rider: Are you... enjoying this?
      Saber Lily: [confused] Are you not?
  • Breather Episode:
    • After an intense, multi-sided battle on and around the mountain, the heroes go home to regroup. The next few chapters alternate between humor and sharing information, with bits of drama sprinkled in leading into the next buildup of tension.
    • After an action-packed few chapters wherein things go From Bad to Worse multiple times in one night (see entry below), the next chapter-and-a-half consists of comedy with a side of fluff as the remaining heroes make preparations for the final battle. Double Subverted; see Bait-and-Switch above.
    • A tiny episode of more concentrated humor is had during the final battle. Several Servants begin discussing their next move against Avenger until it quickly devolves into displays of ego and insults, and a running gag is revisited.
  • Butt-Monkey:
    • The author loves tormenting Shinji any chance the opportunity comes.
    • Rin to a lesser extent, especially early on in the story. None of her plans go well, she is a victim of the Fastball Special from her own Servant on multiple occasions (see below), and she is constantly being trolled by her enemies and allies alike.
  • Call-Back:
    • Upon meeting Archer again, Gilgamesh refers to a To the Pain promise (see below) he made the last time they met and says it's time to get on with it.
    • Gilgamesh losing a hand becomes important later when Kirei offers it to Dark Sakura and she uses it as a catalyst to transport herself to Gilgamesh's location.
  • Came Back Strong:
    • Saber is corrupted by contact with the Shadow. Then Illya brings out the suppressed good in her, turning her into Saber Lily, a version of her who is now immune to corruption and emotional or psychological attacks.
    • Gilgamesh is turned into his child self just before the climactic battle. At the climax, the light of Avalon and his sensing all the heroic spirits fighting against Avenger catalyzes his transformation into his Fate/hollow ataraxia adult form, which Enkidu calls Gilgamesh's "truest self".
  • The Cameo: Waver Velvet, a.k.a. Lord El-Melloi II, has a discussion with Rin in the epilogue.
  • Cannibalism Superpower: True Assassin has access to the abilities of anyone consumed by the Shadow.
  • Casting a Shadow: Anyone controlling the Shadow is using shadow/darkness magic, but especially Dark Sakura, whose control over it is complete. She can make constructs and creatures of shadow.
  • Casual Danger Dialog:
    • Saber casually remarks while deflecting a barrage of arrows that she believes Archer is attacking them.
    • While they're running for their lives from the Shadow, Lancer asks lightly about Archer's master, says it'd be a waste for a girl that pretty to die, and tells Archer to get Rin and escape while Lancer holds the line.
    • Rin and Archer banter some while dodging a rain of fire attacks.
    • Lancer Alter is talking with Shirou and chuckles while dodging a stray shot from the meteor shower of Babylon.
    • Saber Lily is fighting against Lancelot. It takes every ounce of effort she can possibly put into the battle just to fight evenly with her opponent, but she still banters at him.
    • Shakespeare, Nero, and Tamamo no Mae converse easily in the midst of a battle against an enemy force.
    • Saber Lily complains about not being able to perfectly replicate the Tsubame Gaeshi technique. She dismisses Shirou's warning of an incoming attack, blocks it, and expresses her boredom with the current battle. She asks her opponent if they would please just die already.
  • The Cavalry:
    • After Gilgamesh raises the volume of his sword rain by several orders of magnitude, Saber's defense is beginning to fail. Help arrives in the form of Archer countering the Gate of Babylon with his projections.
    • Each of the remaining Servants is fighting an opponent created by Avenger and at a pivotal moment when they gain or are about to gain the advantage, other fighters show up to save the Servants' respective opponents.
    • Morgan le Fay joins the fight against Saber when Avenger proves unable to overwhelm her.
    • A cavalry arrives to support the protagonists against the Sea of Souls when Illya and Sakura create an ad hoc summoning ritual and summon a veritable army of Servants, including Heracles as Archer, Medea Lily, all the Hassan leaders, and many more, possibly every spirit in the Throne of Heroes.
    • Heracles arrives to support Medea and Atalante against Avenger's concentrated manifestation.
  • Cerebus Syndrome: The first couple of chapters are pretty light-hearted, but there're some dark moments to be found in the story, and increasingly so. It never loses its humor and heartwarming, though.
  • Character Death: Major characters, in order: Fake Assassin, Kuzuki, True Assassin (apparently), Berserker, Zouken, Caster, and Archer.
  • The Chew Toy:
    • Shinji, arguably even more than in Canon.
    • Lancer still can't catch a break, what with his being eaten by the Shadow and turned Alter. Though, the fic does Throw the Dog a Bone several times.
    • Berserker will always die before the route even reaches the climax, and this route is no exception, with him falling under Caster's command thanks to Rule Breaker, and Saber being forced to destroy him in order to save Shirou, Illya, Rin, and Archer.
  • Close-Call Haircut:
    • Illya loses some hairs to a fireball passing her face. This is an especially close call considering she's standing still.
    • Rider loses six inches of hair to a dodged swing from Berserker.
    • A falling boulder apparently somehow cuts a half-inch from Illya's hair.
    • Saber loses a few hairs to her opponent's weapon during the climax.
  • Clueless Chick Magnet: Shirou, as usual. He starts out with Sakura, then picks up Illya and Rin, and then Saber.
  • Cold-Blooded Torture: Kirei does this to Rin, effectively paralyzing her first so she can't fight back.
  • The Corruption: The Shadow does this to Caster and Lancer, rather than devouring them outright as was planned by Zouken. It slowly takes over Saber, as well, after her contact with it.
  • Curse Cut Short:
    • When Caster Alter first sends the Shadow after him, Lancer gets out, "Oh, f—" before he has to start dodging.
    • Saber says, "Oh, sh—" and the rest is drowned out by a roaring wave of prana.
  • Cutlass Between the Teeth: Archer projects Kanshou between his teeth after he loses an arm.
  • Cutting the Knot: The goal is to get into the mountain cave housing the greater Grail. Gilgamesh doesn't have the patience to look for the tunnel entrance and decides to create his own by blasting through the mountain with noble phantasms.
  • Dark Action Girl: Rider. Also, arguably the course for Caster Alter.
  • Deadpan Snarker: Archer has a snarky streak he displays frequently. Rin has one that comes up more toward the end.
  • Defensive Feint Trap: True Assassin flees from Saber into the woods around Ryuudo Temple, letting her chase him to the spot where the Shadow and Lancer Alter are waiting to ambush her.
  • Defiant Captive: Illya is kidnapped, but when she wakes up she calmly asserts that the heroes will save her and argues with her captors.
  • Defiled Forever: Gilgamesh feels this way about Saber and goes to extra lengths to kill her in Chapter 29, claiming that allowing the Shadow to touch her core without his permission is an even worse infidelity than taking a lover.
  • Defrosting Ice Queen: Saber and Illya, in different ways.
  • Deliberate Injury Gambit: Shirou does one when fighting the counterfeit Archer.
  • Despair Event Horizon: Saber Alter feels she's so far beyond redemption that she's not even going to try.
  • Deus Sex Machina: Used once, defied twice.
    • Does happen between Caster Alter and Sakura Matou in Chapter 20, within one of the latter's dreamscapes.
    • Defied in favor of Blood Magic in Chapter 34 by Shirou to Illya and by Rin to Child Gilgamesh, with Shirou being considerate of Illya's feelings (and youthful appearance) and Rin far less respectful towards Child Gilgamesh (the feeling is mutual).
  • Dissonant Serenity: Avenger is incredibly polite, which, given its goal, is off-putting to its opponents. Shirou and Saber note that they were expecting something more monstrous.
  • The Dragon: True Assassin to Zouken Matou, being more powerful than him overall but loyal enough to not backstab him.
  • Dragon-in-Chief / Dragon with an Agenda: Caster Alter is both, to different characters:
    • The former to the Dark Grail, which hasn't enough intelligence beyond its loneliness and hunger.
    • The latter to Zouken Matou, who thinks she is incorrigible but will serve him until he no longer needs her; in reality, she's the one pulling his strings.
  • Drunk on the Dark Side: Servants corrupted by the Shadow most definitely get a kick off the near-unlimited prana it provides. Even Saber isn't immune to its lure.
  • Dual Wielding: Besides Archer's and Shirou's use of Kanshou and Bakuya, Saber dual wields Excalibur and Avalon against her opponent at one point in the climax.
  • Dude, She's Like, in a Coma!: Illya does this with Shirou to help him with his mana deprivation caused by Rider. Multiple times.
  • Dying as Yourself:
    • Just like in the Fate route, Berserker regains his sanity when he is fatally wounded. Before he dies, he warns Saber that she gave in to her hatred and rage to defeat him, and if she keeps doing that, it will consume her.
    • After being fatally wounded by Dark Sakura, Archer projects Rule Breaker and kills himself with it, both preventing the Shadow from corrupting him and dying as Emiya Shirou rather than as Archer.
  • Dynamic Entry:
    • Several fights start with a Servant entering the scene with an ambush attack.
    • Gilgamesh intrudes on the gathering of Archer, Shirou, and Lancer Alter by killing the latter with a projectile Ig-Alima.
    • Mordred interrupts the dueling Saber and Lancelot Berserker by materializing mid-swing and cutting down the latter.
    • Morgan le Fay comes into the scene by firing a massive beam of prana down on Saber and her felled opponents.
  • Earn Your Happy Ending: By the end everyone has settled into a happy existence with Rin and Sakura having secretly arranged to have the latter go and talk to the Einzbern head to let Illya not die young but get a full human lifespan to be with Shirou.
  • The End of the World as We Know It: Avenger is going to wipe out humanity and possibly all life on Earth if it isn't stopped.
  • Enemy Mine:
    • They don't team up, but Saber and Rider halt their fight to deal with Archer, who's trying to snipe them.
    • Notably averted between Shirou and Rin: because Illya chooses not to attack, the Emiya-Tohsaka alliance doesn't form on the first night and they become rivals.
    • Lancer, Archer, and Assassin agree to a ceasefire until they can escape when Caster Alter sends the Shadow after them all.
    • Illya and Saber secretly align on Shirou's side against the other combatants.
    • Rider, Lancer Alter, and Assassin stop fighting and team up in an effort to take down Berserker.
    • An Emiya-Einzbern-Tohsaka alliance is officially established when all parties involved learn about the danger posed by the Holy Grail.
    • Gilgamesh joins the heroes after being betrayed by Kirei, in order to seek revenge.
  • Even Evil Has Loved Ones: Caster towards both her Masters. She truly does care for Sakura's well-being.
  • Even Evil Has Standards:
    • Kirei has an internal monologue about this, comparing himself to Zouken:
      But at the very least, even on those rare occasions that his conscience (yes, despite what anyone else might say, he did have one) flared up, he could always say, "At least I'm not Zouken." The elderly Magus disgusted him, repelled him in every way and on every level. Kirei was, after all, completely selfless in his own way. His means of doing so was bizarre, perhaps, but he cared only for other people.
    • More conventionally, Gilgamesh reacts this way to Caster Alter (and her "pet" shadow monster, Lancer Alter).
    • Though not a case of Evil having standards, Illyasviel mentally compares Gilgamesh's attitude to that of the Shadow. Gilgamesh is found... wanting, due to his conceit and smug-superiority coming off as more contemptible than the Shadow's anguished loneliness.
    • Caster Alter feels the same way about Zouken as Kirei does. She may be evil and steal people's souls, but at least she's not so slimy about it. She also considers Zouken making a puppet doll out of a heroic spirit's corpse, even Assassin's, to be profane even by her standards.
  • Evil Cannot Comprehend Good: Caster cannot understand why Sakura does not want to take bloody revenge against the people who have made her suffer in her life. Kirei eventually lampshades that neither Zouken nor Caster can understand Sakura and explains why.
  • Evil Is Petty: Morgan Le Fay hates Saber/Arturia so much that she would rather let the world be destroyed and everyone die than let Arturia be happy for one second.
  • Evil vs. Evil: Kirei Kotomine, Zouken Makiri, and Caster Alter all have conflicting plans and are therefore against each other. Meanwhile, Lancer Alter just wants to indulge himself in fighting and is perfectly willing to damage the plans of people like Zouken and Caster Alter to get it, even though the latter is supposed to be controlling him and the former is supposed to be controlling the latter.
  • Exploited Immunity: Caster Alter, while controlling Berserker, uses explosive attacks that won't harm him but are intended to hurt his opponent.
  • Explosion Propulsion: Shirou uses Rho Aias to let an explosion propel him and Rin toward their destination and away from the enemies holding them up from reaching it.
  • Eye Scream: Downplayed. Avenger is stabbed in the eye, but its body doesn't really exist. It uses Verg Avesta to make Rider feel like her eye has been stabbed, but it's just phantom pain. Later, Archer Heracles loses an eye several times, but it heals quickly each time.
  • Face Death with Dignity: Berserker does this.
  • Fastball Special:
    • On the first night, Rider throws Shinji into a thorny bush and, hilariously, Shirou throws him into Rin.
    • Archer throws Rin into a thorny bush to get her out of a danger zone.
    • Saber does the same to Shirou on a different night.
    • Rin gets chucked by Archer (again) into a pond. At least it's better than a bush.
    • Although it is by teleportation, Illya and Sakura get chucked in a pond by an ally.
    • Lancer has Heracles throw him at Avenger so he can finish it off with Gae Bolg.
  • Fighting a Shadow: The body Avenger interacts with the group with is merely an avatar, a physical projection of its true existence.
  • Fighting from the Inside: After Saber Alter becomes coherent, she says the reason she was The Berserker at first is because there was a spark of light inside that refused to go out and she was at war with herself.
  • Flat "What":
    • The response of Archer, Lancer, and True Assassin to the appearance of Caster Alter:
      Lancer: What...
      True Assassin: The...
      Archer: [thinking] ...Hell?
    • Shirou responds this way when Illya goes from near-crying to cheerfully calling him adorably shy.
    • Given several times during the Breather Episode in response to things Illya says.
  • Flesh Golem: Caster Alter stitches together parts of the corpses of True Assassin and False Assassin to make a new familiar.
  • For Want of a Nail: The many and vast changes snowball from Shirou responding to Illya in their first meeting and offering help.
  • Friendly Enemy: Rider. Even when she takes some of Shirou's prana to ensure Sakura doesn't die, she's very considerate about it.
  • From a Single Cell: Berserker regenerates from chunks of meat and bits of bone.
  • From Bad to Worse:
    • Caster takes Illya's command seals with Rule Breaker, giving her control of BERSERKER.
    • Archer is exhausted, heavily injured and without an arm from fighting against Gilgamesh, and he still has to fight Saber Alter. As Archer remarks that it couldn't get worse, Dark Sakura appears, having consumed Gilgamesh by use of his previously amputated hand.
  • Future Me Scares Me: This is roughly how Saber Gilles de Rais feels about his Caster version, though it's more of distate and distrust.
  • Glasgow Grin: Assassin gives himself one when he cuts away the stitches holding his mouth shut.
  • The Glomp: Illyasviel glomps Shirou, and to a lesser extent Saber, in the epilogue.
  • Go Out with a Smile: As in canon Heaven's Feel, False Assassin does this when sacrificed to summon True Assassin in order to show contempt for his killer by rejecting an Undignified Death.
  • Godzilla Threshold:
    • When she realizes just how bad things are with Avenger, Illya actually encourages Shirou's return to the fight even though he's still healing, instead of objecting like he thought she would.
    • This also applies to the plan to summon what may be the entirety of the Throne of Heroes to stop Avenger. Illya even notes that such a plan, under normal circumstances, would have had the World strike them down with extreme prejudice even if the effort from the attempt didn't kill them.
  • Gondor Calls for Aid: This is what the mass summoning boils down to; they need aid and call on all the heroes in the Throne for it. Their call is answered.
  • A Good Way to Die: Subverted for Lancer Alter when True Assassin saves him and leads Berserker into the Shadow's grasp.
  • Greater-Scope Villain: Like in the original visual novel, Angra Mainyu is responsible for the Holy Grail's corruption and it influences the Alter Servants and Dark Sakura. However, this time it actually succeeds in manifesting before the heroes can destroy the Grail and it proceeds to take over as Big Bad.
  • Hate at First Sight: This is Illya and Sakura's reaction to meeting William Shakespeare.
  • Hero Antagonist: Rin, as Shirou's opponent during this War. However, they come to an agreement due to the bigger enemy that is the Shadow and the Dark Grail.
  • Heroic Resolve: Invoked in Sakura by Medea to prevent the former from sacrificing herself.
  • Heroic Sacrifice: Subverted. Sakura forces Zouken to kill her in order to prevent the black Grail from forming. However, she's Only Mostly Dead and is convinced to cling to life when Medea provokes Heroic Resolve from her.
  • Heroic Safe Mode: Shirou's body is on autopilot while automatically recovering from a normally fatal wound, and starts fighting on instinct when he sees Illya is captured and has been hurt.
  • Heroic Second Wind: Rider is given the determination and new strength to fight when Sakura tells her to live so they can step into the light together.
  • High-Speed Missile Dodge: Rider dodges a homing sword-arrow by speeding past it. Unfortunately for her, it's a Super-Persistent Missile.
  • Hoist by His Own Petard: Avenger's wearing down of the dimensional boundaries is the only reason why Illya's and Sakura's plan to stop it works.
  • Hope Spot: Shirou has just freed Sakura from possession by Angra Mainyu and averted Angra Mainyu's birth. It seems the trouble is over. Then Kirei stabs Shirou in the back and dives into the sludge leaking from the Greater Grail, starting back up the birth of Angra Mainyu.
  • How Is That Even Possible?: Shirou asks Gilgamesh how he can have unique chocolate in the Gate of Babylon. Gilgamesh boasts that the Gate of Babylon holds prototypes of every treasure, even things that were invented after his lifetime.
  • Humanoid Abomination: When Avenger's core takes as close to a physical form as it can, it has this type of body.
  • Humans Are Flawed: Illya comes to this conclusion when healing Dark Saber, believing that although humans all have dark sides and regrets, it's not all there is to them, and they don't have to let their darker aspects define them.
  • Hydra Problem: Rider, and later Dark Saber-turned-Saber Lily, are fighting a shadow monster manifested from the Grail. Being a mass of curses, when a head or appendage is cut off the curses spill out and create new "flesh", leaving it with even more appendages than before.
  • Hypercompetent Sidekick: Archer seriously gives off this vibe at times, since almost every significant win for the good guys is at least partially due to something he's done.
  • I Am the Noun: When Kirei asks Sakura if she wants the Holy Grail, she replies that she is the Holy Grail.
  • I Die Free:
    • Illya tells Rin that the reason she didn't stop Sakura from leaving on a suicide mission is because for once in her life, Sakura was making her own choice about her life instead of being someone's doll, which Illya sympathizes with.
    • Archer kills himself rather than let the Shadow corrupt him.
  • I Hate Past Me: Rider meets a younger version of herself and expresses her hatred for that self.
  • I Never Told You My Name: Rin has been suspicious of Archer knowing more than he should for a while, but the last straw for her is when he calls the Einzbern Master "Illya" despite Illya having never told them her given name.
  • I'm a Humanitarian: True Assassin is this as per canon. Sakura's version continues this trend by eating Archer's corpse.
  • Impaled with Extreme Prejudice:
    • Berserker gets impaled by multiple weapons from Gilgamesh, not that it does any good.
    • Rider impales Lancer Alter through the throat with her chain-spike, then drags him along by the chain.
    • Lancer Alter gets impaled by a sword from the Gate of Babylon's storm of weaponry.
    • Shirou gets impaled by a sword being held by the Chains of Heaven and dragged around.
    • Sakura impales every single one of Zouken's worms, destroying them and him completely.
    • Shirou is run through by Saber Alter from behind.
    • Played with when Archer is impaled in his right shoulder with so much force that the weapon goes all the way through, leaving him technically not impaled. Soon after, he impales Gilgamesh through the throat with a sword.
    • Shortly after, Archer impales Dark Sakura through the heart with a sword.
    • Gil impales a sword through Saber Alter's throat and out the back of her neck.
  • Implausible Fencing Powers: Saber cuts a mask in half while a man is wearing it without cutting him.
  • In a Single Bound: Saber Alter scales a tall building in a single bound to get to Gilgamesh.
  • In Love with Your Carnage: Although the sight of Saber corrupted by the Shadow offends him, Gilgamesh is also enamored with the display of her power as she wreaks carnage. Later, when she starts taking down the mountain, Child Gil starts to understand what his adult self sees in her.
  • In Spite of a Nail: The narrative uses "Heaven's Feel" as a base for the most part — most likely due to Sakura and Illya's greater prominence in that timeline — so despite many differences and some expanded character roles compared to HF, the storyline plays out like HF with a Spanner in the Works (though some elements are just FSN routes in general): Shirou has some measure of attraction for Sakura; Zouken Matou decides to participate in the fifth Grail War, which leads to True Assassin consuming Fake Assassin; Lancer still has a string of really bad luck, though after he's absorbed he becomes much more competent and independent as Lancer Alter; Berserker is still The Dreaded and a Game-Breaker in the early stages of the story and he dies an antagonist, to show how dangerous the real villains are and because he's too powerful, as well as being under the control of the Dark Grail (in a manner of speaking).
  • In the Back:
    • True Assassin throws a knife through Caster Alter from behind.
    • Lancer Alter tries to stab Saber from behind to start their fight.
    • Shirou tries to stab Lancer Alter from behind while the latter is blocking a barrage from Archer.
    • Saber Alter runs through Shirou from behind.
    • Gilgamesh attacks Archer from behind while Archer's distracted.
    • Archer runs through Dark Sakura from behind shortly after.
    • Kirei stabs Shirou from behind after Shirou releases Sakura from Angra Mainyu.
  • Ironic Echo Cut:
    • Lancer Alter is losing badly to Berserker and doesn't mind at all. Then, the scene cuts to Saber, who is stuck sitting in a tree while bleeding out from severed legs:
      No shame in a death like this.
      There would be great shame, Saber knew, in dying like this.
    • When Illya is kidnapped and Shirou and Rin are fighting the guards on their way to save her, one of her captors expresses doubt Shirou and Rin will reach them.
      Illyasviel von Einzbern: Shirou and Rin can handle anything you have to throw at them. Wait and see.
      Rin Tohsaka: God, we can't handle this.
    • After Saber solves the hydra problem, she heads into the mountain for the next fight.
      She leaped down the pit into the labyrinth, because one should never waste a shortcut, and prepared for her next battle. Arthur or Arturia, there was always a next battle.
      There was not going to be a next battle, if this continued along the path it was currently heading.
  • It's Personal: Rin goes after Shinji for his implied role in Sakura's abuse at the Matou house.
  • Just in Time:
    • Caster Alter calls for Berserker with a command spell just in time to, albeit inadvertently, save Rider from dying to Berserker.
    • Avalon activates in Shirou's soul just in time to save him from being destroyed from the inside out. Then it sends [[spoiler:Shirou to Arturia and activates its barrier function just in time to save Saber from the explosion of power from the Beam-O-War between her sword and Mordred's.
    • Many times throughout the final battle one or more Servants fighting outside arrives just in time to save one or more others.
  • Kangaroo Court: Rin is summoned to the Clock Tower to face a sham trial for the Holy Grail War going so out of control while she was Second Owner of Fuyuki.
  • Killing Intent: Servants can project and sense killing intent. Lancer has immunity to projectiles that is based solely on this, able to easily weave and dodge his way through barrages by detecting killing intent.
  • Knight of Cerebus: Caster Alter facilitates the events that make the Holy Grail War much darker and more serious.
  • Ladies and Germs: Hilariously invoked by Archer in Chapter 3 (albeit non-verbally) when preparing to kill Shirou, Shinji, and their Servants:
    Archer: Good-bye, Ladies and Gentlemen. Well... ladies, gentleman, and Shinji.
  • Lamprey Mouth: The steadily more amorphous monster that causes the Hydra Problem (see above) grows lamprey mouths in various places.
  • Literal Split Personality: Two aspects of the legend of Gilles de Rais are summoned in the climactic battle against Avenger.
  • Living Shadow: Avenger's core, called the Sea of Souls, and the monsters it spawns are this.
  • Locked Out of the Loop:
    • For a long time Shirou has no idea that the sweet little ojou he met in Chapter 1 is a participant in the Holy Grail War. Illya does her best to keep it that way for as long as possible.
    • In the epilogue, Illya asks Rin, Sakura, Saber, and Rider to not let Shirou know that Illya only has a few years left to live. However, Rin and Sakura are working on a solution to stabilize Illya's body and it is implied they will succeed.
  • Loophole Abuse:
    • Shirou's and Archer's spiritual resonance allows Archer to remember a Japanese style of archery that involves emptying the mind of all thoughts. Because this method eliminates his killing intent, it doesn't trigger Lancer's Protection from Arrows skill.
    • Avenger, an avatar of All the Evil in the World, draws its power from the pain and negative emotions of every human in the world. Young Medea gets Shirou to its core, the body of Kotomine Kirei, and Shirou pulls it into his reality marble, which is a world cut off from reality. So, instead of seven billion-plus people, Avenger is only powered by five: Shirou and the few Servants close by. The extremely weakened Avenger is much easier to defeat.
  • Meaningful Echo: Subverted. Saber Lily suddenly bursts into the cavern through the ceiling, and Shirou is reminded of the night he first summoned her: he's once again on the ground, facing his impending death from an enemy, and he's just as surprised and awestruck to see her now as he was then because he didn't know she'd been freed from her corruption. Making the comparison, he imagines her turning to him and saying the same line as back then: "I ask of you, are you my master?" Instead, she turns to him and starts berating him and teasing him.
  • Mêlée à Trois: Between Archer, Gilgamesh, and Saber Alter.
  • Mercy Kill: Rider is prepared to do this to Sakura if she cannot be saved.
  • Mind Rape: What EMIYA Alter inflicts upon Shirou when Unlimited Lost Works hits him. It overwrites Shirou's reality marble with the most corrupt version possible, in reverse of what Archer did, as the pinnacle of Shirou's craft.
  • Mistaken for Pedophile: Shirou at various times, much to his chagrin. Early on, he's only worried about looking like the time he spends with Illya is sketchy; as they walk around his neighborhood, he notices people giving him disgusted looks and whispering to each other. But, upon finding out that she's actually nineteen years old...
    Shirou Emiya: It means all those innocent things she did! Silly kid stuff! They weren't innocent, Tohsaka! They were... they were... she was... those were dates!
The people he's talking to mistakenly think he's saying he's shocked at her age and thought he was going on dates with a little girl.
  • Mix-and-Match Weapon: Avenger summons EMIYA Alter from Fate/Grand Order, who uses modified versions of Kanshou and Bakuya that are also guns.
  • Morality Pet: Shirou becomes one for Illya, much to her chagrin.
  • Motive Rant: Dark Sakura exposits at length about what she's planning to do and why when trying to convince others to join her.
  • Mouth Stitched Shut: Caster Alter sews Assassin's mouth shut when she "rebuilds" him.
  • Mutual Kill: Gilgamesh finishes off Avenger with Ea, but is caught in the explosion and vaporized as well.
  • My Friends... and Zoidberg: Taiga in the epilogue. Whereas Illya is described as an "acquired taste" by Shirou and Saber, Taiga is one that everyone "has yet to acquire." She tends to barge into Rin's home to eat all the food, bother Shirou, make him pay for her groceries, get into arguments with Rin when she gets indignant about all this, and challenge Saber to hopeless fights.
  • Mythology Gag: Many of the Servants Illya and Sakura summon to stop Avenger are from other Fate/ works.
  • Near-Villain Victory: Avenger is birthed and is just about to succeed in covering the world in a cloak of darkness that will then absorb all of humanity's souls. It gets as far as spreading over all of Japan despite an unparalleled effort by the cavalry to halt its progress, before it's finally defeated at the last second.
  • Normally, I Would Be Dead Now: Illya notes that the extreme situation, her and Sakura's unique abilities, and Avenger's weakening of the barriers between dimensions is the only reason their mass Servant summoning had a chance of working, and that the World would have smitten anyone who tried such a thing under normal circumstances.
  • No-Sell:
    • Rider removes her mask and attempts to turn Berserker to stone with her Mystic Eyes of Petrification. It doesn't work.
    • In order to be purged of the Shadow's influence, Saber has to acknowledge that she's human, darkness and all, and accept the best and worst parts of herself while deciding not to follow her darker impulses. When the Shadow tries to take over her again, she's immune to it because all it does is bring out the darkest side of someone and she's already embraced that side as part of her.
  • No Social Skills: Illya is clever, but her isolation and lack of any real friends throughout her life means that she's not very graceful in certain social elements; she seems to assume that Shirou knew he was going on dates with her despite thinking she was ten and that even if he didn't realize it, it was perfectly acceptable. Whichever one it was, Saber and Rin ultimately get the wrong impression.
  • Noodle Implements: In Chapter 1 (not counting the prologue), Illya and Rin vaguely contemplate expressing their anger at the one perceived to be responsible using "power tools" and "a variety of bladed instruments," respectively.
  • Not What It Looks Like: When Shirou freaks out about the fact that he was, essentially, going out on dates with Illya, Rin and Saber mistakenly assume that he knew they were dates and that he's freaking out because he didn't know she was nineteen. Of course, Shirou's inability to connect with people and empathize properly means that he didn't even realize that Illya considered them dates; he thought that he was in an Intergenerational Friendship and misread Illya's intentions, which then leads to her digging him in even deeper in an attempt to save him. A long, heated discussion ensues offscreen for twenty-four minutes before the matter is resolved.
  • An Offer You Can't Refuse:
    • True Assassin, on behalf of Zouken, tells Sakura to return to the Matou house and implies that if she refuses, harm will come to Taiga and the archery club members.
    • Zouken offers to Caster Alter for them to work together, with her working under his orders. When she laughs in his face, he demonstrates that he can kill Sakura at any time, which will make Caster Alter disappear.
  • Offhand Backhand: Saber Lily multiple times swings her weapon and without looking cuts down an appendage or head of the monster she's fighting. During a later fight Medea hangs a lampshade and Saber Lily questions the idea that she would need to see an attack to block it.
  • Offscreen Moment of Awesome: Saber takes down five constructs mimicking knights of the Round Table, all of whom would be top-tier Servants, in her time offscreen since the third one was mid-creation.
  • Oh, Crap!:
    • When the Shadow first appears, Archer quickly realizes that the war he's currently in is not the same one he originally dealt with when he was alive.
    • Anyone during their first encounter with a Shadow-corrupted Servant, even Zouken.
    • Lancer Alter when he sees Berserker getting absorbed by the Shadow, because it means their fight is over.
    • Rider when she fails to turn Berserker to stone.
    • Archer and Caster Alter when they see the Gate of Babylon raining death upon them.
    • Illya when she realizes that Sakura plans to merge everything on Earth with Angra Mainyu and send it into Akasha, effectively making it God.
    • Rin is horrified when she realizes Kirei is a genuine follower of Dark Sakura and not just working some secret plan.
  • The Ojou: Before he learns her name, this is how Shirou addresses Illya.
  • Only Mostly Dead: Sakura's Heroic Sacrifice is subverted this way.
  • The Only One Allowed to Defeat You: Mordred claims she didn't miss Saber Lily but was aiming only for Lancelot, because she doesn't want to share credit for defeating her father.
  • Or Was It a Dream?: Caster's attempts to corrupt Sakura via illusions projected into her sleeping mind.
  • Other Me Annoys Me:
    • The normal Rider Medusa and the Lancer Medusa summoned as a minion of Avenger hate each other.
    • The same applies to Saber!Gilles towards Caster!Gilles.
  • Pinned to the Wall: Archer pins Saber Alter to the ground with as many swords as he can control at once.
  • Poor Communication Kills: Inverted. Shirou, who usually dismisses any weirdness or possible ulterior motive he might notice in Illya's actions, at one point stops her and makes her confess to him in full what she wants them to do and why, avoiding any dramatic misunderstandings.
  • Post-Kiss Catatonia: Shirou is briefly thrown into this by Illya's "Shut Up" Kiss.
  • Precision F-Strike:
    • Lancer's is cut short when Caster Alter deploys the Shadow to attack him in earnest.
    • Archer gives one when he sees Rin, Shirou, and Illya are all down and he has to try to fight Berserker without hurting them further.
    • Lancer Alter does it when expressing his loathing for Archer after Archer insults him on the Emiya estate's roof.
      "... You know, I usually like to chat with my kills for a little bit, but I think in your case I'm just going to rip your fucking head off."
    • Rin's response to hearing about Zouken's demand to the heroes is, "Oh, fuck that."
    • Sakura's response to the suggestion that she and Illya can't do anything to help in the final battle and have to just watch is, "Well. Fuck that." It's all the more poignant because it's Sakura.
    • Saber gets frustrated enough with the heroes' inability to kill Avenger that she says, "Bloody hell," to Shirou's great shock.
  • Precision-Guided Boomerang: Archer exploits this property of Kanshou and Bakuya in battle, even setting up traps by planting them in the ground.
  • Protectorate: Shirou is this for Illya after he's nice to her the first time they meet.
  • Punctuated! For! Emphasis!: Rider declares her intent to kill Avenger, and when it's brushed aside she repeats herself one word at a time.
    Rider: You. Harmed. Her. And. I'm. Going. To. Destroy. You. Don't question it again.
  • Pure Energy: Dark Sakura can summon semi-solid creatures of pure mana.
  • Rage Breaking Point: Rin reaches this when she comes to understand everything that Sakura went through growing up in the Matou household.
  • "The Reason You Suck" Speech: Shirou (of all people) gives one to Shinji in the first fight of the war.
  • Red Eyes, Take Warning:
    • Sakura's irises turn red soon after she becomes Dark Sakura.
    • The monsters made of curses summoned by Avenger are evil and have red eyes.
  • Revenge:
    • After Kuzuki's death, this becomes Caster's motive.
    • This is Gilgamesh's motive for joining the heroes' team. He gets it when he's the one to finish off Avenger/Kotomine once and for all.
    • Morgan so badly wants revenge on Arturia for spoiling her plans that she'll side with Avenger to make it happen.
  • Rousing Speech: Archer Heracles gives one as he leads the cavalry against the Sea of Souls.
  • Running Gag: Servants keep throwing their Masters into bushes and water to get them safely out of the way.
  • "Save the World" Climax: The plot is initially contained to winning the Holy Grail War in Fuyuki City, but by the end of the story has expanded to saving the world from a threat.
  • Screw the Rules, I Make Them!: Kid Gil says that Gilgamesh never did anything illegal because of this trope.
  • She's Back: Saber, upon being purged of the Shadow's corruption by Illya, makes a glorious Dynamic Entry into the middle of Rider's fight with the shades of True Assassin and Caster's dragon — as Saber Lily.
  • Sheath Strike: Saber dual wields Excalibur and Avalon against her opponent at one point in the climax.
  • Shout-Out: Sakura's first dream sequence is a huge one to Baldur's Gate II.
  • "Shut Up" Kiss: Illya kisses Shirou in order to derail his anguished train of thought over not being able to save everyone from the attack on his neighborhood.
  • Slasher Smile: Gilgamesh sports one of these after the perceived insults to him pile up enough, particularly the growth of the Shadow. It is unnerving enough to scare Kirei.
    Gilgamesh turned to face him, and Kirei felt a slight twinge of fear for the second time. Gilgamesh was smiling. Widely. Ear to ear, an expression of almost childish happiness, but something in his eyes...
    Gilgamesh: It seems I smile when I'm truly angry.
  • Squick: In-Universe.
    • Illya and Saber are both disgusted by Saber having to drink Illya's blood to allow a prana transfer. Illya mentally calls it icky.
    • Rin and Archer have to hold back from physically gagging when they see Illya kiss Shirou.
  • Staircase Tumble: Rin throws Shinji down a flight of stairs in the school.
  • Stealth Hi/Bye:
    • The effect is somewhat lost because Shirou has come looking for him, but Kirei pulls a Stealth Hi when he somehow appears behind Shirou at the church.
    • Robin Hood says hi from where Achilles is sure there was no one a second earlier.
    • Zelretch speaks up from a seat that Rin swears was empty five seconds earlier, presumably through use of the Kaleidoscope.
  • Super-Persistent Missile: Archer projects Hrunting, a sword whose concept of "not stopping until it hits its target" is somewhat useful in melee combat but extremely useful when it's used as an arrow, and sends one after Saber and then another after Rider.
  • Superpowered Evil Side: Servants who are absorbed by the Shadow come out tainted by its evil influence and boosted by its infinite mana supply.
  • Sword Beam: Saber Alter has been boosted by her link to the Shadow to the point that even her regular swings can emit sword beams.
  • Sword Plant: Saber tends to stab the ground and use her sword for support when she's exhausted. Archer sometimes plants Kanshou or Bakuya in the ground to set up a trap exploiting their attraction to each other.
  • Sword Sparks: This frequently happens during the fights that involve melee combat. At one point sparks are the only indication anything is happening, when True Assassin throws black daggers, invisible in the night, at Shirou and Saber's invisible blade deflects them.
  • Sympathy for the Devil: Shirou almost feels sorry for Avenger when Gilgamesh is destroying it for good.
  • Take That, Scrappy!: Invoked by the author in regards to Shinji, whom he admits to despising—apparently, making him suffer is a joy for him. Not that anyone really minds.
  • Tears of Blood: Mordred begins crying tears of blood as she is corrupted further by Morgan le Fey's magic.
  • Teeth-Clenched Teamwork:
    • Archer, Lancer, and Assassin agree to work together and not try to kill each other until they've escaped a mutually dangerous situation.
    • Rider, Lancer Alter, and Assassin stop fighting each other and work together in an effort to kill Berserker.
  • Tempting Fate:
    • Caster Alter declares that there will be no more last-minute rescues to stop her from killing Shirou. Immediately after she says so, Rider breaks down the front wall of the room they're in. Zouken hangs a lampshade.
    • Archer, facing down against Saber Alter after tying with Gilgamesh and severely injured, tells himself that things couldn't get too much worse. Then, Dark Sakura shows up.
  • That Man Is Dead:
    • The fully corrupted Saber sees herself as being a separate person from Arturia and desires to cement this by killing everything that tied the old her to the modern era.
    • Saber Lily claims Avenger's tactic meant to cause mental duress won't work on her because the version of her who would be affected by it is dead and gone.
  • There Was a Door: Dark Sakura says this to Rin when Rin and Shirou break through a wall to enter the villains' lair.
  • This Is Gonna Suck: Lancer says it, word-for-word, when preparing to take on the Shadow and Caster Alter.
  • To the Pain: Gilgamesh graphically describes how he will torture Archer as punishment for copying his treasures and says that's only the beginning.
  • Tranquil Fury:
    • Archer manages to anger Gilgamesh to the extent that the latter goes from roaring in rage to speaking softly while promising to inflict untold torments on Archer.
    • Archer quietly and calmly resolves to torture Caster Alter to death upon seeing Illya being held hostage and the fear and pain she's in.
  • Undying Loyalty: Rider to Sakura, as per canon. Also, Caster Alter to Sakura.
  • The Unmasqued World: The final battle ends up exposing the existence of magic to the public. Though most civilians like Taiga are still trying to wrap their heads around it, the Mage's Association are going crazy and fear they will be doomed.
  • Utopia Justifies the Means: Dark Sakura believes she's going to create a utopia, even if it means assimilating everyone into Angra Mainyu and heading to the Root.
  • Villainous Breakdown:
    • Dark Sakura initially is in control of Angra Mainyu's influence over her and is still calm and kind even while working toward an evil goal, but she loses control when Shirou manages to activate his own version of Unlimited Blade Works and becomes a mindless rage machine.
    • Avenger initially has an eminently calm persona, but loses it when Illya and Sakura summon the entirety of the Throne of Heroes, and not only does it find itself being halted, but driven back.
  • Voodoo Zombie: When Servants die to the Shadow, its controller can call them back out to serve him or her.
  • Wave-Motion Gun: Morgan le Fay fires a massive beam of prana down on Saber and her felled opponents.
  • We Can Rule Together: Dark Sakura tries to convince the heroes and the corrupted Saber to join her side. They all refuse, with Saber Alter outright declaring her intent to kill her.
  • Well-Intentioned Extremist:
    • Dark Sakura seems to believe her actions to be in humanity's best interest.
    • Avenger considers itself an ally of humanity. It intends to wipe out humanity in order to fulfill their collective wish for a greater power to be the cause of their suffering. Even when it starts losing ground, getting pushed back, it rants a bit about the champions of light being enemies of humanity as a whole.
  • Wham Episode:
    • Chapter 8.
    • Chapter 21 tops it. Caster Alter now has control over Berserker after using Rule Breaker on Illya, Saber is missing her legs, and Shirou had a hole blown through his chest.
    • Chapter 22: Rider nearly dies fighting Berserker, she teams up with Assassin and Lancer Alter to stop him... and Lancer Alter kills Assassin in revenge for an earlier slight. Shirou draws on incredible power to protect the now-defenseless Illya from Caster Alter and injures her. Saber is able to pull beyond her reserves and destroy Berserker to protect Shirou, Illya and Rin... but only because she somehow drew on some of the Tainted Grail's power. And Caster Alter is smiling at this last bit.
    • Chapter 27: Zouken has Caster's minions kill everyone in Shirou's neighborhood and then set their houses alight, unleashing Caster Alter to distract Saber and Lancer Alter to deal with Archer, and then tells Shirou this is his idea of a peaceful negotiation. If he doesn't hand over Illya in four hours and have the Servants feed themselves to the Grail, he'll recreate the Fuyuki fire on a larger scale.
    • Chapter 31: Caster ends up converting Sakura to her Dark state to save her life, only for Dark Sakura to absorb her and Zouken and decide to work with Kotomine to birth a dark god.
  • Wild Card: All of the corrupted Servants have their own agendas and are perfectly happy to mess up the plans of their "masters" to get them.
    • Caster Alter wants Sakura to embrace her inner darkness and in doing so get revenge on everyone who has wronged her.
    • Lancer Alter wants to fight and kill until either he's dead or everyone else is, and is perfectly happy to screw up Caster and Zouken's plans in order to get the war he craves.
    • Saber Alter wants to take revenge against the system which she wasted her life on and become a new person; i.e., she wants to destroy the Holy Grail and everything and everyone associated with it. This includes Dark Sakura, whom she regards as another enemy.
  • Won't Take "Yes" for an Answer: Downplayed. Shirou expects to have to fight Illya tooth and nail over him rejoining the fight. As he's gearing up for the argument:
    Illyasviel von Einzbern: You're going to have to go back into the mountain.
    Shirou Emiya: Illya, I'm going to... wait, what?
  • Woobie, Destroyer of Worlds: Dark Saber and Dark Sakura. Illya considers it a better result than someone more malicious getting the Dark Grail's power.
  • "World of Cardboard" Speech:
    • Illya gives an internal monologue to this effect on the night of the first fight, regarding Shirou.
    • Lancer Alter later gives one.
      Lancer Alter: Fallen? Saber... you know who I am. I spent my entire life desiring battle. Glory. And I spent each and every bit of it as someone's damn lapdog. The Hound of Chulann... but oooooh, things are different now! My new Master runs only on instinct. It has no goals, it's just a monster that wants to feed, to hunt and kill the Seven Servants. To face down each one, defeat them, and devour them. That's all it wants to do, and all it wants me to do. And I can do it however I want, with my so-called Master too mindless to do anything about it but follow me in a frenzy, begging for scraps. I don't have anyone holding me back, Saber. Nobody's leash stopping me from claiming the ultimate battle that I always wanted.

      Fallen? For the first time in my life, I'm free!
    • Illya does this later to Dark Saber, pointing out that her rampage is illogical and petty.
  • World of Silence: Avenger's goal is to create one.
  • Worthy Opponent:
    • Gilgamesh decides that contrary to his first impression of her, the corrupted Saber is a worthy opponent deserving of his full power.
    • Saber Lily views the amorphous eldritch abomination that has evolved from a hydra problem as a worthy foe.
    • Enkidu displays deep respect for Gil's being and his combat ability.
  • Wrong Name Outburst: When Archer Heracles offers to sacrifice himself to hold off Avenger, Illya becomes upset and accidentally calls him Berserker.
  • Wronski Feint: Rider passes over Saber to put her in-between Rider and the sword-arrow chasing her.
  • You Shall Not Pass!:
    • Lancer stops to hold back the advancing Shadow in order to insure Archer's and Rin's escape, though he intends to not sacrifice himself in the process.
    • Some of the Servants summoned by Illya and Sakura are summoned at the edges of Japan to hold back the Sea of Souls from expanding over the ocean to reach the rest of the world.
    • Archer Heracles goes to hold off the beast created by Avenger so that Medea Lily can get Illya and Sakura to safety.

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