The Multiverse is such a wide concept you can just be about anyone in an infinite amount of universes. Chaldea summons alternate universe counterparts of servants. Plot-based story

The Absolute Evil wanted to be born. The hollow child wanted to survive. One of them had to go. In a twist of Fate, the boy remained. This is the story of a Holy Catholic who was saved by Absolute Evil. (Shirou 'Kotomine', Fem!Gil, Salter, Nightingale, Jalter, TYPE-MOON events, M for Mature themes)

Einzbern fell with Illya's failure to win the Fifth Holy Grail War, allowing scavengers to claw at Einzbern's tomb. One of the few remaining Einzberns now turns to the last of her family's former allies, hoping to averting a mad plot that could destroy the world. But with Sakura Tohsaka also known as the Murderer Blue, will it be enough to save the world? Sequel to Peaceful Days.

Kirei Kotomine, at the temptations of Gilgamesh, gave in to his dark desires and caused a flood of death and tragedy. But, what if he didn't give in and remained true to his ideals? A cavalcade of changes would follow. The birth of the makeshift family of Kirei, Rin, Sakura, and Caren. Another makeshift family of Artoria, Irisviel, Illyasviel, and Gray. This is a new Fate.

Fate is a fickle thing, especially when two dimensions clashes and a young Master learns that she has more to her plate than she initially expected to have. Continuation to: Tale of Two Kings (Redux) - Servant!SI - Master!Artoria

Winning the Holy Grail War took a terrible toll on each of the participants - especially Illya. As a Hero Of Justice in training, Shiro is determined to help. But when he tries putting the power of Bladeworks to a use for a new purpose, it has some unexpectedly large results!

Ritsuka Fujimaru was just a normal person some months ago and now he's fighting to save humanity by traveling through history. Not only that but he also encounters two kids who want to know the origin for why they're far from home. An alternative version of FGO Observer on Timeless Temple.

Counter Guardian Emiya is a man of many regrets. Among them, the fact that he wasn't able to save his Saber when he was a boy continues to haunt him to the end of days. Now, however, a chance has mysteriously appeared to change that result. And being the practical man he is, he will not hesitate to seize it. But still... why in Alaya's name is Artoria his new Master in this world?

An AU where Sakura is not the Master of Rider. Things get odd. The ending is planned, and will hopefully be published soon; the story will continue on AO3. (apparently FFN deletes the first part of the url so just search for "Worm on the Hill of Swords", or Imprimatur13 on AO3). It will not be updated any further here, due to FFN's policies regarding sexually explicit material.

For each Master, a Servant. For each Servant, a Master. The relic system was never introduced, and every Master in the Grail Wars has always received a Servant based on their own personality alone. Now, the Magus Killer goes to war - and receives his greatest weapon yet. But even with all of Assassin's skill and treachery, can they stand against the raw power of the Fourth War?

Mordred meets a certain redhead that saved her from a tyrant trying to burn Camelot. OR, what happens when "Shirou Emiya" gets dropped in 6th century Britannia

Year 2044. Leylines around the world have begun to run dry. As magi desperately attempt to preserve their way of life, an invitation is received: "I am Satanael, First of the Fallen, and he who shall shatter the shackles of Law and Order which weigh down Humanity" A final chance to restore the leylines. A final chance to see a wish realized. (A sequel to FATE Scattered Fragments)

Héroes de cualquier tiempo y lugar, todos reunidos en un solo lugar ... El Trono de los Héroes!

Shirou Emiya, born to a Clan following the name they had not officially been called in centuries, chasing after a dream created by their ancestor as relentlessly as any other Magi family reaches for the Root. This is the boy that Kiritsugu Emiya and Irisviel von Einzbern find in the rubble and mud of the Fuyuki Fire, and this is the boy that they adopted.

A retelling of the fifth Holy Grail War in which Rin summons Saber as her servant instead of Archer. It is a mixture of the "Heaven's Feel" route from the original game and original plot elements. This version of Fate/Stay Night focuses primarily on Rin and Saber's relationship and what could have been.

AU, future. Magic is controlled by computers. The system allows to summon Servants, but their only purpose is to fight on the Arena for the prestige of the richest families of magi... Until the day when the system suddenly crashes, leaving unaffected only the weakest magus, descendant of a certain nameless hero, and her six Servants. Will they fix the situation and save humankind?

After an unfortunate meeting against an unstoppable force of nature that ended in his death, Shirou is reincarnated into another world. Warning: Massive Alternate Universe and Chaotic Crossovers

As Chaldea makes their way inside of the Sixth Lostbelt, they get trapped inside the memory-erasing Nameless Forest. Ritsuka, suffering from the amnesia caused by this forest, ends up close to one of Morgan's patrolls, who are given orders by the Queen to recover this lost human.

a boy named Shirou however a mysterious awakening of his "true self happens and now it's up to him to deal and transition in to the change UBW canon is the followed canon btw"

A collection of one shots and omakes for Fate/Starry Night. Can range from the very serious to the very silly.

La vida de dos hermanos es interrumpida cuando algo les ocurre a sus juegos del Grand Order. Zelretch se presenta ante ellos con una oportunidad única en la vida: Volverse masters de Chaldea. Ahora deberán recorrer las singularidades para rescatar a los servants que han sido corrompidos por una extraña razón y seguir la historia ¿podrán hacerlo?

¿Realmente podemos estar juntas?

Katashi Honda, a struggling street magician needs a change in his fate. Unknowingly to him, he will become involved to the world of magi and servants, and will have to survive however he must, in unorthodox ways. This is the tale of Honda the Warlock!

Ritsuka wouldn't call himself a narcissist exactly. He was confident in his looks, of course, but the normal amount. And besides, it wasn't like his very first instinct upon dreaming of who was essentially the female version of himself was to bang her. No, no, that happened later. (Lemon)

A man gets launched into medieval Britain into the body of the Knight of Treachery. He/She tries to change their destiny of being killed by their father. (Self Insert) (SI) (Update: Chapters 1E and E7 were added to the first arc.)