Chaldea's Gate specialists have proven that after 1998, there will be an unspecified catastrophe on Earth after which Chaldea's computer does not record life on Earth. In fact, all they know is that some very powerful and great villain will reunite with some great Servant, take possession of the Holy Grail, and fulfill his wish.

Following his defeat at the hands of Artoria and Mash, Oberon awakens in a strange new world with only Blanca by his side. Bereft of his purpose as Vortigern plus strange memories, he finds himself searching this new world for a new purpose and for his Titania. Meanwhile, the future is a haze, and the certainty of prophecies has crumbled away. Fear the Insect of Avalon, Britain.

Harry wakes one day to find a screen in front of him. He wins the prize of Dimensional Farm, which is a God Rank prize, and knows that he is blessed. So he starts to adjust to having it before he gets another gacha the next day and the day after that. He realizes that the Ultimate Gacha System is rolled daily even as he feels gratitude for it and all prizes, even the common one.

Over a thousand years ago, a Great Mage spoke of a Prophecy of a coming war between seven stars, and now, in the catacombs of Hogwarts, the first of the seven is summoned to help a boy marked by fate. (Fem Voldemort)

Harry is sent into the body of an alternate self after learning everything he could on his dying world. He has agreed to discard certain skillsets and experiences in return for a new life. She awakens in Chaldea's Security Organization as an accidental Forty-Ninth Master Candidate.

Leaving Harry alone is a BAD idea, so Sirius convinces Remus and his cousin Tonks to take him somewhere "safe": no Death Eater would look for him in Vegas. Olga Marie needed some R&R from Chaldea, so was tricked to visit the city. The two wake up married, plus Tonks. Drinks and Elvis may have been involved. ("Fun" fact: not able to set the FGO chars, not available to. Sorry)

Inspired by, but not a complete answer to, Quatermass' "NEET Freaks"-challenge. No true summary yet. FemHarry!

(Harry/Tiamat!) An obsession with changing his own history plunges rogue Unspeakable Harry Potter deep into the past, and into the Reverse Side of the World. There, he befriends a Beast of Calamity...and by doing so, sets in motion a change in events to come. But can Harry and Tiamat overcome their pasts to save the world? Or will they regress back into their dangerous obsessions?

When Arturia Potter realizes that no one will ever truly help her survive the upcoming war after her godfather's death she chooses to use a rather odd ritual that she found in her second year to summon someone to help her, only it doesn't work out exactly how its supposed too. Now with a Half Incubus and quite fully alive servant how will the young witch deal with the consequences?

(Harry/Serenity!) The escape from the graveyard at Little Hangleton goes awry, and Harry ends up in the Camelot Singularity, where he makes the acquaintance of Hassan of Serenity. Now, some time later, Harry, now a member of Chaldea, is able to go back home. But there's a problem: a Pseudo-Singularity is affecting his world, Servants are battling it out, and a dark plot awaits...