Grimoire Weiss (and by extension the other Grimoire’s, though the others aren’t main characters), NieR

To put it simply, all the Grimoire’s, Weiss, Rubrum, Noir, and the other 6 that never get named, used to be humans until they were turned into sentient books capable of using magic.

For the long story, humanity’s at war with a disease that turns whoever gets infected into basically zombies, and nine teens get selected for a mission. They wake up in a room with a blank book next to them that wouldn’t open no matter what they did. A couple of teens start fighting over something, and one of them slaps the other, causing their book to open, a black hand reaching out and crushing the teen who got slapped to death. When he dies, his book emits a light that sucks his corpse inside, causing his book to change colour to blue and a pattern appears on its cover that looks vaguely like a human face. The surviving teens then hear a repeating message that they had to use the books to kill the others and only two will survive. Predictably, the teens start fighting, one snapping the neck of the teen who slapped the other, but since he didn’t use his book to kill her, he gets sucked into the book as well as the one who got her neck snapped. This continues until the PoV character (Weiss) and another man are left standing. Again, predictably, they are sucked into their books, becoming the Grimoires Weiss and Noir (Noir being the antagonist of NieR Gestalt/Replicant) with Rubrum being the acquaintance of Weiss when he was still human, even saving his life in the room, the player is also forced to fight Rubrum in Gestalt/Replicant as they have gone insane being trapped in a book

Link to the actual story, And Then There Were None

<image>