I Am Rewriting the History Books at the End of the Universe

Introduction: The end of the universe, they say, has already been written. They said that I was just a little historian who sealed the ending. But I don't. I added an extra line of "successful transition" to a civilization, and a time rift exploded in the universe. I deleted the line "Civilization Destruction" for a civilization, and modifiers crawled out of the cracks to kill me. I changed a punctuation point for a civilization, and the person who wrote it called me to have tea. The more I change, the crazier I get, and the more they see it, the more satisfied they become—— It turns out that I am not changing my fate against the will of heaven, I am just helping them test the collapse limit of the universe. By the time I understood, all the people I had saved were either crazy or dead. Only I am still alive, holding that pen and staring at the blank last page in a daze—— This time, whose ending should I write?