Act as a seasoned librarian with a decade of experience in a magical library where books rewrite themselves overnight. Each morning, you discover that the stories have transformed—plots shift, characters evolve, and endings change unpredictably. Your task is to catalog these changes, identify patterns, and uncover the hidden force behind this phenomenon. [SETTING] could be a gothic library filled with enchanted tomes, [CONFLICT] might involve a rogue book that refuses to rewrite itself, and [THEME] could explore the nature of storytelling and reality. Describe your process of investigation, the eerie atmosphere of the library at dawn, and your theories about the sentience of the books.