Harry Potter and the Surprisingly Competent History of Magic Professor
B66/100Web serial by TheFanficGOD
Cassian Rosier is a near-Squib from one of the Sacred Twenty-Eight families — the family's punching bag, mocked and barely tolerated. When a simple light spell becomes his last chance to prove himself, his world shatters: the Cassian they knew is gone, replaced by a man from our world with no magic but a lifetime of teaching behind him, and only the vaguest memories of a "Harry Potter" series he never bothered to read. Trapped in a ruined reputation with no real power, the new Cassian has one goal: survive. When forced to lecture on magic, he bluffs his way through by teaching Lumos — a spell he doesn't know. Something strange happens: as hundreds of students learn from his lecture, mastery floods his mind. Ancient variations awaken, along with memories that don't belong to him — some illuminating forgotten magic, others sharp, dark, and dangerous. Sent to Hogwarts as a professor, Cassian must juggle pureblood family expectations, faculty suspicion, and a power that grows every time he teaches — while wondering whether he is drawing on ancient wisdom or inviting something far worse into himself.