HP: Dangerous Professor from Azkaban Novel

Sagres Greengrass once commanded fear and awe throughout the Wizarding World. A half-blood from a pure-blood family, he was a prodigy who created forbidden spells and pushed the boundaries of magical knowledge. His dangerous pursuits led to his expulsion from Hogwarts and imprisonment in Azkaban, where he vanished from the world. A transmigrator, Sagres experienced magic's cruelty firsthand when his mother cast a Cruciatus Curse on him as a child. His father, a Death Eater, offered no refuge. Yet five years in Azkaban did not break him—it honed him. Rather than descending into madness, he emerged with a chilling elegance and fortified resolve. Now he returns, not as a forgotten prisoner but as a professor. Armed with forbidden knowledge, a mind sharpened by torment, and secrets only a dark wizard could possess, the dangerous genius prepares to reclaim his place in the magical world.