HP: Outstanding Graduate of Azkaban

[HP Fanfiction] [No female protagonist] Sagres Greengrass is a time traveler. As a member of a pure-blood family in the magical world, his first experience of magic came from a Cruciatus Curse cast by his mother. When he wanted to seek help from his father, he found out that his father was a Death Eater. In the fifth year after being expelled from Hogwarts, Sagres walked through the salty mist of the North Sea and returned to the ancient castle as a professor. Imprisonment in Azkaban did not leave him with madness and corruption, but rather a kind of chilling elegance.