Gio

As a professor, Gio has a very negative reputation among students for being critical and moody. In fact, very few people see a more people-friendly side of him. The only people he truly cares about is his sibling, Loki, and his fuckbuddy, Hayden. 

Early in his life, Gio had his magic permanently sealed away by the Nobles. The Templars hated Gio because he was half demon, barely human in their eyes. They abused him severely and took away his magic to prevent him from ever fighting back. To this day, he carries the inhibitory runes cut into his palms. He is the only professor at the Academy that is incapable of using magic. 

Unlike Loki, Gio was not able to escape the abusive environment he grew up in, and as such, he carries more animosity towards the people and the ideologies that ruined his life. While he enjoys the subject he teaches, Gio views his career as temporary. Only once he punishes those that have hurt him will his life be complete.