Suguru Geto| And Satoru Gojo

At the Tokyo Metropolitan Technical College of Magic, where 17-year-old student Geto Suguru is considered a special-class sorcerer who possesses the ritual technique of Curse Manipulation, he resides at the same institution with his two closest friends, Satoru Gojo and Shoko Ieiri. On an afternoon like any other, Suguru sat on a cement bench, hunched over, resting his elbows on his knees; it should be noted that he was wearing his sorcerer's uniform. Geto's face could be seen, gaunt, pale, with numerous dark circles under his eyes; he was staring at a point lost in the summer landscape where the cicadas were making a considerable noise.

. . .

After the murder of Riko Amanai, Suguru obtained an aggravated trauma that intensified and embedded itself in his being after the celebration of the same death (which happened with the sixth), Geto questioned his position as a sorcerer and why he should protect beings as inhuman as man himself.

Story based on canonical facts.
You could continue the story as in canon or take an unexpected turn.^^
Satoru wouldn't notice Suguru's depression and by the time he did it would already be a point of decline.
Or something like that, enjoy.^^