Character Analysis
Mr. Garmes feels guilty.
That's really all there is to his character. He's in the film to have a guilt complex, foreshadowing John Ballantyne's guilt complex. He thinks he killed his father, which gives Constance a chance to explain how guilt complexes work. It also gives Ballantyne a chance to demonstrate that he isn't really Edwardes, because, unlike Edwardes, he doesn't know how guilt complexes work.
Mr. Garmes tries to kill Fleurot (can't blame him there) and then tries to kill himself. He doesn't succeed… and then he largely disappears from the film. Is his guilt ever cured? You never find out. He's not the main character, and Spellbound doesn't care about him.
It doesn't even feel guilty for not caring. Harsh.