Hermione was not amused. Not. At. All. They had defeated Lord Voldemort after years of struggle. Witnessed the end. She had thought, with relief and without an ounce of charity, that she never had to deal with that pretentious, presumptuous, melodramatic, homicidal maniac ever again. Apparently the castle had other ideas.
Hermione is forced to fight for her soul, and the unanticipated person attached to it.
Hermione was back at Hogwarts for her eighth year, haunted by memories of the battle and those that had fallen. She could not have been prepared for the greater evil that awaited her inside Hogwarts walls, and the unexpected allies she would make attempting to protect her friends.