Read a spoiler that the father of the Empress and Siege’s brother are the villains. Siege being so perfect and talented, his elder brother was insecure and thought that he may not inherit the title. Idk the details but I think since Kentryle was explicitly uninterested in inheriting the title maybe elder brother of Siege thought he could snatch the county if he eliminated Kentryle’s brother and his family.
Kentryle’s Uncle who is the Emperor’s father-in-law might have some benefit if his puppet becomes the Count instead of his nephews and might have helped that guy.