The man just learned that his wife has been scheming and poisoning his daughter without his knowledge for years. If he thinks his son might have inherited her way of thinking, then it’s not enough for me to brush it of as “he probably heard that from his mother.” The fact is that the FL’s brother might be instinctively trying to preserve his seat as future headmaster and it does take a subtle amount of cunning smarts for that.
If he becomes headmaster, then there shouldn’t be a question as to whether his sister could take the position away from him. In some clans, even if the woman gets married, the man will move in into their clans because the woman’s clan is of higher status (like it’s the case with Dang and Eon). However if that’s the case in that situation and his sister stays within the Dang territory, it might call into question his authority, like when different lords or people in power choose sides despite there being a clear leader.
how abt we turned back time when the brother still a baby and teach him common sense and martial arts? it's really killing me when he don't know a shit and overestimate himself.