Responses
I think he didn't go insane so quickly. I mean in the 5th chapter kinda showed that someone killed the students who were bullying Katou on the news report. The students were still 17, so that meant that someone killed them when they were still in school. And when Oda said that Katou was special regardless of having powers, I think that just means he was always crazy.
Just that the whole hearing thoughts thing made him more insane because it "confirmed" that Katou was his or smt ╮(￣▽￣)╭
I don’t really get why the blond guy went insane so fast ╮(￣▽￣)╭
Also I really wanted an explanation for why the black haired one lost his abilities and the other got to keep him. Also wasn‘t the only reason he liked him because he couldn‘t hear his thoughts?