The thing is, Nocton was a child. His forms of teaching were from a twisted mother and siblings that constantly tried to kill him and a negligent and clueless father that, from what I can see, was barely in Nocton's life. Nocton has to constantly be on guard, even in his own home. He could not show favour to Valrose because that was his one weakness and the only person that he could trust. If anything it's his one form of a stable relationship.
Honestly, I can tell why he's fucked up and lacks communication skills. His whole life is centred around not speaking about his issues or problems because he would get hurt because of it. To those who say "Its been 10 years its too late to reform.", I would say that actually trying to reform is the best course of action. Although he can't do it fully because if he lets go of his hypnosis his family will just go back to normal and keep trying to kill him. Hell, even the staff will try to fucking kill him as we've seen. He can't trust anyone except Valrose but he can't tell her for fear of her leaving him and for the stigma of black mages surrounding him which is most apparent in Alice and Aaron's actions which is to either be afraid of him or be hostile towards him (although they have a good reason for it) The entire reason for his hypnosis was keeping himself safe, which I am sure all of you can say is for a TEN-year-old child to do (I mean how fucked up is it that his own mother and brothers are trying to fucking kill him. He was never taught how to use his powers or how to use them ethically because NO FUCKING ADULT WOULD TEACH HIM). He had to do this constantly up until his adult life.
Y'all complain about him using hypnosis on and "destroying" the girl's mind when in this chapter he states that hypnosis is actually the safest form of black magic if it isn't used often. He destroyed his mother's mind In order for her to be neutralized. He didn't do that level of destruction to anyone else because of Valrose. (Which is a complete mess of Noctons end of trying to figure out whether he brainwashed her or whether he didn't and it's pretty much fucking him up because he wants a friend but he also isn't quite sure how to have a friend that he didn't hypnotise into liking him so they wouldn't kill him from his mother's influence).