Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
First, set boundaries. Don't let them cross into your personal space or control your life. For example, if they try to interfere with your career choice, firmly say no. Second, avoid getting into their emotional games. Don't respond to their attempts to manipulate you emotionally. And third, seek support from outside the family, like friends or a therapist.
Yes, there are some so - called 'psychopath success stories'. Some people with psychopathic traits may succeed in certain fields like business. They can be extremely focused on their goals, unafraid of taking risks, and very good at manipulating situations to their advantage. However, it's important to note that their lack of empathy can also cause harm to others in the process.