People change personalities to please different types of people.
A person can have multiple personalities. It is the person who has the disorder and not the personalities who have the disorder.
No! A vivacious personality is a lively, vibrant personality. A vicious personality is a cruel, malevolent personality.
Personality development
For all intents and purposes, I will say that the personality is how one acts. How one acts, talks, thinks, what they believe, what they consider most important in their lives, is all a part of one's...