Monokuma, a character from Danganronpa the Animation (picture source: http://danganronpa.wikia.com)
Bismillahirrahmaanirrahiim…
When talking about alter ego, we often think about its negative aspects. I do not know much about psychology, but, in my opinion, alter ego is a mechanism of a person to fulfill different expectations from his/her social environment. For example, B is a student. He is known as a polite and kind person in his neighborhood, but often bullies his juniors at school because of peer pressure. His peers will assume that B’s alter ego is how B interacts in his neighborhood. Yet, his neighbors will think the opposite, since they already have a mindset that B is polite and kind.