In Vincent's eyes, Chris is gentle, versatile, and intelligent. But I can only remember him in memory forever, because he is dead.
In the eyes of others, Chris is cunning, cold-blooded, and extremely powerful. He is so mysophobic that even his lieutenants doubt whether he is human at all.
Only Vincent thought Chris was dead. But when Chris came back to him again, Vincent realized that the Chris in other people's eyes was different from the brother in his own impression.
"Although it's just my guess. But let's assume that your brother deliberately reshaped your personality in order to completely possess you and make you rely on him wholeheartedly. Then the amnesia you had before the age of twelve and the drastic changes in your personality can be explained. Maybe looking at you who used to be cheerful and popular, he prefers you who is now so lonely that he is the only one with friends and relatives."
There is no trick, the brain circuit is unique. The perverted brother appears.