A two faced person could be a friend or a family member.
Anyone who talks to you behind someone else’s back and befriends that person at the same time will do the same thing to you behind your back.
They thrive on creating friction between people. Every day they have to think of something bad to talk about to someone else because this is what gets their adrenaline pumping.
Two faced people can not be trusted because all the do is make up lies at the expense of others just to get attention. Your life has to be pretty boring to want to hurt others so badly you would do this.
No one needs people like this in their life the drama is not worth it.