1. Hide their real identity.
2. Instigate/provoke certain behavior in other person.
3. Try to confuse the other person.
4. Upon getting a reaction out of that other person due to that confusion created, call that person a psychopath.
5. Gossip about it to other people or make open accusations about the reactions.
If you fight well with the psychopath, you will be considered a psychopath; and if you get emotional, you will be sympathised with considering you weak mentally; and if you ignore, you will be instigated/provoked again after an interval of time and maybe in a different way.
Stay alert. If you won’t keep these things in your mind, it will be very easy for a psychopath or narcissist to manipulate you and/or people known to you. It’s very easy to be provoked but consider that the one who has hidden his identity is already a Coward, and who has gossipped or gathered others to discuss you or your reactions is Mentally Weak.