This an an excerpt from this site: Long read, but very, very good information...
What is a Psychopath?
If you try to deal with psychopaths in an ethical manner, you will be in for a shock. Dr. William Higgins claims that you "can't negotiate or bargain with psychopaths."
Psychopaths will not only deny the past and trivialize it, but will avoid answering your questions directly, and even if they seem to answer them -- you can be sure that it's not the answer you were looking for. It has been said that even when they do give you a straight answer, the real issue will never be addressed by them, although they may even claim to be honourable when it suits them. But don't be fooled, for this is where the psychopath wants his victim -- he wants to shame you while at the same time fitting you into his plans; this is because "psychopaths show a stunning lack of concern for the devastating effects their actions have on others. Often they are completely forthright about the matter, calmly stating that they no have no sense of guilt, are not sorry for the pain and destruction they have caused, and that there is no reason for them to be concerned." [Hare, 41].
On the other hand, "psychopaths sometimes verbalize remorse but then contradict themselves in words or actions." [Hare, 41]. Psychopaths may apologize or show remorse only to get away with something, but in the end you will be stabbed in the back and realize how very shallow their words were.
The psychopath appears not to be able to remember what they had said or committed to for very long. They seem to always be living in the present. That is why they are usually guilty of being big "promise- makers" who cannot live up to their word. Once again, it will be the victim who must deal with the aftermath of all the psychopath's twists and turns, and when he gets you angry enough, you will be discredited as "defective" by him, and the psychopath will often make himself out to be the real victim. As John Wayne Gacy once said, "I was the victim, I was cheated out of my childhood."
What often happens in the aftermath, as Field has stated, is that the victim may repress his or her anger for a quite a while, but then, often many months later, a sudden realization of the truth may come over the individual, and the victim will finally realize that all along he/she has been bullied by the psychopath. This is when the victim suddenly becomes very angry and is motivated to have some sort of justice. But when trying to obtain justice with a psychopath, be aware that you will be the one to pay if you don't take a firm stand; the experience will have you more confused and bewildered, and you may even feel tempted to fight fire with fire.
In some cases, our society allows psychopathy because we do not really fight back against cheating and lying behaviours (one good example: Bill Clinton). They are also good at tricking their own psychiatrists. For instance, two individuals I (Wendy Koenigsmann) knew bragged that they liked to play mind-games with psychiatrists.
