They Frequently Lie
A psychopath will lie about almost everything they do, regardless if they actually have a reason to do so. This can include where they have been, who they were with, why they were there, and the like. They don’t care how their lies will affect another person, and will never own up to a lie. Instead, they will twist your words and make you think you were the one in the wrong.
Psychopaths will even lie to get you into a relationship with them by telling you they like and want the same things as you. In reality, they don't like or want the same things as you at all. The only thing on their mind is the need to have control over you. A psychopath will lie in order to get what they want, and can even see it as a fun way to manipulate other people.