They appear to have a split personality
They keep switching from one extreme to another. You never find them to be consistent in anything. They’d go from loving you to hating you in no time, and then back to loving you again.
They don’t take responsibility for anything
According to them, none of their problems are caused by them. They always pin the blame on someone else. Everything that goes on in their life is because of someone else. They don’t own up to anything, not even their own mistakes.
Their stories never add up
They mount up lie after lie, after lie in every story they tell. When you point out the gaps in their tales, they never come up with a satisfactory answer. You’ve no chance of getting the truth out of them, ever. They’re pathological liars.