Never lie to someone who trusts you, and never trust someone who lies to you.  Although I did not come up with the quote it is perhaps the best piece of advice, I can give to anyone.  It took me almost 20 years to finally learn that. It is just the way it is. 

These types of people are ruthless and self-interested.  And they may believe they are doing it to not hurt anyone, but that is another lie that they are just telling themselves.  The truth is that you just don’t know where you stand with this type of person. The foundation for any relation is based on truth.  If you can’t agree on what the truth is then there is no stability or common ground for growth.

What I can say is this: once you catch the first lie, others will follow.  Just because it is the first lie you catch doesn’t mean it was the first lie they have told you. Know what to expect from that person, more lies. And don’t make important decisions based on what that person is saying.  Instead look at their deeds instead of their words.

Do not make the error of believing that they can change.  They rarely do and if they do it will only be temporary.  This is just another method of avoiding reality and delaying the inevitable.  There is a Spanish proverb that translated states “as the twig is bent so grows the tree.”  It refers to people that develop certain habits or attitudes and their unlikeliness to change.  

When you meet one of these personalities, just take it for what it is worth.  They may appear to be happy and amazing individuals.  Just steer clear and know that this is a fork in the road, and this road is best not taken.