Are you taken advantage of easily? Do you find yourself not being able to tell who is a friend in your life or who is a “Foe”?
The answer is always by how they treat you and respect your boundaries. Look at someone actions vs words.
Someone who has empathy and is being genuine will always let you know their boundaries and expectations, will always respect your boundaries and will always act with integrity and display consistent in behavior (actions match their words) . As soon as some displays otherwise- trust your gut and walk away.
You owe no one an explanation, set firm boundaries and exit the interaction. My experience with social predators (the very charming, grandiose ones) is that when you establish boundaries they will get very angry with you.
That is how I figure out if someone is being a friend or foe? Also I set up boundaries to ensure manipulation is not an option. Always for self protection set up good boundaries as well.
Do not become a target, learn how to develop a healthy self-esteem, boundaries and how to not live a life of ego and all of the sudden you will see you are not longer a target.