Who to trust?

Well you all have this kind of friend who always tells you they got your back, but everytime you're in a fight or an argument he is gone as the wind?. People i just met back me up but a close friend shut me down when i need them.

I always think what would i do in this kind of situations? often i just freeze and wake up when everything is over so i'm not perfect either. But i dont go around and tell everyone how i got their backs in every fight. Often they don't consider me as a fighter. Becouse i'm not a fighter i'm the guy that always just get beaten up badly and then often laught about it later.

What i'm trying to say is this, if you have a friend who always are acting tought dont count with them in a fight often it's a suprise who is really holding your back when you need it!