It seems when it comes to human conditioning there are two kinds of fear - 'fear of losing security' and the 'fear of having lost that security'. They say humans are 'social animals'. I suppose given our fear of losing security that would be true; people want to trust others - it's in our most basic interest to do so and might possibly be more a result of higher evolutionary intelligence than anything else.
Normally the 'fear of losing security' manifests itself in moral beliefs and codes about how to treat or behave around other people. This gives a person clear definitions or delineations of thought that allow them to make well-informed decisions that should aid them positively in the course of their life. But what happens when that security is threatened? Normally, one would expect to trust more in those things that are secure and reliable or perhaps if that isn't available even, then they will act out in various ways - as an attempt to haphazardly demand that security from others. If the latter isn't viewed legitimately, it will be deemed socially unacceptable and the person will have no choice but to deal with the 'fear of having lost that security'. In this stage, there is no healing or sanity, one must either perish or numb themselves to the paradoxical fear that binds them. The pariah must become an animal, become a beast. This is PTSD.
An example of this is PTSD in soldiers. In war, they see and do things, while having things done to them that habitually engage their 'fear of losing security'. The atrocities of war leave its questioning mark on the certainty of human trust that they once had. They can either find solace in the securities they do have (such as family, friends, etc), which the military expects them to do; or they can act out in various ways to correct the situation, something the military doesn't encourage with its chains of command and orders (if you happen to go to a psychiatrist, you're booted from service). If the soldier feels hopeless, that neither option is good, they go to 'fear of having lost that security'. Now they can commit suicide or lose their humanity, but it's really that simple - one or the other. This is the nature of PTSD - to conquer fear and become a beast.
And when there is no longer threat of fear, it's so easy to see it in other people. Other people's preoccupations with what they value become almost everything that they are. I suppose these are simply the essence of projections. Behind all subjective weakness, one finds types of fear.