Normal Frustration Reaction Or Something Deeper

There are a lot of people who don't display traits or behaviors that seem dysfunctional, abusive, or Narcissistic until they're in a situation that "tests" their ability to empathize, care for others, or be responsible for someone or something. Many of us who have anxiety issues are aware of a similar issue; no anxiety at all, calm confidence and even-keeled focus until we find ourselves suddenly dealing with a certain situation or circumstance.
For most of us, fortunately, we can heal our 'dysfunctions' or 'issues' when we find out that we have them, and often a situation that we find difficult to deal with is just a matter of our needing more experience or understanding.
But for some people, the behaviors and 'issues' that seem to suddenly appear when they're dealing with a specific situation is not simply an emotional or anxious reaction to difficulty that will get better when they get a handle on themselves or on the situation. Rage and aggression toward others, cruelty, deliberate sabotage, deliberate slander or libel, threatening another with bodily harm, removal of another person's shelter or resources, restriction of another adult's freedom, physically restraining or controlling another adult, aggression toward a child, elder, or ill, injured, or 'handicapped' person, or deliberate abandonment are some of the behaviors that are not simply 'emotional reactions' to difficulty or frustration. The reasons behind these behaviors vary, but they aren't just 'frustration'. They're signals that there is something deeper going on with the person.
We should not, however, jump to conclusions about what the person's "issues" actually are. What looks like PTSD at first could turn out to be brain damage, or what we think is Narcissism could turn out to be PTSD, etc., etc.  What we can do, however, is make sure that we are safe, and that others around the person are safe, especially children, elderly people, and anyone else who might not be able to defend themselves against the person's behaviors.
When we're sure we're safe, then we can contact professional physicians, psychologists, or psychiatrists about the person's behaviors, (preferably a person whom we already know and trust to be objective, professional, helpful and competent.)