Is this guy a psychopath? He was a "quiet one"?

[Thomas]

I think it's difficult to judge someone by how they act when they get into a fight. People get upset for different reasons. Every person is different. There are different conditions that can look similar - fetal alcohol syndrome, psychosis, PTSD or someone could just have an explosive temper. The only reason to put labels on people is to know how to bill the insurance company.

About half of a percent of the population could be considered sociopaths, that's about one out of every 200 people, so it is fairly common. Less than one percent but still enough to be concerned about. People like that are best stayed after from. Just don't have any contact with them. The only time they feel alive is when they set the drapes on fire. They enjoy hurting other people.

From your description of Trevor and Justin getting into a fight, that doesn't really provide much useful information. That is just behavior, not the underlying reasons or motivations. All behavior is a form of communication.