Personality disorders that relate to odd or eccentric behavior are paranoid personality disorder, schizoid personality disorder, and schizotypal personality disorder.
If someone has a paranoid disorder, they usually show it by being
alone and out of the way most of the time, in fear of close relationships.
They fear that someone is always out to get them and they have
motive to hurt them. They tend to search for hidden meaning in
almost everything because they fear once again, that someone is
out to get them. They usually don't trust many people and when
something goes wrong in their life they tend to blame it on someone
else. They also have a tendency to hold long grudges against people.
If someone has a schizoid disorder, they don't seem to be affected
by anything. They show no emotions to anyone and criticism and
praise doesn't raise them up in any way. They try to avoid relationships
and tend to choose jobs with low personal interaction. Others perceive
them to be humorless, emotionless, and are classified as loners.
If someone has a schizotypal disorder it could be a sign of mild
schizophrenia. This is where the person has an odd way of thinking
and perceiving things. Their speech is usually over eccentric and
hard to follow. Usually, people with a schizotypal disorder will
anxious or nervous in a social situation. They seem to have strange
beliefs on magic or paranormal phenomena. The person will also
suffer from suspiciousness and paranoia.