Contrary to popular belief, stalkers are not a problem relegated only to celebrities. Ordinary people can also end up having to deal with someone following their every move and observing their daily activities. The fact is, it isn't just fame and fortune that makes someone so obsessed with another person as to follow them around and literally center their perception of reality around another human being. Especially one that likely doesn't even acknowledge or is aware of their existence. Stalkers can be interpreted as having mental health problems, though they are similar to sociopaths, in the sense that there is no single, simple explanation that covers all forms of stalker behavior.
The mental health aspects of stalker behavior are rather interesting to note, particularly with regards to the psychoanalysis of it all. Stalker mentalities tend to follow a general pattern of development, as noted by several expert observers. After first contact with the object of obsession, the stalker tends to develop a sort of infatuation with the subject. This, in itself, is not entirely unusual, with the average human being developing such feelings throughout their lives. The second step, which involves overcoming natural anxiety and making contact with the subject, is also reasonably normal behavior. However, in the event that the person is rejected, the reaction can sometimes be cited as the critical point.
The delusion that forms afterwards is the core of the stalker's behavior. His supposed feelings for the subject are projected towards that person, making it seem as if the feeling are reciprocated. However, the delusion itself is, by nature, not entirely consistent with itself. The anger over the rejection is still present and serves as the catalyst for the more obsessive aspects of stalker behavior, which may eventually lead to the self-destruction of the stalker and the destruction of the object of obsession.
The narcissistic nature of the fantasy, of course, demands perfect consistency. This is speculated to be the driving force behind stalkers taking steps to make sure “competition” avoids the subjects of their obsession. The fantasy is damaged when the stalker's perception of the obsession proves to be inconsistent with the reality of it, such that measures are taken to force the consistency to exist. This explains why some stalkers are adept at developing rational explanations for behaviors in their targets that do not coincide with their perception. However, this rationalizing can only go so far. When pushed to a breaking point, usually by some perceived betrayal of his feelings, the stalker may answer with violence.
Statistically speaking, stalkers do not usually cause bodily harm. In fact, while most of them are adept at using threats of harm and violence, many do not actually carry out such threats. In the cases involving psychopaths and sociopaths, wherein the mental disorders are interlinked with the stalker's behavior, violence is more likely to occur. For the most part though, the real damage stalkers do to their victims lies in the non-physical forms. Emotional abuse and psychological trauma are hallmarks of being subjected to stalking, particularly if the problem has been persistent for an extended period.