The Report on Entites
An extract from New Encyclopedia of Magical Theory by Tom Willis.
Introduction: One of the most mysterious things found in our world are beings known as the entites. No one knows what an entite really looks like and they are commonly held to be a force of nature. Each entite represents one particular negative emotion and they manifest in places where such emotions are or were commonplace.
1. The Fear Entite
One of the most common entites to be found. Colloquially known as the Boggart among other designations, these entites are capable of transforming into a shape that represents the victims worst fear. A common way to deal with the entite is to force it into assuming a shape that the victim would find amusing by the use of spell invented by an unknown wizard c. 1710. After that, in order to exorcise the entite, the victim has to override the emotion of fear to one that the entite cannot feed on. Since the entite represents fear, they can be found in places where great fear was shown. Examples of such places can be manors belonging to old wizarding families and even old Wizarding Schools have documented encounters.
The Rage Entite
The rage entites, while rarer than fear entites, naturally represents rage and affects its victims by invading his/her mind and forcing the victim to relive his/her most painful memories in order to incite endless rage. Note that these entites should not be confused with Dementors. These entites can be found in places where great pain was shown. Thus they can be potentially be found anywhere and it is recommended to always stay on your guard. There are no known methods to fight these entites but the one who has a strong mind can resist it's effects.
The Lust Entite
These entites manifest in places where great and one sided sexual attraction was shown and like the rage entites, invades their victims mind and make them lustful to their surroundings. All that the victim can think about it is sex and nothing else. Since these are known to manifest in places where great and one sided sexual attraction has occurred, these are sometimes found in brothels, especially old and disused ones. There have also been one documented encounter in the Ravenclaw common room at Hogwarts. What happened in there in order to attract a lust entite is anybody's guess. In any case, one should be careful if one suddenly starts acting strange.