I just wanted to share a theory I have about the workings of the human psyche and the "entities" it can create. I have no idea if anyone else came up with this before but I think a few of you might find it interesting. First I will explain the definitions of a few things as I learned them.
1. Thoughtform: A manifestation of mental energy. Thoughtforms can be as powerful as the person that created them. It has been suggested that they can gain a consciousness of their own.
2. Shadows: I have learned of two different things that these can be. One is a manifestation of our own psychological issues. The other is a form of malevolent entity that feeds off of energy from you through the provocation of negative emotions.
3. Dual/split personality: The devision of separate aspects of personalities. This can manifest as a positive and negative side or a complex matrix of emotions and behaviors but in separate defined groups.
Theory time lol: When a person has two parts of their personality that are conflicting they will often separate them. These two separate personalities are then "split" or "dual". If these personalities conflict too much the subconscious mind can then make the less desirable one into a thoughtform. If potent enough this thoughtform can develope a conciousness of its own. In doing this it becomes an entity on its own. This entity is a form of "shadow" because it shadows the parts of our psyche that we repressed.
Sometimes this "shadow" decides to feed off of its maker. Once in a weakend state the person becomes vunerable to its shadow. If the shadow attempts to merge energy back with its maker it can cause a shock to their system. This can cause symptoms such as memory loss, extremely abnormal behaviors, moodyness, violent outbursts, fatigue, weakness, and possible psychosis. These are only a few of the symptoms that can be caused by a "posession". I feel that most people being "possessed" are actually merging with the thoughtform they created from their undesirable personality traits.
Say whatever you want about this. I just felt like ranting in a somewhat organized fashion after finishing my research. I hope this can teach you something. If not maybe you will get a laugh out of it xD