Spiritual Influence

Ghosts, poltergeists, and demons, Spiritual Entities capable of interacting with the physical world, may influence incarnated spirits, or physical beings, in several ways. Incarnated spirits must give implicit or explicit permission to be subjects for attachment, oppression, or possession.

Presence

Ghosts, poltergeists, and demons may make their presence known by moving objects, manipulating devices, or manifesting sounds or their voice in the environment provided they have the energy to do so and haven't been commanded to silence or stillness by an incarnated spirit.

Attachment

Ghosts may attach themselves to incarnated spirits in order to leave locations significant to them. They must remain within the incarnated spirit's energy field, which varies in radius from spirit to spirit, in order to maintain this attachment. Once the attachment is severed or the incarnated spirit revokes their permission, ghosts return to the nearest significant location to them.

Poltergeists are attached to their host and can't attach themselves to any other incarnated spirit.

Demons may travel where they please but require permission to enter an incarnated spirit's domain. Demons "attached" to an incarnated spirit have attained this permission.

Oppression

Incarnated spirits under oppression are affected by another entity's emotions, thoughts, or will. Those not host to a poltergeist in their presence may still sense the poltergeist's emotions. Incarnated spirits may feel a ghost's emotions or act upon their desires. Demons may influence incarnated spirits to perform acts or think negative emotions or memories. Incarnated spirits may even become physically ill under the oppression of another spirit.

Ghosts, poltergeists, and demons must expend some level of energy to conjure subconscious thoughts in the incarnated spirit's mind or manipulate their body. The more sensitive the incarnated spirit is to other spiritual beings, the less energy that must be expended. Sensitive incarnated spirits may be aware of their oppressor's influence, hearing their voice or sensing their presence, but conscious awareness isn't required for oppression to occur.

Possession

In the most extreme cases of oppression, ghosts and demons take direct control of the subject's body to speak or otherwise exert their will. Poltergeists don't have this ability.