Possession

Possession is the act of a spirit or soul inhabiting and controling the body of another being. Possession generally occurs with Demons, Shades, and (rarely) familiars; but there are instances of living beings possessing another through an "Act of God". Possession suppresses the will and soul of the afflicted individual. Weaker spirits are unable to do more than surpress the soul and are more likely for the victim to overcome them through force of will. While possesed by a weaker spirit, the victim will remember everything the spirit does with their body. A stronger spirit is capable of locking the soul in a dream like state of the spirit's own design, to either entice the soul to remain in the state or torture the soul into giving up. While locked in this state, the victim is not aware of what is being done with their body, the illusion becomes their reality.

Transmission & Vectors

Possession is transmitted by coming into contact with the spirit in question. This could be by stumbling upon the object or place the spirit dwells, possessing the spirit as a familiar, or divine intervention. A spirit who finds a host unsuitable can jump to other hosts if the conditions are right (similar or weaker strength in their primary element, emotionally vulnerable, etc.). Jumping hosts requires physical contact between the host and new victim and most times mental manipulations.

Causes

When a malicious spirit comes in contact with a vulnerable individual, the spirit latches on and forces itself into the victim's body. It uses it's own energy and the energy around it to force itself against the soul and displace it. Vulnerability comes from the strength of the soul, the soul's elemental attunements, emotional distress, low willpower, and willingness to be possessed. 
A familiar's possession is often the result of the partner being in mortal danger and almost always is a result of the partner's willingness to submit to the control.
Possession by living beings requires a connection to the host and willingness of the host to submit to the possession. A god will facilitate these instances. Chrona is the only god known to be able to facilitate this across time streams.

Symptoms

It can be difficult to tell if an individual is possesed or not. They may or may not act like themselves, depending on the spirit's attention to detail. More often than not, personality changes and inability to recall events are the best indicators of possession.
Demons in particular tend to corrupt the body they posses, leaving markings such as decay or elemental aspected warping (Tera aspected demons will begin to turn skin to barky substances, Earth aspected to stone, etc). The warping starts at the skin and escalates the longer the individual is possessed. Elementally incompatible individuals will begin to decay. They also sever any bond with the victims existing familiars and even cannibalize the familiars.

Treatment

The only treatment is expulsion of the possessing spirit. While there is little danger in a familiar or living soul possessing an individual, Demons corrupt the body and Shades will eventually expel the soul.

Prognosis

Removal of malicious spirits early enough usually leads to a full recovery. The longer a shade or demon is in possession of a body, the more damage it does to the body and/or soul.

Sequela

Prolonged demonic possession while incompatible will lead to the canibalization of the soul and decay of the body. The demon will do it's best to hold the body together as long as possible, creating a sort of golem out of it and holding it together with it's own energies and random debris found around it. The golem serves as a mindless minion to do the demon's bidding. Compatible souls will find themselves cannibalized with the demon, cannibalizing the demon, or merging the two into one. In the case of the former, the body's corruption will halt, but not recover. In the case of flawless merging, the body will ascend to an amalgamation of the two, reaching an irreversable corrupted state.

Origin

Magical

Rarity

Rare