Pentral

A pentral occurs when a person's entire soul (as opposed to a fragmented soul like with Horcruxes) is extracted from their body and contained in an object. The extraction of the soul typically utilises dark magic, leaving its victim in a state of despair and lack of consciousness. This state is not dissimilar to that of someone who has experienced a Dementor's Kiss. More often than not the victim is killed. Pentrals may be used as a source of magical power. However, this is likely to take a physical toll on its user(s).

From A swarm of souls upon thee!:

"If trapped in an object or a person for a long time, a pentral may become twisted and bitter. If released without the use of a binding ritual, they may wreak havoc like poltergeists, or try to possess the living. If a living person is forcibly possessed, both host and pentral may suffer loss of self as their identities merge. In some cases, the host may not survive or the pentral may dissipate.

Continually hosting a pentral will take a toll on the host's body and mind. To offset the effects of storing two sentient souls in one body, a host may resort to drinking unicorn blood."