While the exact specifications of this gene are never truly explained, it is generally assumed that the gene allows for a person to have a parasite/host type relationship with a malignant spirit referred to as a "devil" as well as having it (the gene) control the transformations of one to the other. The exact requirements for these transformations are never fully revealed. The spirits can possess the person at any given time during the person's lifespan, even while still in their mother's womb or (apparently) just after death.