Gemini is a strain of Animus Parasite That prefers to subsist of pairs of souls. As finding free floating souls is hard to do as it is, Gemini tends to linger around pairs of people that are close to each other. Typically these are twins, though exceptions are rare. Gemini impales its spikes into a pair of souls and produces a spiritual webbing that serves to keep them in place.

Should one of the pair die, and Gemini parasitizes both of their souls, it stays within the body of the living host, with both souls surviving inside. over a course of time, the host will begin exhibiting mental changes until they start to act like the other person whose soul is inside of them. In advanced states, they physically become the other person, morphing their physiology entirely as they swap back and forth.

by  Sarbat