This key has the ability to split one's soul into two separate beings: one evil, the "dark side", and the other the good one. It appears that while splitting the soul, it also creates a body manifestation for each one, which will reattach by using the Inner Key again. Although separated, their physical bodies are still connected by a magical repercussion effect, and so if one gets hurt, the other will do as well. The Inner Key can also reverse the soul splitting spell by simply being hold against one of the halves' chest.