Zombies are the bodies of people who’s souls were not properly released upon their death. The reason for a soul becoming trapped in a body is currently unknown, though there are many theories, ranging from “not properly put to rest” to “died on a night with no moon.”
Because the body still contains a soul there is a chance that it will reanimate; however, it is still dead, and it will begin decay and rot like any other corpse. This can lead to terrifying experiences for those who discover a zombie, as they are often met with insect-filled rotting flesh that is practically melting off the body.
When a soul becomes trapped in the body of the dead for too long it expires, and becomes a more physical component of the body instead of an ethereal one. As a trapped soul ages it slowly begins to turn into a black liquid which oozes from the zombie’s rotting body like blood from an open wound. At first this ooze is watery and pale, as the soul is still trying to hold itself together. However, as time goes on the soul will darken and thicken, and the amount produced will increase.
During the early-stages of zombiesm the souls may still be able to communicate, at least somewhat, with the living, and there is a chance that they can be freed from their body to move on to the afterlife. But as the soul ages the zombie will lose the last of its consciousness and become unmanageable and aggressive.
Zombies are often compared to soulless undead; and though behaviour in the early stages of zombiesm may mimic some symptoms of a soulless, the later stages prove to be very different. This is because the two undead are opposites, with soulless lacking a soul and zombies retaining their soul.
Though it is unclear how the souls become trapped there are many known ways to release a soul from an early-stage zombie. Some common methods include saltwater baths, soulstone arrowheads, and burning the body of the zombie.
If a zombie is left to long, there is a chance its flesh will rot away entirely and it will become a skeleton.