Ghosts are the most pure form of undead. They are the soul of a person that has not moved on and who remains on the planet despite having moved into the incorporeal realm.
Though they have shifted to another realm many ghosts are able to appear to people, especially people with a strong connection to soul magic, dream magic, telepathy, or those with prophetic powers. Their appearance is similar to what they were in life but also may reflect how they saw themselves. A strong, focused spirit may appear as their ideal selves; while a spirit that is less in control will look closer to how they were in death— Often, when a ghost becomes upset their visual form will shift to match how they appeared upon their death. This can give some disturbing visuals as the spirit may suddenly age or have wounds ripped into their bodies.
Ghosts are rarely seen when they do not want to be seen, even by people with strong spirit-seeing abilities. Some ghosts may also appear to people who otherwise would not be able to see them, though this takes a particularly strong spirit. These spirits are usually so strong that they are able to interact with the physical world as poltergeists.
This poltergeist ability is also shared by some weaker spirits who may still have a connection to the physical world. These spirits are recognised by the sticky, black trail of soul that they leave behind on objects they touch or in places they have been seen.
Though some spirits may appear to the living, there is one that may prevent even the strongest spirit from returning to a loved one— Grief. Grief acts as a blockade for spirits and the people who miss them, and if either grieves for the other it becomes more difficult to create contact. Not much is known about why this effect comes from grief, and some people argue that it doesn’t exist (though there is more evidence for it than against it, including the testimony of Immortal Queen Distro).
It is believed that ghosts are not always formed by the death of a person. They are formed by the expulsion of a soul from a body, and there are theories on the creation and destruction of souls, and whether severe and permanent memory loss is a form of spiritual death that creates or destroys a spirit. There have been claims from those with memory trauma who say they’ve seen the ghosts of their past selves, but no definitive proof has ever been documented.
This theory is most commonly believed in the Rendi, where the spirits of past memories are referred to as the “lost siblings” of those who suffer amnesia. It is also known that several Mystic races, such as taurs and fauns, share similar beliefs.