“Luminous beings are we, not this crude matter.”
— Jedi Master Yoda, from The Empire Strikes Back
Souls permeate fantasy. You find them everywhere. In books like the Vlad Taltos series; in movies like Crimson Peak; in television shows like Buffy the Vampire Slayer; in video games like Jade Empire; in anime like Soul Eater; and manga like Fullmetal Alchemist. Even if souls are not the focus of the story, it is almost always assumed that souls exist. In some universes, all living things have souls, while in others only sentient races have them. In a few, only humanity is granted this unique ability to transcend oblivion.
To clarify, the idea of a “soul” is that some ethereal essence is separate from the body and contains all of the characteristics that make an individual unique. Souls leave the body at death, or can be forcibly removed by various spells or magical artifacts. Upon death, the soul becomes vulnerable, little more than a tasty, glowing morsel for hungry demons or power-ups for magic weapons. Depending on the story, sometimes souls can be returned to their rightful bodies, be placed in other objects or bodies on a temporary or permanent basis, or they are released to go to the afterlife. Because, if beings have souls, then something has to happen to them after physical death. They can go to some kind of afterlife, transcend to a new plane of existence, or be reincarnated.
The presentation of souls is also highly varied. In some stories, they retain their sense of self and can make their own decisions, like Obi-Wan Kenobi. Others may degrade, either immediately or over time, trapped in one place or reliving a snippet of their former lives, like the ghosts and spirits in many horror films. In many Japanese anime and manga, souls are just the spark of life that animates a body and remain indistinguishable from one another. Such souls seem to have no agency of their own and must be protected. Some beings actually feed on souls, a highly unnerving but rarely discussed topic. If souls are immortal, can they really be destroyed? Can souls feel pain the way a physical body does (only worse because death will not release you)?
The idea of this eternal(ish), separate entity underlays almost the entire fantasy genre. Science fiction even touches on it sometimes, although usually in a philosophical sense rather than a literal one. But fantasy, more often than not, simply accepts the notion of souls, often accompanied by gods and an afterlife. I don’t think I’ve ever seen a work of fantasy that challenges the idea of a soul directly. It makes sense that characters in various worlds would possibly believe in the existence of souls, depending on their culture, religion, and philosophy. But whenever there is a culture or character that doesn’t believe in souls or an afterlife, they tend to be presented in a negative light. The implication that believing in souls is correct remains, even if it isn’t the story’s focal point or driving force.
This can really impact the choices characters make and their view of the world. Does it make them more concerned about how they act and treat others, because their actions could have eternal ramifications? Or do they have less concern because it’s just an eye-blink in existence and doesn’t matter in the grand scheme of things anyway? How does this affect their reactions to the daily grind of life as well as to unusual circumstances? Is there any concrete proof that there are souls in that world? And if they don’t believe there is such a thing as a soul and there is no evidence of life after death, how does that change things for them? Would it be liberating or terrifying? Would it make them act better or worse towards others? How would the existence of souls (or lack thereof) affect races that have different lifespans from humans?
These are all questions to keep in mind while world-building. Addressing them could create an interesting dynamic in an otherwise traditional fantasy.