A character of mine gains certain abilities after a creature fuses with em as he dies. However, I don’t know of any supernatural creature that would do this or something similar which might explain the phenomenon in the story. I could make one up, but having it based on something would help me make decisions about the world around it and keep things related.
The story itself centers around disillusionment, and the abilities the character obtains is supposed to reflect a drastic psychological shift in the character.
Any creature or being that might bind to a person, react to/be affected by their psyche, and give them supernatural abilities is what I’m looking for.
For more context: The story itself explores disillusionment. The character is outcasted royalty (survived an insurrection against the royal family) whom is betrayed by es would-be lover and left to die in a mysterious wood.
This event, compounding on past events over the character’s lifetime, inspires a passion for vengeance in the character and a drastic psychological shift.
This shift results in the character’s yang and yin traits inverting, (essentially replacing each-other), reflected in how the supernatural abilities gained are based in fire, light, and rigid kinetic energy.
Additionally, the character’s body is warped somewhat thematically, as es hands— which used to tend gardens and write— rot away, and the only way for the character to sustain itself is through extracellular digestion (like fungi); e’s weakened substantially by darkness, cold and water (unless it's boiling hot); and es eyes glow among other aesthetic changes (sharp teeth, floaty hair, constant buzzing noise)