Many Jewish commentators such as Rambam (Moreh Nevuchim 3:10 explains that evil doesn't have a reality of its own, but is merely a privation of good) thought that evil was merely the absence of good much like they stated that darkness is an absence of light.
Based on this interpretation, how are we supposed to understand demons and evil spirits? Are they merely a regular spirit that uses their volition to act evil and as such, have a yetzer hara of their own or are they something that has an intrinsic property of evil that were perhaps created by humans after the fall? Do they have an ontological status of something evil?
Assume that unlike Rambam, we don't interpret that shedim are metaphorical, but are actually real as briefly explained here.