Life forms are patterns that promote their own existence (or the existence of similar creatures, such as offspring) sometimes to a self destructive extent (as in the case of exponentially dividing bacteria).
It may be that such patterns exist within the nervous systems of sentient organics and/or computers (sort of a parallel to computer viruses). Although these patterns may be quite complex there is no necessity that they be sentient per se. In some cases these patterns are the by-products of existing biont or ai mental processes, perhaps they were somehow transferred between individuals or created on purpose. Some might incorporate well into an individual's existing mental processes (becoming a useful part of the mental biome) while others might take the form of destructive tendencies. Demons could include semi-mythological antagonists, obsessive compulsive disorders, phobias, depressions, computer viruses (and organic tailored variants designed to infect those who interface with machines).