Recently I've slowly been trying to sketch the other characters in the redesign setting/project, and demons certainly are some of the tougher subjects to capture in a way that makes me happy. Ah well. At least I get to go hogwild with Damien's design.

Demons are a specific type of "living spell" and the most common stable lineage of living spell, natural or unnatural. Living spells are a type of magic which replicates and reproduces the effect of a living organism. This can occur either attached to an object in which the spellwork is written upon, or it can occur without an object, with the pool of magic itself having taken on the structure and qualities of a spell in action. Much debate has been had over living spells and their origins, which are hard to trace and impossible to fossilize, as well as how to produce living spells intentionally, which is a complex process that is hard to replicate.

Demons, being stable and not at risk of using up their pool of internal magic, as well as having notably large pools of internal magic, tend to accumulate magic and grow in magical potential over time. This is not actually a good thing for the demon — surpassing the natural bounds through which their spell is designed for even slightly risks turning it unstable and degrading it over time, if not completely unraveling it and killing the demon in what is usually regarded as a "fiery explosion". Thus, demons shed high amounts of workable magic, and regularly seek ways in which to rid themselves of excess magic, making them an easy and mutually beneficial source for other parties.

Demons also have multiple lineages, which define slight differences in their internal spellwork, mostly concerning the rate at which they accumulate magic. Some accumulate it slower and are more stable, while others accumulate it faster and are less stable. Damien belongs to the latter, having a high amount of magic that he must burn regularly. Since the easiest way for magic to manifest is through sparks and fire, this burning off is usually quite literal.

The shape of a demon, like magic, is a tangle of accumulated environmental influences, and shifts regularly, at their whim or unconsciously. Typically they take great pride in this shifting appearance and enjoy working it to their satisfaction, as how they look has little to no effect on how they actually navigate the world. All of their senses are tied up in the internal spellwork, and cannot be manipulated by physical objects without special exceptions, so everything that is seen, eyes, limbs, organs, bones, and all, are all merely illusion, and have no correlation to the internals of the demon.