Demons of Agnesia

The natural state of an Agnesian summonable demon (not to be confused with natural demons, whose form is consistent throughout dimensions) is a floating semipermeable membrane, and can only be correctly observed in their natural habitat: the Abyss. A demon has no physical shape until it is summoned into Agnesia, and even then, they do not choose their form. A demon's natural form, sometimes referred to as their photoplasmatic form, exists to provide the bare necessities for physical presence required for socialization and work.
A demon's photoplasmatic form can vary in color depending on their purity in life, from white (being wholly pure) to purple (being wholly evil). Demons, however, are privy to accessorizing and find themselves adjusting their visible color in a matter similar to how mortals consider fashion. Most demons wear their alignment visibly, but many purple-white hybrids tend to instead go for exciting colors such as yellow or green. This membrane dissolves food, providing energy, and replenishing a demon's biological sediment.
All demons' photoplasmatic forms have biological sediment floating within themselves. In a matter of speaking, this sediment acts as a demon's face as it portrays emotion and vibrates when communicating. As a demon's photoplasmatic form does not have limbs, demons have adopted several "dances" of their sediment to represent actions in a similar way to how mortals might hug someone or pat their shoulder.
Despite common misconceptions, demons are very-well adjusted to emotion and reason, and there exists a form of society in the Abyss that mimics that of Agnesia.