Classification: incorporeal aberrants ("demons") who can hijack human bodies (and do so to sow chaos and violence).
Colloquial name: Hellbourne, possessed.
Origin: after their fall, the former angels created a dystopian, hierarchical society. The majority of its members are sent "up" to cause strife in order to test the inhabitants of different worlds, as part of the Demon Accords.
Description: as most demons cannot manifest a body of their own in the material universe, they appear as amorphous beings made of oily black smoke. Their hosts do not show any outward signs of corruption, although their bodies can be altered once the demon becomes powerful or determined enough.
Behaviour: most demons are anarchistic, mass-murdering sadists, who display a disdain towards Earth's society while simultaneously following the customs of theirs (but this is a lie, as demons only care about themselves, and are always looking to drag down those above them). While some older, higher-ranked ones can plan and keep a cool head, most of the ones sent to Earth to possess people can only lay low for so long before their predatory urges kick in.
Most Hellbourne whose personality isn't immediately overwritten by their demon are unaware they are possessed, even though the creature's presence is likely to make them antisocial and violent without it exerting any effort. During the stage preceding complete possession, the host might display exaggerated versions of their worst flaws.
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Threat level: local (?). Hellbourne can push their host's bodies to superhuman extremes even without enhancing them, allowing them to perform feats that would cripple or kill humans and keep the flesh moving through sheer will. Powerful Hellbourne can either assume their true forms or modify their stolen bodies to the point they resemble those, allowing them to match angels in combat. Demons are imperceivable while incorporeal, to both human technology and the superhuman senses of most aberrants without "spiritual" perception. They can extend this to their host bodies at will. It is currently unknown if low-ranked demons can perform feats similar to angels exerting their will upon the world.
Neutralization: it has been observed that the presence of holy objects (belonging to any religion) can be harmful to Hellbourne, as long as those bearing them truly believe in what said objects symbolise (this is not foolproof; see the case of the hellish preacher taken down by Chris Gordon and his associates, who had a demonically-tainted Bible). As such, the fabrication of such objects would be useless, as we Zhayvin pray to no one and nothing, and never had. Thankfully, we possess equipment that can interact with aberrants in all states of being, and these demons are not beyond the combat ability of even an unarmed reptilian with the means to affect them.