Demons
Also called Fallen Angels or shedim, Demons were corrupted extradimensional entities that were led into rebellion by the Ultimate Evil.

Demons were similar in appearance to angels. They were both amazing and terrifying. Demons on Legere took the form of androgynous, athletic humanoids with beautiful faces and varied pastel-coloured skin. Unlike Angels, a Demon's eyes were absent of The Creator's divine light, instead glowing with a fearsome magenta essence.
Demons differentiated themselves from the Angels by their uniforms. They would hide their faces behind fear-inducing demonium masks, wrap themselves in black garb, and don silvery demonium armour. They also dyed their wings black with ashes.
Slaying a Demon #
While Demons were immortal in spirit, they, like the Angels, were vulnerable to a (temporary) physical death.
The hundreds of Demons slain across the multiverse and in the Demon Wars on Legere would need a time period of a Legerian millennia to reincarnate. While this time seemed like an eternity away for mortals, this was but the twinkle of an eye for the supernatural hosts.
The Rebellion #
In an age long past, the Demons rebelled against The Creator, seeing the ties to their King as a limiting factor on what they could achieve on their own.
The archangel Samael led this revolt by creating the power of Evil, which was a negative energy that formed in the total absence of the goodness that flowed from the Heavenly throne. Normally, an Angel's divine power came to them as they enacted the will of their King. This new form of power did grant them independence from relying on The Creator for strength, but was still remarkably inferior to the divine flame that rested in the hands and on the blades of the Angels' swords.
The Demons formed their own legion, which they called the shedim.