

Fallen angels
A fallen angel is a wicked or rebellious angel that has been cast out of heaven. The term "fallen angel" does not appear in the Bible, but it is used of angels who sinned, such as those referred to in 2 Peter 2:4, "For if God did not spare angels when they sinned, but cast them into hell and committed them to chains of gloomy darkness to be kept until the judgment ..." Fallen angels are beings that are corrupting into demons and powers that are corrupting into things far from angelic but not quite demonic. The first known or written fallen angels were Lucifer and his brood that tried to rebel against God during the war in heaven. After being cast into the pits of hell most of his brothers began to take different forms from their falls. While some lost wings to only have one or an odd number, some began to completely look different their powers changing to become the first demons. Another group of fallen angels are known as the Grigori, they fell after lusting for the daughters of mankind. God gave them two hundred years to return back to heaven but sadly only a few went back to heaven. The rest remained upon earth leaving two hundred watchers that would be imprisoned and tormented for the rest of their days after God flooded the earth killing them along with their children.
It's difficult to distinguish between a 'fallen' and a 'rebellious' angel. Fallen angels are those that have defied Heaven's principles and laws, and leave the Host of Heaven permanently. They may be cast out or may leave on their own. Where rebellious angels are those that have questioned or disobeyed orders from their superiors, in particular Michael. They may have created a more personal and individualized agenda. These angels may experience a demotion from their original ranks in the angel hierarchy, and would then be placed in a lower angelic class. True rebellion, meaning outright disobedience, is considered to be closely associated with a Fall, except they do not have to option to leave by their own will, rather their wings ripped from their backs to leave scars by an Archangel (most likely Michael) and fall to and be trapped in the realm between Heaven and Hell.
Lucifer: Lucifer was expelled from Heaven by God and eventually cast into a cage in the deepest part of Hell by Michael. His contempt for humanity and the creation of Lilith, the first demon, led to his fall. He is the 'ruler' of the Daemons, and is much like the God of the underworld. He is the original Fallen Angel.
Angelic Rebels - the Fallen: The Fallen were those who believed in Lucifer's rebellious disobedience, and believed that Heaven was not in the right, but the wrong. These angels fell with Lucifer and were sent to Hell along with Lucifer and his Demons. These angels have equal angel-like powers, although they carry more dark properties and hidden hellish motives. Their powers resemble that of a regular demons abilities as most fell to become Arch-daemons or regular daemons. They had their wings ripped from their backs, leaving the stereotypical jagged demon wing to protrude from their backs.
The Egrigori - The Watchers:
Angels that fell after the fall of Lucifer: These angels fell from Heaven for their own selfish reasons. They either disobeyed the laws of Heaven, or had equal desires that mirrored Lucifer's. These angels have mirroring powers to those of the angels who are still in grace, until they choose which side they desire to convert to. If they lean towards Lucifer's side they gain more daemonic powers than those of the angelic. Fallen angels still have their feathery wings, unless they are considered a rebel to Heaven in which case their wings are ripped from their backs and they sport a 'V' shaped scar where their wings should be - should a human or non-angelic being touch these scars they will be thrown into the worst memories and desires of the fallen angel. The angels with wings ripped from them do not gain the fashionable demon wings that's all the rage in hell. Those who still have their wings, only chose to leave Heaven to dwell upon the Earth. Sometimes they return to their Heaven and sometimes they remain upon the Earth in peace. These angels have angelic abilities and powers, the only downfall is that they do not have the same Holy fire as they would if they chose to remain residing in Heaven.
Powers:
Fallen angels are able to keep some of their powers while others begin to turn. It's a long list so this wiki shall go over the basics and dwell into some of the more sophisticated things on what fallen angels are able to do. God originally created his Holy angels, who were capable of carrying out certain tasks for God. Those who have fallen have lost merely their holy path. These tasks of the holy angelic beings included giving messages, through dreams and visions, or delivering a message while appearing as a man. Though they usually remain invisible, angels protected people from harm (Psa 91:11-12). They function as the army of God (Rev 19:19): they destroyed Sodom (Gen 19), brought down the wall of Jericho (Josh 5-6), and smite people (1 Ch 21). God created angels to be able to do things like these.
Angels can do miraculous supernatural things, and fallen angels can still do many of these same things, as they were created with these abilities. But as they have fallen the motives of using their holy powers become corrupted and they then use their abilities for evil and deception.
Pagan gods aren't exactly gods, instead they are extremely magical beings of strange origins. When God himself created magic and it was placed upon the earth, the magic flooded throughout the universe through the hands of the one true God. Though upon earth it also formed in places called Ley Nodes, which are immense sources of magic that draw demons and supernatural beings to them. It also draws in mortals, now during the early ages of what some refer to the lost era. Where humanity left the teachings of the Abrahamic faiths and formed the pagan faiths of the Norse, Greeks, Romans, and many other groups their stories caused the some what sentient magic to form new beings. These realms the humans told stories of to make sense of their existence instead of following the true faith of the angels began to form. The magic began to branch off through the universe and create new realms, such as Asgard, Olympus, and the other realms that came along with their existence.
The only powers these pagans DO NOT have would be death, creation from nothingness, and the ability to erase entire dimensions as stated in some of their sources. These powers still remain to heaven and hell alone, though beings like Hades do hold power over the passed souls that held faith in these beings. Thus actually ushering them to the realms for the undead in the pagan lores, they shall remain there until the entire universe is reaped for what it is is worth by heaven in the end days.
Now, these beings are immortal to age but can die by the weapons forged from their own metals, the metals of heaven or hell. Even extremely powerful mages, warlocks, or other wielders of magic or powers above them may destroy pagan gods. Thus ending their existence and causing a rift within their realms, this is the most likely cause for them not siding with neither heaven nor hell to save their own skins. Demigods: Demigods are the children of humans and pagans, thus creating a mortal being that has the powers or gifts of their parental figure. Say, those that are the children of Zeus would be able to control wind and lighting, Hades the ability to use necromancy, etc. These beings are protected in the mortal realm by Clave laws and are seen mainly as neutral members of the supernatural society, the Clave does not tend to interfere with the demigods unless they begin to break the accords.