Fallen angels are elusive figures. They maintain their permanent youth and peculiar strength as does any supernatural being, but because they lack a True Angel’s halo or a demon’s Aedifex, they tend to be precariously mortal. All angels get their power from a shared pool, which they access through their halo. An angel is notoriously much harder to kill because of this, while a demon only has the limited power of their aedifex. Fallen angels do not have either. They may or may not have wings, but most often their wings were severed before they left Heaven. They usually aren’t welcome in either Kingdom, not until they either repent and return to Heaven (which is rare) or until they decide to become a demon.
Once a fallen angel becomes a demon, they are permanently a demon. They cannot repent, they cannot return to the neutrality of being Fallen, as they are now permanently tethered to their aedifex.
A fallen angel cannot be summoned or invoked.
An angel may fall for any number of reasons. Most commonly, they have betrayed some law in Heaven and lost their wings as punishment. On very rare occasions, an angel may voluntarily give up his wings. This is uncommon, because it’s considered very shameful and the process of losing one’s wings is just as bloody and painful whether its voluntary or not.
Fallen angels are not inherently evil, but all demons are descended from them. (demons are not inherently evil, either). The most well-known fallen angels are King Lucifer of Hell and his brothers, Samael and Mamonas.
A supernatural astronomical event called a starflood is when a massive number of angels are expelled from heaven at once. It’s called a starflood because a single angel falling to Earth resembles a shooting star to the naked eye (maybe you’ve even seen one without realizing it!), and many falling angels looks like the sky is full of falling stars. Records vary, but there have only been 2-3 starfloods in history, the biggest and most notable being when Lucifer and a third of all angels in Heaven were cast out for their blasphemy.