Fallen Angel is one of Three Faction
Fallen Angels are Angels that have fallen from the grace of God, due to having "impure thoughts" that divert them from the teachings of the God in the Bible. The leaders of Grigori were tempted by human women and had fallen after having sex with them.
Despite being cast out of Heaven, Fallen Angels and their subordinates have been known to occupy churches and use them as bases. However, they go out of their way to destroy all of the religious icons in these churches in the process.
Currently, the Fallen Angels have the smallest population among the Three Factions.