"The old snake, who is called the devil and Satan, the deceiver of the whole world, was thrown down to the earth; and his angels were thrown down with him."
- Revelation 12:9
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When the human population on Earth grew, sons of God found the daughters of man attractive and took them as wives. This was seen an abomination to God and, as punishment, the sons of God were banished from Heaven and condemned to live the rest of eternity on Earth. Like the Devil, the sons of God were stripped of their angelic auras and their wings.
One angel in particular also took a mortal woman as his wife and was also cast out of heaven, but this angel had the mercy of their Father and was granted to be with his beloved once every century.
Seeing this intrigued the Devil.
He offered to grant his true love immortality, but the angel declined. This did not please the Devil, in fact he became obsessed and swore to make every hundred years arduous for the celestial being.