The Book of Enoch - Chapter 12-16

Judgement of the Watchers
Origin of Demons

Chapter 12 – Before the Archangels act, God has Enoch (who has already been translated at this point) declare judgement on Azazel and the Fallen Angels
Chapter 13 – The Fallen Angels plead with Enoch to petition God for forgiveness on their behalf, as they are too ashamed from their sin to do it themselves
Chapter 14 – Enoch sees a vision of God's throne room, with God on His throne
Chapter 15 – God gives Enoch His reply, which includes a sharp rebuke against the Fallen Angels. We learn the fate of their offspring, the Nephilim, which become evil spirits on the earth, ie. demons
Chapter 16 – The Fallen Angels and all the godless have their final fate sealed