Well, I'll give you my version:
We existed with God before the earth was formed. We were the hosts of heaven that shouted for joy mentioned in Isaiah. We were spiritual beings before we gained our bodies. Everyone was there. Jesus, Lucifer, Adam aka Michael, Noah aka Gabriel, etc., etc.. Free agency was and is one of God's greatest gifts (according to doctrine). Even in the pre-existence (what Mormons call it) we had free choice. Lucifer rebelled because he had the free agency to do so. Jesus was the firstborn and Lucifer was jealous. He wanted all the glory but none of the hardships. His idea was to force everyone to follow the Plan of Salvation which would nullify Free Agency. God said no. Jesus stepped up to the plate and took one for the team. Satan got pissed and threw a major tantrum. He bitched and moaned to a third of the hosts of heaven. They said, "come at me, bro!" There was a war. We fought on the side of God ( we know this because we now have physical bodies and are living on earth as mortals). Satan and his followers were sent packing. Without ever gaining a body. They did not keep, what we refer to as, their first estate (remaining in the presence of God). So they roam the earth angry and bitter and seeking to destroy the lives of men through deception and seduction.