What function does Beelzebub serve in the poem?

Beelzebub is Satan's second in command. He lifts his head to see his second in command, Beelzebub, the Lord of the Flies, who has been transformed from a beautiful archangel into a horrid fallen angel. Satan gets his bearings and, in a speech to Beelzebub, realizes what has just happened: Satan, presuming that he was equal to God, had declared war on the creator. Many angels had joined Satan, and the cosmic battle had shaken God's throne.