Beelzebub is presented to us as the second-in-command of Satan. He is the very first fallen angel to come to after the shock of being expelled from heaven and sent down to the fiery land of hell. His value and significance in the epic is linked to the character of Satan. As the first to join Satan's rebellion in heaven, it seems only fitting that he is the second-in-command, and the first of the fallen angels to form an audience for Satan's musings on his new identity and home after his failure to conquer God.
Also, if we examine his role and what he does, he seems to be content to copy the behaviour of Satan. For example, in Book II, at the council of the fallen angels when they discuss what they can do, Beelzebub is happy to be silent and to let others voice their opinions. As the final person to contribute any ideas, he speaks in a serious, majestic voice that shows his charismatic personality and contrasts him favourably with the other fallen angels who voiced their ideas. He is therefore a master of diplomacy and loyal to Satan, as he effectively manipulates the other fallen angels into accepting Satan's plan for gaining revenge against God.