Who is Satan's proverbial "right-hand man"?

Beelzebub is Satan's right-hand man, having been the first to side with Satan against God the Father during the war of heaven which takes place before the beginning of the story. Both of them are charismatic and seemingly reasonable leaders who can sway the masses in hell with their pretty speeches and calm manner. He appears to be the most diplomatic of the angels, trying to get everyone on the same page, particularly with making Satan their leader by flattering him before all of them.
Beelzebub is forever destined to be in Satan's shadow. While the other devils are lesser in stature and charisma, they are at least individuals. Beelzebub just copies Satan and agrees to just about everything he does. However, this does not seem to bother Beelzebub in the slightest. He is loyal to Satan and unlike Satan with God, he never seems angry about being lesser and never seeks to usurp his position from what we read.