“It is better to re enter hell and become an angel, than to remain in heaven and become a demon.”
Vual is a mighty Great Duke of Hell, commanding thirty-seven legions of demons. He gives the love of women, causes friendship between friends and foes, and tells things past, present and to come. He first appears as a camel, then changes to a man and speaks egyptian.
Some demons are worse than others and often the line between angel and demon seems blurred. Illustrate a demon from mythology (the Ars Goetia is a wonderful, weird list to start with) or create your own.