In my essay The Fallen Angels and the Goetia in the anthology Both Sides of Heaven, I discussed how in some of the grimoires the idea is posited that demons are fulfilling a role dictated for them by heaven. Thus we see, e.g. in Sloane MS 3824,
“O All you Spirits of great power Lucifer Beelzebub Sathan unto whom By Orders & Offices, as Messengers of wrath,& Ministers of divine Justice, the Execution of God’s Judgements are committed, & accordingly at his Commandment by you fulfilled, on all sublunar things, Creatures & places whatsoever & wheresoever he shall decree and appoint the same to be inflicted”
A reflex of this is to be found in the Goetia, where nineteen of the seventy-two spirits are described as fallen angels, with many of their subservient spirits also described as previously belonging to angelic orders, with four hoping to return to grace, i.e. back to the heavens, after 1200 years. This might be seen as indicating a period of time fulfilling a role, after which ‘promotion’ back to the more pleasurable heavens could be earned.
So although it is well accepted that angels fulfil specific roles under divine dictate, perhaps it is time to accord demons the same perception, and remember that gods are not always nice, sow hy should the roles given to their servants be so!