The tall man in the black suit, raged.
If angels are raw, genderless, impersonal forces of Creation moving between realities, oblivious to everything they touch, then demons are angels that somewhere in their infinite existence, developed personalities.
And rebelled, meddling in the affairs of Creation, a poke here, a poke there, a step back, and let's see what happens, shall we?
All the while, taking form in order to meddle, to feed, because unlike angels, a demon needs to eat.
But unlike the finite mayflies demons mingle among, demons can wait a long time in order to feed.
Consummate gourmets, demons prefer a long wait, refining their hungers, their appetites, honing their controlled gluttony like a fine blade. Demon that he was, the tall man in the dark suit had waited long enough. Had the mortal he contracted with generations ago been a bottle of wine, he could easily be said to have developed a bad case of "cork taint" in the last century or so.
Time to call in the debt and insist upon payment in full.
But first, the tall man in the dark suit, though reluctant for their own reasons, for demons, as angels, are sexless as well as genderless unless they make the effort, had one final contractual obligation to fulfill.
And their petulant child of an elderly master trapped in a young body, would be forced to accept the long-delayed consequences of a long-ago bargain made unwisely.
