Consider the idea of spontaneous genesis of life, as used to be belived. What strange kinds of life might arise from modern substances? What kind of vermin would a landfill produce, or an oil spill on the ocean?
A demon who isn't some hideous creature bent on consuming souls, bu is, in fact, a likable chap who enjoys having pleasant chats with people - trying to talk them into becoming his servants.
A planet (or city, valley ect) where those who enter witness protection can escape old age and death itself, so they can live for centuries without aging-provided they maintain their cover perfectly. If they are outed by anyone or ever utter their true name, they age the number of years they have not aged since the day they entered witness protection (which might mean that they age centuries in seconds and crumble into dust and bone.)