Demon pact

See also: soul bond

In some mythoses demons, devils or similar entities can enter a pact with a mortal where the supernatural being gives something immediately for the mortal with whom they make the pact with and later the demon takes their price for it (which was declared beforehand or not).

In cases where the demons have almost god/genie-like powers of altering reality with almost complete freedom, the demons are limited to expressing their powers only with pacts and not as they please (requiring the pact to exist to use their powers at all, even if they wanted to otherwise).

Commonly the pact involves some unwanted interpretation of the terms of the pact, the demon somehow turning on the mortal after the pact is complete (e.g. the pact is the only thing preventing them doing in the first place), or the benefits of the pact for the mortal turn out to be somehow malignant to them.