Purrgy

It dozes away most of the day curled in warm patches that no living cat would find, half-materialized on a sun-warmed sill or the top of a cooling stove, purring to itself. It feeds on the calm contentment of the households it haunts, growing more solid and more present the more at ease its unwitting hosts become, so that a happy home may find itself with a faintly visible kitten it never took in. Roused, it flickers out and reappears a few feet away with the lazy insolence of any cat, and it has a way of curling up on the laps of people who insist, firmly, that they do not believe in it.