A monster design via  chiger's three words: Cresent/Skink/Inky.

Although they aren't technically a monster (the classification of monsters from animals, civilized species etc is a difficult subject and vary between insitutions and species), the False Cresent Skink has been known to attempt to eat Fae and their high pitched diplomacy is too irritating to ignore.

The False Cresent Skink is named so for it's luminous oils it's body secretes and it's habit of holding itself in a semi circular position on vertical surfaces. In bright light they appear as a somewhat slimy, ink black lizard while in the dark they shine bright enough to attract moths and other insects - their primary prey. They are about as threatening to others as a normal rat (quite a threat to a fae then), and their oils loose it's luminous quality when dry. The same oils also make them taste terrible so they tend to be left alone unless someone wants some fancy living lamps.