I have loosely based the Sligg Maith on Scottish Fairies. Much of the lore I use in the book comes from, The Element Encyclopedia of Magical Creatures, by John and Caitlin Matthews. Sligg are connected to the earth in a way that makes them a kind of caretaker of it. They often upset human plans by souring the milk before it gets to market, ruining crops for no reason, letting the cows out of the paddock, and etc. They are not beyond getting what they want and will use magic to do so. We are never sure what their capabilities are. They are uniformly good looking, fun loving, and do marry into the human realm occasionally. The Sligg of Ravenheart are not shining and holy, unless they want to portray themselves that way. They can be ornery and unhelpful and in the case of the queen, spiteful and dangerous. They live almost forever, but can die, so war is not something that they try to promote. They choose stealth rather than all out combat but, they are fierce fighters when they need to be.
There are some rules about entering their territory, which is somewhere between the realm we know and what we don’t know. If a human steps into their realm, usually tricked by a Sligg, or innocently through some kind of spacial shift, they may never leave. If somehow they get permission to leave many years may have gone by, sometimes hundreds. If a human and a Sligg marry they can produce offspring. Sligg have been known to steal human babies upon occasion. Because humans are not long living they are sometimes brought back when their beauty or uniqueness is finished. These poor creatures rarely understand what just happened and die very soon after being abandoned by their Sligg family.
Sligg are often described as being fallen angels. Bernie, in fact, describes this story in her own words. So I won’t go into it here.