Fey
Fey are primal spirits split between the Seelie and Unseelie. Many greenfolk and tuatha are born fey or become fey by being inhabited by these primal spirits. Some druids and shamans borrow primal power from fey spirits while others can literally be possessed. However, many fey are also unseen spirits of forests, lakes, rivers, mountains, and similar places of wilderness. Fey spirits that take physical shape are often called Elementals, Hamadryads, Huldras, Kami, Nymphs, or Skinwalkers, depending on their type.
KAMI
When fey become protectors of a particular river, tree, grove, hill, or similar spots, they become guardians known as kami. Kami are the equivalent of knights or samurai of the fey. They are respected by other fey and granted full autonomy over their domain, only answering to the fey courts that oversee the natural world. Primal warriors who die sometimes become fey spirits and return as kami instead of passing on.
SEELIE
Seelie fey embody artistry, beauty, cleanliness, fertility, growth, health, light, life, spring, sun.
UNSEELIE
Unseelie fey embody darkness, death, decay, disease, filth, moon, rot, shadow, ugliness, and winter.
COURTS
All fey are split into courts that convene during their seasons (Spring, Summer, Autumn, Winter). Each court has 8 elder fey. In addition, there is a fey king or queen for each court that serves as a tiebreaker for all court decisions and passes default judgements at their whims (which can only be overridden by consensus of a court). Seelie and Unseelie share summer and fall though Seelie dominate slightly in summer and Unseelie dominate slightly in autumn. The courts convene in places called "primal warrens" or "fey groves". These places radiate primal energies and are protected by fey zealously using illusions and lethal tactics so that their locations are never known to those outside the service of the courts. It is said that creatures who reside in or near such places become fey over time.
All fey are spirits native to the Fey Realm, also referred to as the First Realm, Primal Realm, Eden, etc. So long as a fey is in the wilderness and not within the borders of an urbanized location, they are treated as native spirits rather than extraplanar. However, placing a fey within an iron, steel, cold iron, adamantine, or similar metal container or shackles treats it as being extraplanar, allowing it to be banished. Killing it with weapons made of such materials also banishes it back to the primal realm and wipes its memories of the material plane. Because of this, most fey see it as a death sentence.