The Fair Folk, short for "Fae", are called "the Fair Folk" not because they are nice or beautiful but because it is feared that they will be wrathful if they overhear mortals speaking ill of them. Native to Fae Home, the Fair Folk collectively include many different sub species and a myriad of competing courts, philosophies and other factional divisions which are mostly either completely unknown to mortal kind or hidden behind a shroud of legend, fabrication and outright lies. Thus interactions between Fae and mortals are very hard to predict or even understand. It is believed that the Fair Folk have some distant form of kinship with the Spirits of the Nine. Both Fae and spirits are intimately tied to but not native to the material plane. Both seem to be at least somewhat vulnerable to cold iron and are at least inconvenienced by lines of salt if not stopped outright by salt. Like many spirits, many Fair Folk are vulnerable to odd superstitions unique to some Fae but not others. A great many Fae have direct metaphysical ties to one or more of the classic elements of fire, water, air and earth affecting both their appearance and the nature of their powers.
Growth Rate & Stages
While the Fair Folk like to be condescending to "mortals," the Fae are not themselves immortal, not really. They are very long lived. Most Fair Folk are at least vaguely humanoid and go through stages of infancy, childhood, and adolescence. Then they linger as adults in their physical prime a very long time. Even the shortest lived Faerie races can expect to outlive two centuries. Whether it's after 250 years or 2500 years, a Fae will eventually enter a "twilight state." The Fair Folk will rapidly lose his or her mental faculties and devolve into an animalistic or bestial state. Their bodies will then change to match. Fae call these beings @Remnant which usually take the form of highly unusual plants or animals. Fair Folk slain by violence do not seem to leave remnants, but many Fair Folk believe that slain Fair Folk will still reincarnate in some form, it's just more subtle than a Fair Folk who enters the twilight.
Civilization and Culture
In the Age Before Ages, the Nine and the Traitor , aka “the Ten” were Turoch's primary servants. Turoch had hundreds, perhaps thousands of lesser servants. It’s not clear what form these servants took. Some say that these lesser servants were mortals that were part of Turoch’s soul farm, they were just privileged slaves. They were still eaten by Turoch but before they were eaten they were given power over the others. Others state that these were immortal beings of the same general essence of the Ten, just much weaker. Whatever these lesser servants used to be, when the Nine fought Turoch and the Traitor during the Divine Rebellion , most of the lesser servants chose to be neutral refusing to side with Turoch or the Nine. The vast majority of the surviving lesser servants of Turoch were the precursors of what are now known as the Fair Folk or simply the Fae. The Nine could have destroyed these lesser servants of Turoch who refused to join the fighting, but at this point most of the Nine were tired of fighting. Also, while the Nine had the upper hand, their upper hand was not so strong that the precursors to the Fair Folk did not have the potential to cause the Nine and their new world great harm. The Nine basically let the Fair Folk inhabit the ruins of Turoch's palace/realm in exchange for an understanding that they would not interfere in the Nine's business in the mortal plane. The Fae took up residence in Turoch's home plane, because that is the sandbox they were allowed to play in. The realm is now called Fae Home. Since almost everything in Turoch's spiritual palace was demolished, the Fair Folk rebuilt Turoch's home plane from the ground up in their own image. They set up a link to the Elemental Plane to both provide building material to work with and to sustain their own sustenance. During the First Age, not many of the Fair Folk dared to challenge the détente that the Fae would stay in Fae Home and the mortals would stay in the Mortal Plane. There wasn't much incentive to cross over because both mortals and Fae had everything they could ever want or need on their side of the fence. Of the mortals of the First Age, for the most part only the dragons had the power necessary to enter Fae Home, and very few did so. The Fair Folk and dragons that crossed into "the other world" were mostly hyper curious explorers, dumb adolescents tampering with power beyond their ken, or criminals and pariahs who were looking for an escape from their home societies. This means that the dragons and the Fair Folk saw the worst aspects of the other culture and these views spread through their tales. Even many thousands of years later, modern dragons and modern Fair Folk distrust each other. The relative peace and stability between the Fae and Mortal realms came to a crashing halt with the First Unmaking. As elemental energy washed over and reshaped the mortal plane, the Fae Realm was hit at least as hard. The Fair Folk’s elemental powers were destabilized. Most of them became weaker and all of them had less precise control over their powers and forms. Many Fae died or were horribly mutated. No longer able to meet all their material and energy needs from the Elemental Plane, the Fair Folk were now forced to interact with the Mortal Plane just to survive even if this violated their understanding with the Nine. The First Unmaking completely destabilized Fae society, but they hardly emerged unscathed from the Second Unmaking either. Many Fae lords and ladies were of the opinion that the Nine came off even worse. After watching Void demons destroy many spirits and the Nine's beloved mortals, seemingly with impunity, this has emboldened many Fair Folk to no longer fear the Nine's wrath. While they were forced by necessity to interact with morals during the Second Age, but the Fae usually acted subtly and with great caution. During the Third Age, the Fair Folk tend to be much more brazen when they meddle with the affairs of mortals.