The Fey

The Fey are the native denizens of the Plane of the Feywild, sometimes called Faeries. The Fey come in many different shapes and sizes, and are usually tied to the natural world, embodying the energies of growth or decay and the natural cycle. But the Fey are best known for being tricksters and shapeshifters, able to take on both humanoid and beastial forms to serve their needs.
  The Fey are a species of highly emotional and carefree beings, acting on a chaotic whim and pursuing joy and pleasure above all else. Because of this the Fey tend to be very difficult for mortals to truly understand, they seem to be incredibly amoral beings, working on a completely different moral framework than the rest of the Universe. What may seem to be a fun prank to a Fey is seen as a crime to a mortal.
Keeping promises or personal codes seem to be morally important for the Fey. With one of these common promises or codes being to not to tell a lie, but this means that many Fey are very adept at twisting the truth to avoid directly lying. The nature of Fey morality has been studied by many a scholar, and we have yet to come to an understanding, and maybe we never will.
  The Fey tend to have a distaste for technology and industry, possessing an aversion to it. It is unknown why Fey have this aversion, the prominent theory being that it is unnatural and therefore conflicts with their spiritual nature. This has led people, in the Material Plane, to use iron, particularly forged Iron, to ward away Fey from their homes and their children. It is unknown whether this is effective or not.
  Not all beings that reside in the Feywild are true Fey, creatures such as Eladrin and Satyr may be descendants of the Fey, but since they have moral souls, they are not bound to the Feywild the same way true Fey, like Nymphs and Fairies, are. A being of Fey origin can usually be recognised by their pointed ears and otherworldly appearance.
  Language: The Fey speak their own language, Sylvan, which is almost exclusively found in the Feywild.

Biology:

The Fey need to eat, drink and sleep, though far less frequently than mortals. The majority of Fey are ageless while within the Feywild, but they will begin to age if they spend an extended period of time outside of the Feywild, and they will die if they do not return in time.
  The Fey are usually born from the Feywild, sprouting from the natural world, with very few born through reproduction.
  Fey don’t have a concept of Gender and can change their appearance to be masculine, feminine or androgynous at will. Though most will stick to their favoured form.
  Unlike mortals, Fey do not possess souls or free will. They have a set and strict identity and are incapable of true change. All Fey die permanently if they are killed.

Hierarchy:

The most powerful Fey are known as the Archfey. They range in power, with some of the more notable ones being Quasi-Deities with incredible magical power. Many Archfey are members of one of the two courts of the Feywild, while others are unaligned, uninterested in frivolous politics. Archfey are often members of one of the two courts of the Feywild, but many others are unaligned, uninterested in frivolous politics.
 

Courts:

Many common Fey are also subjects of one of the two royal courts of the Feywild, the Seelie or the Unseelie. Both courts reside in separate parts of the Feywild and have an intense rivalry, reflective of the relationship between the court's Queens.
  Members of the courts possess the titles of Lord or Lady (Approximate translation of the genderless Sylvan “Arwein”) and are the most influential members of Feywild society. The courts operate around a complex class system, still not fully understood. It seems to be structured around an individual's reputation and social standing, with a person's public image being incredibly important to maintain. Breaking promises or personal codes seem to be the most damning thing a Fey can do.
  This system is almost exclusively seen within the courts of the Feywild and is rarely seen amongst the Wildfey.

The Seelie Court:

The Seelie Court is usually associated with life and growth and presides over the seasons of Spring and Summer. The Seelie are ruled by the God-Queen Titania.

The Unseelie Court:

The Unseelie Court is usually associated with death and decay and presides over the seasons of Autumn and Winter. The Unseelie are ruled by the God-Queen Mab.