Fey

I said to the more powerful of the two sorcerers, "What would happen if one of your spirits had overpowered me?"

"You would go out of this room," he answered, "with his character added to your own."

William Butler Yeats, The Celtic Twilight

Fey are strange nature spirits with close ties to the Feywild. They are masters of illusion and manipulation and generally seem to place great value on nonmaterials such as thoughts, memories, and names. They are chaotic and amoral, with some generally benevolent or malevolent, but most simply self-serving, and all of them are heavily steeped in magic.
Fey operate by a strict code of decorum, to which they hold all creatures with which they interact. Part of this code is the careful keeping of a social balance, which means that once a favor is recognized, it is imperative to return it. They additionally are the only known creatures to innately know the ancient secrets behind the utilization of a creature's true name. For this reason it is strongly advised never to reveal one's true name to any fey, lest they seize partial or total control of one's life.
Fey are exceptionally long-lived and, completely unlike any humanoid race—except arguably elves, the only ones whose temperaments are comparable—they embrace change wholeheartedly. They exist in harmony and cooperation with their native plane, and the prevailing theory is that the departed spirits of fey are reborn in a different form within the plane. All fey seem aware of memories, even a whole life of them, that they no longer have, although it is impossible to know whether this is actually indicative of a cycle of reincarnation (though indeed fey purport to believe that this is something close to the truth) or simply memories that they have long ago bartered away.
The origin of fey is unknown and hotly debated. They are often portrayed as closely tied with the god Uapri, who is sometimes referred to as the Supreme Archfey. They have also been associated with Shej for their chaotic nature, Na-Ima for their influence on dreams, La for their association with omens and portents, and Kan Zul for their association with curses and witchcraft. They have also been compared with devils for their self-seeking nature and emphasis on deals. Some scholars have described them as a class caught between celestials and fiends, with Silaqui Serpenthelm having once written, "Fiends battle for the furthering of evil, celestials battle for the furthering of good, and fey battle for the furthering of anything other than what is."