Each of the Arch Fey is unique to the point of no discernible trait shared by even a large number of their race beyond the ability to change their shape at will, though most will have a favored form.
Genetics and Reproduction
The ArchFey are immortal and rarely known to reproduce. They occasionally will breed other races to create half breeds that are left to their mortal parent. Some of these will show enough promise that they are taken and ritually made into a Fey. Archfey have trouble breeding with their own kind and after they left the world it became almost impossible. At this point there are a few methods to create an Archfey but it is dangerous and unlikely at best.
Civilization and Culture
ArchFey often referred to by titles rather than names.
Archfey have few organizations, their own Independence making it difficult to work with each other.
As the Arch-Fey can make themselves appear as anything their ideals in beauty are more toward the how cunning and imaginative their partner can be.
Arch-Fey can take any form or gender and care as much as one would bother choosing between cloths
Relationships between ArchFey is more political and business with each ArchFey trying to seduce the other so they gain an advantage over their business dealings though if mutual love does spark between two Arch-Fey they can be a force to be reckoned with till one or the other eventually grows tired of their love. The one still in love will be take advantage of until all good will is lost and they split.
Being immortal Archfey often are loathe to carry relationships longer than a few hundred years.
Average Technological Level
Archfey were bestowed the greatest gifts of the gods and have magic and technology far greater than any civilization, but their arrogance causes it all to be wasted as the Archfey have not changed much in the eons since the loss of the first world.
Culture and Cultural Heritage
Since their absence from the material realm the ArchFey's perceptions, motivations, and actions have become alien. They seem to understand the world through relatives rather than absolutes obeying a logic opaque to all. While they may sometimes take the form of humanoid-like beings or animals, they are often incapable of understanding mortals. Although they are near god like in power they rarely position themselves upon that level, rather taking on more natural aspects such as incarnations of concepts and events.
The Archfey will not lie and laying with a mortal is now considered Taboo.
Interspecies Relations and Assumptions
The Archfey will attempt to trick non-fey with pacts and subversive gifts.