The Kingdom of the Fae is one of the most treacherous pieces of geography in the Treacherous Lands. A traveller may approach it by several routes while in those lands, but none of them connect up in the normal spatial sense. It also seems to occasionally and randomly appear at other points in the treacherous lands where it wouldn't normally be found. Some speculate that the land actually exists everywhere in the world, but finds it easier to manifest some places than others - particularly in the Treacherous Lands. This is borne out by the fact that, at certain times of year, it can actually be reached from certain ancient sites in the True Lands. Once in the country of the fae, a traveller will notice that its internal geography displays no more constancy. A few sites, such as the Lancing Glen and the Royal Forest, seem to stay the same, but their relation to each other changes on a daily basis, and other parts seem to slip in and out of existence continually. Some sections of the country seem only to take material form when a human visits, and shape themselves around the traveller's perceptions. In the early days of the Empire, the Emperor discovered a number of the paths from the Kingdom to the True Lands, and realised that this was a means by which the Powers had bypassed the Wall. He set great standing stones to seal some of the paths to the Kingdom, and covered others with enchanted earthen mounds. Unfortuneatly the enchantments on these gates faded with time, and now they serve only to mark where the paths to the Kingdom lie. It is also said that paths to the Kingdom can appear in the dreams of humankind; a few books have been devoted to the subject of how to 'dream up a fairy servant'; in fact, this is a dangerous and silly thing to attempt. Humans may travel along the paths to the Kingdom; all that is required is to stand at the start of one of the paths, desire to travel along it, and step forwards.
The Fae are said to be born of all the Powers and were led to put on humanoid appearance after the Intercession to mock the Gods. Fire, though, is certainly their favorite parent. Like their land, they have few fixed qualities, and do not bother with material forms when they don't have to. Many like to use the ancient paths to visit the True Lands, where they adopt a variety of material forms ranging from beautiful to hideously ugly. Each fairy has one favored form for use in the True Lands that reality forces it to stick with, more or less. There they use humans (or whatever is to hand) for amusement; this occasionally consists of impregnating humans, or swapping human babies for fae. Most of them don't use magic as it would be recognised by humans; they just aren't as closely constrained by physical laws as others [I suggest that fae 'magic', such as it is, be handled freeform by the GM team and be reasonably weak in the True Lands; it would then be stronger in the Treacherous Lands, and stronger yet in the Kingdom of the Fae]. The Fae are somewhat resistant to god - related magic.
The fae are ruled by a Queen; she has many names, few of which are known to humans. She is attended on by many courtiers, and is served by an order of knights, who keep the borders of her realm free of the various horrors of the treacherous lands. The fae Queen has done various deals with gods on behalf of her people (the fae never offer a god worship, except in mockery). Lady Illaria is acknowledged by the fae, and is believed to be a friend of sorts to the Queen. A deal with the Toolmaker ensures that the Fae knights are armed and armoured by the considerable talents of the Smith. The Queen is the favored daughter of the powers, and in her own realm is more powerful than any single being short of a manifest god.
Human stories of the fae Queen inevitably include the fact that she is awaiting the return of her husband, whom the fae refer to as the 'Prince Consort'. What hardly any human knows, and what most fae have forgotten, is that the Prince Consort is not coming back because he is walled up in the Imperial War Room. No war has occured between human and fae since the early days of the Empire, and that is because the Emperor made a peace treaty with the Queen that was sealed with their marriage. He did not see fit to inform his people of this; most of those humans that knew are long dead. As far as the Empire was concerned, the Kingdom of the Fae was an Imperial Province by marriage. The fae, in so far as they knew or cared, tended to take the opposite view.
Any number of books in the True Lands are filled with spells that claim to be for the summoning and control of Fae. They are all nonsense. A fairy can be attracted by standing at a point where the True Lands and the Kingdom touch, and calling the name of a fairy. One must then hope that the fairy hears, and decides to answer. Any other rituals will only serve to draw attention to one's self, which may be a good thing, or not. There are no specific rituals to bind them (though binding magic that works on other creatures is equally applicable to the Fae). A fairy may agree to do service in return for a favour; keep in mind that they're mostly interested in having fun. Some, though, have more serious aims; they recall the history of their race, and seek to work against the interests of the Gods, or to spread chaos and magic in the True Lands in the hope of making them more like the Treacherous Lands. Ultimately, they would make the Wall a meaningless monument to the failure of the gods.
A little known property of the Kingdom of the Fae is that slowly, it spreads. This is true in the Treacherous Lands and the True, but in the Treacherous Lands it is driven back by the other unnatural manifestations of those lands. In the True Lands, each use of Fae magic and each call into the Kingdom strengthens the ties to the Kingdom a little. Several Fae encourage this whenever they can be bothered.
The fae can make interesting allies, and even more interesting enemies, if one can just get their attention. In addition, the unusual properties of their kingdom has attracted increasing attention in the True Lands of late. Apart from this, fae are potentially immortal. Those that can be bothered to remember anything may know lore of gods and magic long lost to man. This is particularly true of their Queen...