The Veilkeepers are the order that raised the fog over the Foggy Isles and have kept it standing ever since. They are water-shapers first and brokers second, though the brokering is what pays. Outside their own waters they wear no colors and claim no nation. A Veilkeeper is known by what they will and will not do. They will hide you, carry your message to an enemy under a guaranteed truce, and hold your secret against the day you need leverage of your own. They will not take a side.
The first veil was the work of one water-shaper, Sevrin Calder, who came to the isles with a price on her head and no intention of paying it. She raised a fog to hide a single ship and never let it down. The order grew up under the cover she made and took its first rule from the bargain she struck with the next fugitive to arrive: shelter for a secret, silence for silence.
The standing veil
The fog over the isles is a standing water-Kethic working, not weather. A seam of the water layer, the Pelus, runs close beneath the islands, and on a seam that deep, pressing fog out of the cool sea air costs a shaper almost nothing. The keepers call the seam the Sodden Seam, and living over it is half of what makes the order what it is. No single shaper holds the whole veil. They work it in rotations, a watch at a time, each renewing the bank over their stretch of water before a midday sun can thin it or burn it off. Water answers grief and longing and the yielding kind of calm, and fights a forced or angry hand, so the order trains its shapers toward patience and away from temper. A bitter keeper makes ragged fog. The cost is paid in feeling and not in flesh, and a watch's rest returns it, which is the only reason a handful of people can drown an archipelago in mist for a century and a half without burning themselves hollow.
The veil does not lift. Ships that wander in without a Veilkeeper pilot do not wander out. The safe channels are charted in no book but the order's, and the order does not sell the charts. It sells the pilot.
What they sell
Anyone who needs to stop existing for a while can buy a place behind the veil, and the price has two parts. The first is paid in coin or goods or labor, and it is steep. The second is paid in truth. Every guest gives up one real secret at the edge of the fog, told to a keeper and to no one else, before they are let in. The order calls this a keeping, and it is collateral rather than blackmail in the ordinary sense. As long as a guest holds the peace, the secret stays in the vault. The day they break it, by knifing another guest or selling out the isles or guiding a fleet to the edge, the keeping is spoken aloud to whoever it would hurt most.
That vault is the order's real trade. A body that has taken one true secret from every desperate person to pass its gates for a century and a half knows where a great many other bodies are buried, in several kingdoms at once. The Veilkeepers rent that knowledge sparingly and never all of it. More often they rent the fog itself as ground. Two enemies who can be seen meeting nowhere else meet on the isles under a keeper's truce, each having surrendered a keeping that guarantees neither will start what they cannot finish. The northern Western Isles have no court, no congress, no neutral capital. The Foggy Isles are where the business that cannot happen in daylight happens instead, and the order's fee for hosting it is what keeps the order fed.
The keepings are held by the people least able to spill them. The Veilkeepers shelter the Yngli, the silenced cyclops-kin who drift to the isles to escape the men who work them elsewhere, and they have found in them the surest keepers a confidence could have: a people bound by an old Deoric curse to a silence that breeds true, who could not speak your secret aloud if their lives turned on it. A Yngli keeper takes a guest's truth in gesture and a written cipher and files it where only the order's own can read it. In return the Yngli have, behind the veil, the one thing the rest of the world denies them. No one can talk over them here, because no one is permitted to talk their way past a keeping in the first place.
The standing threat
Tarkhon has spoken more than once of resolving the Foggy Isles the way it keeps threatening to resolve Tollgate at the mouth of the Sound. The arithmetic is worse here. A fleet can blockade a fortified island it can see. It cannot fight fog. Warships that enter the veil lose each other inside a mile, take the channels wrong, and ground on rocks the keepers know and they do not. But the deterrent that actually holds is not the mist. It is the vault. Somewhere in the order's keeping are the secrets of Tarkhon's own people: exiles who fled the empire, agents it would rather no one knew it ran, magistrates who bought silence on the worst day of their lives. The order has made sure the right people in Tarkhon understand that the isles falling and the keepings spilling are the same event.
So the threat is renewed every few years and acted on never. The Veilkeepers prefer it that way. A standing threat from Tarkhon is the best advertisement the sanctuary has, proof that the fog is worth an empire's fear and that the only safe side of it is the inside.