Ahir is the original creative energy of the pantheon of The Old Gods. It is genderless, and is usually described as having no physical body, with the main exception found in The Creation Story (old gods), where it is described as having one great eye, and the ability to listen, to laugh, and to wield runes.
Ahir holds no dominion over any one thing, but is instead representative of everything within the worlds, and is often shown as being revered by the gods it created. As a result of this, Ahir is held in the highest reverence, but is rarely worshipped directly.
Those that worship Ahir are called Panoptics, and are generally very rare indeed. In order to become one, they must first locate one of the five Panoptic Temples, which is no mean feat. The Temples are located in the furthest reaches of the globe, but their locations are known only by their members, though some suggest those with political or religious power are privvy to their secret locations.
While almost nothing is known about their Temples outside the order, nothing at all is known about their ceremonies and rituals by those outside their number. Those that care to think about what the Panoptics do surmise from stories about Ahir itself that they would not be involved in any kind of sacrifice. Other than this, nobody has any clear idea what way they worship.