In
The Wheel of Time, an inhuman race of creatures that resemble humans but have a manner of speaking, way of moving and face that resembles a snake. They also might be somehow related to
Eelfinn.
Nothing is known about Aelfinn's actual life, only about what their dealings with humans: people go to Aelfinn to seek answers. According to ancient treaty, any man (or woman) may enter once in his/her life, having no instruments of music, iron or items to make fire with. Then three questions may be presented to Aelfinn, and they will answer these questions truthfully, if a bit unclearly.
It is not known what Aelfinn gain from this deal; nothing seems to be taken from the humans. Maybe it's their pastime amusement.
It is also notable that the questions may not involve anything touching Shadow; asking these questions may be dangerous. This might tell something about their methods of reading the future. Also, ta'verens have somehow strange effect to that land; when two ta'veren were simultaneously inside the place, it almost went down in earthquakes.
The land that Aelfinn reside is strange place; it might be generated on the fly (like CGI-produced pages); its geometry is screwed and two persons entering place pretty much same time have no sight of each other, at least when leaving.