The Fates are members of what some people call the old gods. When seen on Alusia, in places like the Temple of the Fates, they often look like three woman of differing ages; Youthful, Middle aged, and Old.
The norns spin the threads of fate at the foot of Yggdrasil, the tree of the world. Beneath them is the Well of Urðr (well of fate) with the two swans that have engendered all the swans in the world.
The Fates are able to change things in the past and make it seems as if the changed thing was always that way. Meddling like this often comes at a heavy price.
GM: For more information or background on the Fates click here.