When the crystal norn merged with one of the nu, giving life to the entity known as Atem, all but one norn became corrupted - determined to destroy Atem the only way they could, by destroying the elemental spheres they were created to protect; like an immune system destroying the body in order to fight the disease.
  After the shattering of the crystal sphere and its merger with the stone sphere, the norns focused on depleting the reservoirs of their own spheres. Wood, Water and finally Air all collapsed into merged spheres of Crystal and Stone forming the world of Wyrd. Each norn crossed over with the shattered remains of their spheres to wage war upon the only norn that stood against them, the norn of the stone sphere, protecting Atem and thereby Wyrd, this norn became known as Dvallin.