The supreme being Scioris in the beginning of time created the High Deathless to rule over the other deathless and the mortals. He inititally created Thane, Siris, and The Worker of Secrets to form the High Deathless.
History of the High Deathless
Scioris placed Thane as head of the High Deathless and their Castle "Saranthia." Scioris also ordered The Worker of Secrets to forge the Infinity Blade as a way of channeling his power to the mortal realm. When Siris went insane with power he betrayed the High Deathless and became a tyrant over the other deathless and the mortals. He was everually defeated by Radriar where upon he was made a deathless and allowed to take Siris place in the High Deathless. But he too betrayed them after he was consumed with his newfound deathless powers.