Who is Seppel the Pelnish Wizard from The Other Wind and what is their importance?

Seppel the Pelnish Wizard is a mage. The wizards of Paln are feared and mistrusted in the Archipelago because they serve the Old Powers of the Earth.... the dark 'cthonic' forces of life and death itself. Seppel is also one of the High King's councillors, and he is summoned to the Dragon Council to tell them what he knows about the ways of Dragons and the dead.