Grand Duke Kador was at one point the head of the House of Vordue, one of the houses involved in the political intrigue of vying for the emperor's throne. He wanted to succeed Ran Borune XXIII as the emperor of Tolnedra, and had allied himself with Chamdar/Asharak. Kador was the favorite to succeed as the emperor.
Kador had intentioned to dose Ce'Nedra with a rare Nyissan poison before she ran away. Upon capturing her and Garion as they left the Wood of the Dryads, he planned to be "more direct" with a sharp knife. Kador mentioned that the House of Vordue was not interested in marrying dryads and was keeping its line pure and uncontaminated.
After Chamdar was conflagrated, the Tolnedran legionnaires were frightened into some semblance of loyalty to the emperor and arrested Grand Duke Kador for high treason.
In the Magician's Gambit, Kalvor the Tolnedran merchant mentions to Silk that "Kador fell upon hard times" and that the Emperor was going to take steps to remove him from the race.
In King of the Murgos, the Tolnedran customs agent mentioned that "All the brains went out of the Vordue family after the Grand Duke Kador died."
In Polgara the Sorceress, Eddings mentions a Kadon, an ordinary Murgo emissary wearing Tolnedran garb ("pale blue Tolnedran mantle") and then abruptly switches his name to Kador.