The Zeison were jedi that left the order during the beginning of the hyperspace wars and hid out.  After several generations the Jedi stopped being protectors and were seen as uncaring.  They became very self relient.  When the Jedi found out about them the Zeison saw them as far too eager to take their force sensative children to the temple to make them disciples.<br/><br/>I was figuring he could have had a brother who was taken, he got pissed and followed the Zeison traditions until he left the planet, trying to find a way to stop the jedi from stealing away their familes.  A semi twisted view of things, but it'd give him reason to be with the Sith.