It is an interesting possibility that Vlad Norathar may have the reincarnated soul of Kieron the conqueror. (Kieron having told Aliera that he would return to the land of the living if she gave away his sword, which she did in Dragon.)
This would be especially ironic, since Vlad Taltos himself is the reincarnation of Dolivar, Kieron's brother, who betrayed him. It would be even more ironic if the great conqueror of Easterners reincarnated as one.
Another line of speculation is that Vlad Norathar may be the reincarnation of Franz. There are serious issues as to the timing of the conception of Vlad Norathar, but if Franz was hanging around as a ghost because there were no pregnant Easterners around, at some point at roughly the same period there is a pregnant Easterner very nearby: Cawti.