Agares was king by the time Sasarai was born, so I guess that should be Hikusaak.Maroux was a noble within the Holy Kingdom of Harmonia, but he quenched a rebellion and was granted his own land in return. He was also given the Beast Rune from High Priest Sasarai, which has been passed on through the Blight Family.
Edit: Have been playing Suikoden II a lot at the moment. The info seems to have come from Luc. His exact words are;
"Yes, I heard it was passed down from High Priest Sasarai to the Blight Clan when Highland divided from the Holy Kingdom of Harmonia"
I still don't see how that would work though unless Sasarai was either born much, much earlier than IS 444 or has been time traveling for some reason.