Ok, so i was having a conversation with another huge suikoden fan over a chatlog in world of warcraft, And he was saying how he hoped yuber would be in 4. So eventually we got to talking about these two and their inevitable duel, and why they don't like each other in the first place. So i was thinking maybe at one point Yuber's True Rune got tired of him and saw a good host in Pesmerga. So it did the thing those true runes do and left Yuber for him. But then To get it back maybe Yuber did something extremely bad (or good in the True runes eyes) to get in its good graces and it came back. Now this pissed pesmerga off because he liked the power. So of course i figures the only way to get the rune back is kill him.
i don't know but that could lead into an intresting back story