Reasoning:

When you start the first game, the Patapon tribe was barely surviving, surrounded by the Zygoton tribe, they were outnumbered and starving. Their god appears and they have hope again, so they decide to go accomplish a prophecy that basically says "go to Earthend, witness It and you'll have eternal bliss".

On the other side, the Zygoton tribe have a prophecy that says "If the Patapons reach Earthend, the Zigoton empire would be destroyed" so you'd understand that they don't want to give too much freedom to the Patapons.

So at some point, in a small watch tower, Aiton and Makoton see the Patapon tribe marching on, and Aiton sends Makoton to go warn the General. Makoton hesitates, then witness Aiton being killed. After that, Makoton's hatred for Patapons is so big that he gives himself to evil forces (once per game) if it can give him the strength to crush the Patapons for good. On the last time though, he was supposed to be amnesiac, he ends up remembering, so his own teammates murder him.