Board Thread:Lore Discussion/@comment-1852943-20130424155230/@comment-10167444-20130604181446

That's a pretty fair point.

I believe persecuted the Undead since they first started appearing. The reason for this could be that they knew about the prophecy (it seems to be fairly common knowledge, quite honestly) and were afraid that if an Undead got to Lordran they wouldn't continue the Age of Fire. Of course, if no Undead ever got there then the flame would die anyway. Therefore, whenever one of their members went Undead they sent them to Lordran, knowing that they would try to continue the Age of Fire. If they succeeded, great. If they failed, fine, one less Undead to worry about.

Petrus, I believe, is there to ensure the WoW peeps don't screw up and bring on the Age of Dark. Perhaps over time though he got tired of his post, and wanted nothing more than to keep from going Hollow? I feel like he harbors some resentment toward his Covenant, whatever the reason may be.