I got the quest from Peryite to go and kill Orchendor. In the words of Peryite himself: I sent a blessing to Mundus, a wasting plague that infected a scattering of Breton villages. One of my monks, the elf Orchendor, was sent to gather these Afflicted. He shepherded them into Bhtardamz for me, but has since lost his way. I will not stand for betrayal. I want you to go to Bthardamz and kill Orchendor, in my name."

I sneaked my way in. Now I am lurking in the shadows, with Orchendor in front of me. Should I kill him or nor? I can't decide.

I'm playing a good character, who is not interested in rewards and such. He feels sorry for the afflicted, poor sods. I have no clear picture of what had happened. Apparently Peryite made them sick, and Orchendor gathered them and lead them to Bthardanz, where he keeps them in quarantine, which seems to be a good thing. In what way did he betray Peryite? And does he mean well or not? I read whatever I could find by googling it but I get no clear picture. I tried talking to Orchendor but he has no dialogue.

Does anyone know more?

I think Peryite intended for the Afflicted to be held in Bhtardamz until the time was right for them to be released as a mass outbreak of the disease. However, Orchendor seems to have decided to keep them in quarantine so as not to spread the disease at all, thus betraying Peryite.