Okay, let's see... Back at the start of the plague, the "Saviors" might have had good intentions. They did manage to save a handful of people, but caught the plague, along with the rest of the town. One of them decided the only way to stop the plague was to drown everyone in the town in their homes, except the handful of rescued and the "Saviors". The handful they saved used magic to prolong the lives of the "Saviors", but couldn't cure the plague. The only way to cure it was pass it on to a relative. [This kinda doomed an innocent person, no?] Over the years any passing traveler who camped in the ruins was taken to be drained to keep the magic sustaining the "Saviors" going. The not-dead-yet Kinlord tells you "The blood Arillas offered us from the outsiders was free of disease, but unsustainable none the less. Faidur will be different." Random stranger blood would keep the magic going, but do nothing for a cure.

His kin Faidur was different because he was a blood relative. The kinlord also tells you it will only take a "few" *generations* of infecting relatives to cure the plague. How many relatives would it take to create a total cure, and how many relatives would be willing to make the sacrifice of becoming a "Savior" to cure relatives who should have died centuries ago, who have been killing travelers and relatives to sustain their lives?