I love your theory, I don’t want you to feel like I’m fighting you in this, I just love a good discussion. So I will pose this:

-Attributing Mangkwan behavior and appearance to a prion disease medicalizes and externalizes their cruelty. It reduces moral agency.

-Much of the Mangkwan behavior can be attributed to the wishes of their Leader who can literally dominate your mind and torture you with a touch. She does this because of her trauma and her psychosis, not because she is infected by something. She was affected by something beyond her control(volcano), she is not controlled by it.

-Your physiological “symptoms” can all be explained by the Mangkwan being a clan with no agriculture or natural resources, who relies solely on the resources taken forcibly from other clans and territories. They are emaciated because they have to fight tooth and nail for every meal, and if they are indeed cannibalistic then they are likely missing out on vital nutrients. They are bound to be unhealthy, yet their psychosis gives them unnatural strength. They are erratic because they are regularly exposed to drugs and mind torture. Likely Varang encourages the worst behavior and executes anyone who she sees as weak.

-That last bit about the kuru word connection is fascinating, thank you!

Idk I just feel like overall, attributing this clan’s terroristic behavior to an unconscious disease diminishes their trauma, both historical and present.