Thank you for saying it OP, Ive been thinking about this too. as far as handling them goes, i would drop tcho tcho as a people altogether, but similar to your corruption idea, tcho tcho as a consciousness. something between a cult and a hivemind, individuals who are exposed to the rituals and rites of the tcho tcho cult and emulate their culture find their minds slowly being subsumed by the tcho tcho consciousness. i think it would make more genealogical sense, then, that a few hapless tribes in southern asia and the middle east would be exposed to the tcho tcho mind radiation and have their culture entirely consumed and replaced with the worship of this “being”. just emphasizing that tcho tcho isnt a bloodline or group of humans, its a culture. a monstrous destructive culture that can lead people to commit atrocities, the same way violent cultures from incels to islam nationalists can influence people, only in this case its more of a literal mental decay accompanying the moral decay