Not sure if I already said this, but this is a theory. When Moe was sitting with Cnaiur after he'd been stabbed, his snakes were rubbing Cnaiur's head and Moe said something like 'I need your strength'. I believe Moe intended to drain Cnaiur of his life force to enable him to translate his soul into another body. When Cnaiur chorae'd him, the process was incomplete. That other body was Meppa. Moe's psyche (or whatever) partially imprinted on Meppa's causing him to not remember who he was. Also, maybe it gave him his vast knowledge of the psukhe, allowing him to become the badass cishaurim we all know and love.