It would be a challenge to see if we could end the novel without her dying. Or killing the priest in self defense. I see naivety being achieved using her age. Not too young, the whole priest-child ordeal would distract from the story.
Maybe the epiphany doesn't "resolve" the priest in a sense. He gains insight into using both traits to his advantage. Turning them on and off at will.
I guess it depends on the message being sent to the reader.
Nightmares. He definitely needs to have nightmares.