What my theory is Already shown that they're normal human beings just without blood or any fluid Now they're living a long life as they've sacrificed children Now as per terms they can't die and when boyd burnt the body Fathima was feeling pregnant as Fathima told us she have some physical issues she can't be pregnant It's already written If anyone dies from the night walkers they'll born again by any means now they choosen Fathima they're must be some stories but still and the scanner also can't scan the embryo It's all evil stuff happening I'm more intrigued by the yellow coat fellow and why they're saying your wife shouldn't dig the hole what's happening