Mark McElroy#WritingWonders 5 - Does your antagonist have any moral boundaries they would never cross?
In #Parallel Lines, Davina's mission --her reason for being! -- is to prevent anyone from making changes that would alter the consistency and history of the universe we live in.
So: no boundaries. She's friendly and BIble-quoting ... but if you try to alter history or the future, she will hunt you down and slaughter you without remorse.