We, The Infected

Some people believe that Elie controls every man she meets into being a person who serves her. The previous person served her and when she charms Oscars who's to say that he won't as well.

Well, everyone is of course entitled to their own interpretation of the story, but if you ask me, the oft-discussed grooming theory (as it's called) just doesn't hold up to scrutiny, even if you look at the movie in a vacuum and ignore the book and everything that JAL and TA have said. I think a_contemplative_life put it well in this post.

If Eli is so good of an actor, she deserves her human servants and she still wouldn't be evil because she's only trying to survive.

Eli is trying to survive, it's no different from lions, tigers or bears (Oh My!) in the wild.