With 'The Host ' I think the actors could be really big names. That would be cool. I'd love to see Robert Redford put on a beard and be Jeb he would be amazing... Matt Damon has some very Jared-esque qualities and then Casey Affleck as Ian and Ben Affleck as Kyle. Imagine the interplay.
It appears to be a law that you cannot have a deep sympathy with both man and nature.