collider.com has an interview with Stephenie and here is the part about Rob. You can read the rest by clicking the link.
Question: Dealing directly with actors, do you have any connection with Robert?
Stephanie Meyer: A little bit, a little bit. With Rob actually, we sat down and talked about Edward’s character before the filming started and I'd just come in and met everyone. It wasn’t an argument, but we actually disagree on his character. I’d be like, 'No, this is how it is.' He’s like, 'No, it’s definitely this way.' And the funny part about it, you know, is here we are arguing about a fictional character and yet in the performance he did what he wanted and yet it was still exactly what I wanted. So that was really cool.