LA Times Twilight Countdown talked to Melissa and here is what she said about Rob.
Which actor came closest to the character as you envisioned while writing the script?
Billy Burke I thought was just incredible. I wasn't sure at first, because I didn't really have an actor in mind while I was writing Charlie, but he so beautifully embodied that relationship with Bella. He's one that really stands out for me. I was also delighted by Jackson Rathbone, who plays Jasper. He doesn't have a ton of dialogue or screen time, but he just pops. I don't know what it is exactly; he's just got this spark. And Robert Pattinson and Kristen Stewart were also both spot-on.
That’s interesting. Both Robert and Stephenie have said they didn’t see eye to eye on Edward initially.
Yes, that's true. But I liked what Robert did. The tone of my original script was off. It had more humor and he brought it to a more sober place, which winds up being really great and dramatic for the film. He's very elegant in a way. You can see him as this guy who's been around for 100 years; he brings that history with him. It's almost as though he's from a different time. It's really effective.
You can find the rest of the interview here.