Having just finished a massive Harry Potter film fest I have started watching the hours of bonus material. Most of it is interesting for mainly the technical aspects of making a movie (although I suspect making a Harry Potter movies is probably unlike making any other movie with the exception of perhaps Star Wars).
In one of the bonus items JK Rowling says that the actors, other than Daniel Radcliffe, were quite how she envisaged the characters appearing which lead me to think a little a bit how I imagined the lead characters. So after several minutes of thought I give you my version of Ron Weasley and Hermione Granger.