As Harry Potter and The Half-Blood Prince heads into another lucrative stretch expected to add mightily to its $421 million US take worldwide, the young cast reflect on their good fortune to have a creator who is film flexible and novel prolific.
That would be J.K. Rowling who wrote the series of Potter books which have sold more than 400 million copies and created a multi-billion dollar movie world of fantasy and adventure.
"She's always been very, very good at letting go of the films and realizing that they're totally separate entities from the books," says Daniel Radcliffe during a New York interview before The Half-Blood Prince opened July 15.
He's grown up playing Harry Potter, and had to mature with it as the Rowling novels, and subsequently the movies, became darker and more threatening. And more popular.
By the time The Deathly Hallows film versions of the book arrive, The Half- Blood Prince will be the billion dollar record setter.
Chances are the two separate Deathly Hallows pictures - set for theatres in November, 2010 and the other tentatively ready for July of 2011 - will out do The Half-Blood Prince.
Both novels set publishing records. The movies are expected to break box office records, too. The stories live in two different narrative worlds.
And that brings us back to Rowling's sensible approach.
"She's not been too precious about anything," suggests Radcliffe who points out screenwriter Steve Kloves and director David Yates had to undertake a massive story edit of The Half-Blood Prince to make a workable movie.
"She realizes that things have to be cut in order to make them viewable," he adds.
Radcliffe, (Emma) Watson and (Rupert) Grint look forward to the author's set visits as though they were a blessing, not a duty.
"It's a pleasure and a rare treat because I don't think she wants us to feel that she's come kind of prying," reports Radcliffe. "She's always been wonderful and is an incredibly gracious and lovely woman."
As they head toward the end of filming the Potter series by early next year, Watson says she'll miss reading the books as much as playing the character with her mates Radcliffe and Grint.
And Watson agrees that she was always impressed with progression of the novels and looked forward to the next one.
"I'm such a geeky Harry Potter fan, genuinely," Watson insists. "I know the books inside and out and have read each of them at least three times and could probably answer any question you come up with and any plot detail you might care to ask."
And for the record, Radcliffe adds this about Rowling: "It might be interesting to note that the only thing thus far, in six films, that has been onscreen which is not in the books that she said, 'I wish I thought of that' was a thing that Alfonso Cuaron had on the third Potter film." he says of The Prisoner of Azkaban.
And that was?
"To make the temperature drop when the Dementors came by so that you would see the water freeze over," he says. "That's the only thing that she's gone, 'Oh, God. I wish I thought of that.' "