"The best barometer of this darker Harry was the change in how he treats Ron and Hermione," says screenwriter Michael Goldenberg. "I watched the movie a couple of nights ago with an audience, and when he first snaps at Ron, there's an audible reaction, a sort of 'What have you done with our Harry?' feeling."

"It is a much more interior journey than the previous films," Goldenberg says. "Harry is struggling. He's haunted. He's isolated and misunderstood and has a deep longing to connect. He's so emotionally impacted that he's a coiled spring."

The screenwriter recalls a key conversation he had with Rowling before he embarked on adapting her book into a screenplay.

"I remember she said something like, 'A psychologically plausible child would have been institutionalized by now, having gone through all this. He's suffered and tolerated so much.' "

"I started out wanting him to be incredibly angry, then I started to pull back a wee bit," Yates says. "If he got too angry, he wouldn't be very likable or sympathetic, so we trod a fine line to service the notion that someone who's troubled and conflicted and misunderstood has the right to be angry. We tried to present it so you feel for his plight, so the anger is rational."