"I'm a police officer."
In the silent office, Heath Ledger murmured to himself, occasionally jotting something down in his notebook. He was dissecting the character "Chan Wing Yan (Billy)." Because specific details like the character's background and the duration of his undercover work hadn't been confirmed yet—he hadn't even known what the name would be—Wang Yang said, "Do you like any name? It doesn't really matter. Alright, alright, Billy it is!" Billy has the connotation of a "police baton" in American English, thus subtly hinting that "Billy" is actually a cop.
Therefore, Heath could only intuitively grasp some of the character's mental states from different periods, sufficient for him to infer certain personality traits, habits, and likes, thus creating his own "Billy."
