Who is Overseas Chinese Lu from Death of a Red Heroine and what is their importance?

Lu is an old friend of Chen. They are very different, but have remained friends despite their differences. Chen loans Lu money to open a restaurant. Lu uses his connections to help Chen wherever he can. He involves himself in Chen's personal life and takes pride in being more Westernized, though this brands him an outcast of sorts. He provides a safety net of sorts for Chen when Chen is considering quitting the police force. Chen's interest in Lu's restaurant gives Chen a job to fall back on if he finds his life and career in ruins. Chen is exuberant and outgoing, mostly free of the constraints that trouble the other characters. He provides a good contrast to the other characters.