His clothes, his hair, his house, his eating, his drinking, his affairs, his paunch — just so, telling all about his life in that slight bulge, standing out from the rest of his well-exercised body — mark him out as a man who is ready to go under, but for a mission.
That he finds with Lucas.
American Gangster has been nominated for two Oscars, for art direction and for acting. It's reflective of the strength of the film's performances that the nod for acting has gone to another character, Lucas's mother, played by Ruby Dee. She has few speaking moments in the film, but she brings everything that Lucas represents onto the screen every time she appears.
And everything that she has gone through — in the hovels of North Carolina — in one reflexive slap on Lucas's cheek.