Claudette is the head of a drug syndicate. Everyone except for Johnny and Denny are aware and/or involved in this. Lisa is in a relationship with Johnny so that she can use his connections at the bank to launder money. She was forced into the relationship by Claudette, who values the success of her business over her daughter’s well-being, which is why Lisa doesn’t just leave Johnny nor does Claudette get upset when she’s told that Johnny hit her.
The phrase “breast cancer” is actually code for an informant close to the heart of the operation and Claudette is worried that the house is bugged. This fear is later given weight by the tape recorder Johnny uses to spy on Lisa. The informant is, in fact, Peter. The syndicate members start to suspect him, as evidenced by Mark holding him over the edge of a building. In Peter’s final scene, they all change into tuxedos. This is because Mark wants to make sure he is not wearing a wire. When Peter is driven off by the taunting, Mark follows and kills him.
The scene with the drug dealer on the roof is especially important because this isn’t one of Claudette’s dealers. Claudette and Lisa are worried that someone is trying to make a move on their turf by coming after someone close to them. Despite Johnny’s wishes, Mark convinces him not to call the police and takes care of it himself.
Mike and Michelle (the couple that have the chocolate and blowjob scene early on) are near the top of the organization. They are responsible for collecting the money from everyone beneath them, and pop in to Lisa’s house sporadically to drop it off. Mark is the enforcer, and Lisa is heir to the top position. This is why Mark is able to meet Lisa and Johnny at any time of the day. It is also why they never have to pay at the café, which is just a front for their illicit business.
The photograph of the spoon and overall lack of personal effects in Johnny and Lisa’s house is due to Lisa’s inability to settle down in one spot. She was raised in a volatile and violent environment in which she would have to move at a moment’s notice and leave everything behind. Her inability to maintain a sense of normalcy includes her relationship with Johnny, whom she doesn’t love and is being forced by her mother to stay with. She starts sleeping with Mark to take control of her own life and hopes that Johnny will find out and leave her.
Mark’s feelings towards Lisa are more complex. He has legitimately come to like Johnny, but he doesn’t want to upset Lisa because he is afraid of Claudette. He does eventually develop feelings for Lisa, if only because of her position of power within the syndicate.
At the party, the character Steven is introduced. After Peter was killed, Johnny’s tape recorder was discovered, leading Claudette to believe that there was another traitor. Steven’s job was to find out who in the syndicate could be trusted.When Lisa sees that Johnny was the one tapping the phone and he was just trying to see if she was cheating on him, she realizes that she can use this to make Claudette get rid of him. She calls Mark, partly because she wants to see him, partly to spite Johnny. This sends Johnny into a rage, ending with his suicide. At finding his body, Mark flees before the police arrive. While Lisa will always be bent to her mother’s will, she is at least free of the relationship she was forced into.