It's no secret that John and Norton are enemies. "Lorraine told you she thinks Norton and I hate each other. It's true," (90). Although John may drink and smoke, he's a good person at heart. Norton is not.
Norton's nickname is "The Marshmallow Kid," because he was caught stealing marshmallows as a kid. Not much has changed. He is an opportunist; always looking to benefit himself, regardless of who's in danger of being hurt because of it. So when Norton realizes that John and Lorraine are spending time with Mr. Pignati, he decides he wants in on the "action."
However, John is wary of all things Norton. "Now you can understand why I was suspicious when Norton invited me to the cemetery to have a beer just before Thanksgiving," (91). His suspicions prove to be logical, because Norton wants to know what's going on with the Pigman.
At first, Norton suggests that it might be something unsavory, "Is he queer or something?" (91). But then he gets to the point of his interrogation, "Has he got anything worth stealing?" (91). John tells him he doesn't, and tries to end the conversation, but Norton persists. He calls Lorraine a screech owl, which angers John, and leads him to insult Norton in return. As tempers flare, Norton makes the worst threat imaginable.
"If you don't give me a little more information about that old goat, maybe Dennis and me will pay a little visit over there ourselves," (93). John pretends he's not bothered by this warning; however, it leads him to realize how much he really cares about Mr. Pignati.
John loves spending time with Mr. Pignati. He appreciates that Mr. Pignati allows him to be himself, and he doesn't want Mr. Pignati being taken advantage of, robbed, or worse, hurt. He respects him as a person and as a friend. For this reason, John will not tolerate Norton's ultimatum. The final sentence of chapter 9 proves this: "That was the Pigman, and I knew I'd kill Norton if he tried to hurt the old man," (95).