Joe's bitter attack against McEachern represents all the hostility that he has felt for years and his youthful desire to protect the woman with whom he has been sleeping, especially when she has just been attacked by McEachern.
Most important in this chapter is Bobbie's sudden betrayal of Joe. She was the first woman to whom Joe freely opened his heart. Joe's youthful love for Bobbie existed on an idealistic plane because he was able to confess his Negro blood to her and be accepted by her as an individual. However, her betrayal of his love, which is accompanied by the taunts of "nigger bastard," implants the idea in his mind that owing to his blood he must remain the isolated being. Thus the episode with the dietitian and the interlude with Bobbie Allen convince Joe that he will never be able to have a trusting relationship with a woman.
Chapter 9 brings to a close all the narration involving Joe's early life. The two main types of influence are extreme rigidity and religious mania as seen in Hines and McEachern as opposed to the loose morality of the dietitian and Bobbie Allen. Joe's conflict is presented in the contrasting manner in which he violently attacks (and perhaps kills) McEachern, and is, in turn, violently beaten up as a result of Bobbie Allen's betrayal.