Final answer:
McMurphy discovers Chief Bromden's secret through observations and conversations, symbolizing their growing bond and understanding.
Step-by-step explanation:
The main character, McMurphy, discovers Chief Bromden's secret through observations and conversations. At first, McMurphy notices that Chief Bromden pretends to be deaf and mute to avoid interacting with others.
As the story progresses, McMurphy gains Chief Bromden's trust and they have conversations where the Chief reveals his true thoughts and experiences, including his belief that the world is controlled by a machine called the Combine. McMurphy's discovery of Chief Bromden's secret symbolizes the growing bond and understanding between them.