Charlie starts as an intellectually challenged adult with a naive and innocent view of the world, eager to learn and be accepted. After undergoing surgery that significantly increases his intelligence, he initially experiences joy and success, gaining new insights and social status. However, as his intelligence grows, he becomes increasingly isolated, alienated from others, and aware of the harsh realities of life, including the complexities of relationships and human emotions.
Ultimately, Charlie’s intelligence deteriorates back to its original state, and he regresses to his initial innocence, albeit with a deeper understanding of pain and loneliness. This cyclical journey illustrates how his character development reflects the theme of human connection and the fragility of intelligence, bringing the plot full circle as he returns to a simpler state, albeit with a poignant awareness of what he has lost.