How did Phineas change in A Separate Peace?

Phineas, also known as Finny, changed in "A Separate Peace" by John Knowles by becoming more aware of the darker aspects of human nature, including his own vulnerabilities and the realities of the war looming over them. He transformed from a carefree, charismatic figure to a more introspective and introspective individual as he grAppled with the complexities of the world around him. Ultimately, his experiences led him to a deeper understanding of himself and the nature of friendship.