Gene is a follower through much of the action of the novel, influenced first by Finny then by Brinker. In the end, Gene learns an important lesson about himself and how to live. He realizes that he must stop following the examples of others and make decisions on his own.
Finny, the youthful and innocent athlete, influences Gene to be like him, to turn away from serious matters like scholarship and war. Brinker is the opposite in his influence on Gene, emphasizing accountability and seriousness.
Gene goes back and forth in his preferences for these sets of qualities. His inner life is reflected outwardly as well.
At various times in the novel, he is highly competitive, selfish, insecure, and combative. On other occasions, he is courageous, mature, and dependable.
Years after the action of the story, Gene has learned to accept the idea that a person cannot achieve peace through others, but must work out turmoil internally.
"Gene Forrester comes to learn that his war, the essential war, is fought on the battlefield within. Peace comes only when he faces up to the fact. The only escape, the price of peace, is self-awareness."
Any real peace, then, is achieved "separately" and personally.