Through the relationship between the old man, Santiago, and the boy, Manolin, in The Old Man and the Sea, Hemingway conveys to the reader the message that real friendship is about faith, companionship, and emotional support.
When Manolin is with Santiago, Santiago feels more hopeful and more confident than when he is alone. Indeed, Hemingway writes that Santiago's "hope and confidence... freshen[s]" in the company of the boy "as when the breeze rises." Santiago's hope and confidence rises when Manolin is around because of the emotional support that Manolin offers him. Manolin reassures the old man, for example, that he will "not fish without eating while [he is] alive."
Manolin also offers the old man companionship. The old man is lonely and misses his wife, and he would have no companionship if not for the boy. On the wall of the old man's shack, there once was a photograph of his wife, but he took this down, "because it made him too lonely to see it." The boy is aware of the old man's loneliness and offers his companionship as a remedy for this loneliness.
Early in the story, the old man and the boy recall a time when the old man "went eighty-seven days without [catching any] fish." During this period, the boy left the old man's side because his father told him to, and the boy had to obey his father. The old man and the boy remark that the boy's father "hasn't much faith," but they agree that they do. The old man tells the boy, "I know you did not leave me because you doubted." The faith that the old man and the boy have in one another helps to sustain the old man's spirits when he is at sea. For example, later in the story, when the old man is struggling to catch the marlin, he says to himself, "I told the boy I was a strange old man... Now is when I must prove it." The implication here is that the old man is driven to succeed and endure so as to justify the faith that the boy has in him.