Hi there Erin, I think Santiago initially views the great Marlin as an ideal opponent. Santiago feels that this is a world in which “everything kills everything else in some way.” Both the great fish and Santiago have a relationship. I know that sounds odd but they do. Santiago sees the fish as a worthy opponent but as the struggle wears on, he begins to feel pity for his opponent,
"Then he began to pity the great fish that he had hooked. He is wonderful and strange and who knows how old he is, he thought. Never have I had such a strong fish nor one who acted so strangely." (Chapter 2 pg 91)
AS the hours wear on Santiago grows fonder of his fish but their roles in the struggle do not change,
"Fish," he said, "I love you and respect you very much. But I will kill you dead before this day ends." (Chapter 3 pg 8)
By the end of the struggle Santiago ponders if he might sacrifice himself to the majestic fish. The marlin becomes his brother, his comrade in the eternal struggle,
"How many people will he feed, he thought. But are they worthy to eat him? No, of course not. There is no one worthy of eating him from the manner of his behaviour and his great dignity. I do not understand these things, he thought. But it is good that we do not have to try to kill the sun or the moon or the stars. It is enough to live on the sea and kill our true brothers."
Santiago does slay his great fish but by the end of the novella, it is as if they have joined somehow. Santiago reveres his catch; they become symbols of each other.