How does its (friendship) presence or absence affect different characters, in their actions and in their relationships? What does it require of people, and what does it offer them in return?

Of mice and men by John Steinback

Analyze how Steinbeck portray friendship in Of Mice and Men. For example, look at the complex relationship between George and Lennie as well as other character relationships in the novel. What keeps them together, the difficulties they each have, and how are they different from the others in the farm (Specifically George and Lennie). How does its (friendship) presence or absence affect different characters, in their actions and in their relationships? What does it require of people, and what does it offer them in return?