George and Lennie speak about their frienship and how this sets them apart from other itinerant workers. While many men working as farm-hands in the era travel from place to place alone, George and Lennie stick together.
Though we might say that George looks after Lennie as a caretaker, it is also true that Lennie serves as a companion for George. Neither man is alone in his travels or in his toil.
We can see this idea explicitly expressed in the first chapter of the novel (and later as well):
Lennie broke in. “But not us! An’ why? Because…because I got you to look after me, and you got me to look after you, and that’s why.”
Lennie's value to George is nowhere clearer than in this passage. Lennie emphatically and clearly quotes something that George has often said. The fact that this is a quote (Lennie quoting George) suggests that George and Lennie feel similarly about the benefits of their friendship.