Lennie Small is a migrant worker like George Milton, his friend and travelling companion. Due to his mental disability, Lennie is completely reliant on George. Both share a dream of owning a farm together, a dream that Lennie wholeheartedly believes and wants to tend the rabbits at. He is described as a large, lumbering and childlike character.
This shows that Lennie cannot take care of himself and that George had to be the responsible one and take care of everything for the two of them, holding their work papers, and even their own plates and cutlery. The reason that George kept his head down ad saved his money was so he could achieve the dream of the ranch with Lennie. Otherwise he “could take (his) fifty bucks and go into town.