George and Lennie are the main characters in Of Mice and Men by John Steinbeck. George is a small, spare man and Lennie is a strong giant of a man who is also mentally challenged. People who meet the pair for the first time always wonder why George takes care of Lennie (because they can all see that it is rather a full-time job to do so). In chapter three, we hear George explain his relationship with Lennie to Slim.
Though we do not know all the details, we do know that Lennie was raised by his Aunt Clara and George lived in the same neighborhood. When they were little, George did not act as nobly as he does now, and he used to tease and torment Lennie just like everyone else. Despite that, Lennie grew attached to George, and Lennie finally quit taking advantage of Lennie for his own amusement once he discovered that Lennie was so loyal to George that he would literally do anything George told him to do. When Lennie's Aunt Clara died, George took over as Lennie's caretaker.
This childhood friendship has turned into a rare friendship, especially in the world of itinerant ranch hands. George may resent Lennie at times, but the truth is that he needs Lennie as much as Lennie needs him. George says:
“A guy needs somebody―to be near him. A guy goes nuts if he ain't got nobody. Don't make no difference who the guy is, long's he's with you. I tell ya, I tell ya a guy gets too lonely an' he gets sick.”
The fact that George has not always been nice to Lennie makes their relationship even more believable and more satisfying now that they are adults.
George does get some benefit from having Lennie as a companion. George is described as "a little guy," while Lennie is a giant with enormous strength. These two men are struggling to survive in a tough world. Lennie can offer George protection from men who might try to rob him or might pick a fight with him just because he is "a little guy." They have to sleep in boxcars and in hobo jungles. There were twelve million unemployed men during the worst years of the Great Depression. The world was a dangerous place for men who were unemployed and roaming the country looking for work.
James M. Cain wrote a number of good novels about the Great Depression. The best-known of these books is Mildred Pierce. Cain's novel The Moth (1948) contains many chapters portraying the hard lives of hobos traveling all over America in freight cars looking for unskilled temporary laboring jobs.
Just as Lennie has great strength to compensate for his feeble intellect, so George has above average intelligence and "street smarts" to compensate for his small size. The two men have a symbiotic relationship. Lennie needs somebody to tell him what to do, while George can sometimes use a bodyguard.