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.