Of Mice and Men by John Steinbeck traces the unrealistic expectations of George and Lennie as they try to better themselves and strive for a dream where "guys like us" can live on their own land unlike most migrant workers because, as Lennie says, "I got you... and you got me..." George berates the fact that they are considered to be without family or ties because they move from job to job. Accordingly, one of the main themes is loneliness and isolation and feelings of never being good enough, and as such alienated from society.
Curley's wife is the only woman on the ranch and therefore she promotes this theme of alienation. It is significant that she isn't even named in the story and the men show no respect for this woman who Candy describes as "a tart." Her feelings of isolation are also apparent through her attention-seeking behavior and lead to the ultimate tragedy when Lennie kills her accidentally. He is the only one to show genuine kindness to her and her character reveals how improbable George and Lennie's dream is. Therefore, she also contributes to the theme of reality versus idealism because George and Lennie's dream will be shattered because she only considers her own needs and fails to even care how susceptible Lennie is as long as she has "someone to talk to." Furthermore, when George makes the decision to kill Lennie in an attempt to save him from Curley and the mob and the presumed consequences, it can be said that Curley's wife then also assists in furthering the theme of friendship. She has no friends but George feels that he has no choices in what he must do for his friend. Although Curley's wife is already dead, it is her actions and Lennie's reactions which have created this devastating scenario in George's ultimate test of loyalty.
Candy has his own issues and his life has been a series of disappointments and unfortunate occurrences. His life is one futile moment after the other. When George and Lennie arrive, their dream signifies hope for him and a possible future so that his character supports the theme of idealism versus reality. He is desperate and offers his life savings. He clings to this idea because he has suffered greatly and has been dis-empowered and alienated, made worse by his disability. He feels powerless and has such a negative perception of Curley's wife although, ironically both characters support the same themes. He is desperate to find more meaning in his life and recognizes the special bond between George and Lennie. He understands George's decision to end Lennie's life and shows his support. He has unwittingly become George's only friend.