As drifters in "Of Mice and Men,' the workers have had to leave their homes during the Depression era; thus, they belong no where and to no one. Even Curley, who is married, does not belong to his wife who, in her alienation, seeks to "talk" with the other men.
With this alienation and disenfranchisement, the ranch workers are suspicious of one another. Already isolated by his differing race, Crooks is crulelly forced to live in the barn and is, thus, totally isolated from the others. He says, "A guy goes nuts if he ain't got nobody." The old man, Candy, is soon to be rejected as he knows he is almost too old to be useful; his old dog's death by the callous and insensitive Carlson is symbolic of the inhuman punsihment Candy will soon receive.
While at their weakest, isolated and nearly destitute, the men still seek to oppress others. In fact, Steinbeck conveys the idea that the strength to oppress others it itself born of weakness. In their powerlessness, they seek some type of gratification, so the men antagonize Lennie especially because he is unaware of the predatory powers around him.
The character who personifies this cruelty out of weakness is Curley, who is ready to fight at a momen'ts notice. Jealous of his wife, Curley is antagonistic to all the men and, knowing that Lennie is mentally disabled, Curley attacks him, against Slim with his "God-like eyes" Curley backs down. Of course, the final act in which George kills Lennie shows that even George's love cannot protect against the wolfish nature of man.