John Steinbeck understood and liked people, but he was not sentimental about them. In Of Mice and Men he shows that most of the characters, like human beings in general, have good and bad, kind and cruel, generous and selfish sides to their natures. Candy is not an exception, but he has to keep his darker side hidden because he is old and weak. He can’t afford to antagonize anyone. He is holding on to his precarious position at the ranch in constant fear of being cast out into the cold, cruel world, with no hope of finding another job.
Here is Steinbeck’s description of Curley’s wife as she lays dead on the floor of the barn:
Curley’s wife lay with a half-covering of yellow hay. And the meanness and the plannings and the discontent and the ache for attention were all gone from her face. She was very pretty and simple, and her face was sweet and young. Now her rouged cheeks and her reddened lips made her seem alive and sleeping very lightly. The curls, tiny little sausages, were spread on the hay behind her head, and her lips were parted.
And here is what Candy says to the dead girl when he is alone with her:
“You God damn tramp,” he said viciously. “You done it, di’n’t you? I s’pose you’re glad. Ever’body knowed you’d mess things up. You wasn’t no good. You ain’t no good now, you lousy tart.”
Steinbeck had already shown that nearly every character in his story had a cruel side. George protected and cared for Lennie, but he also abused him verbally on many occasions. Lennie loved little animals, but he deliberately killed them. The boss who interviewed George and Lennie when they arrived was a just and hard-working man but also a bully. Curley had a vicious streak he didn’t even try to hide; instead it was his his vulnerable side he tried to keep hidden. Poor lonely Crooks is an object of pity, but he takes sadistic pleasure in torturing Lennie when they are alone by suggesting that George has probably abandoned him and may never come back. Curley’s wife is sexy and seductive, but this simple girl shows a shocking mean streak when she suggests to Crooks that she could easily have him lynched just by telling the white men that he had molested her. Carlson shows his mean streak when he gets all the men to pressure Candy into allowing him to kill his dog.
Candy does not show the dark side to his nature until he curses the dead girl in the barn. Steinbeck must have invented this dialogue for the specific purpose of showing that Candy was like all the others (with the possible exception of Slim) in having a cruel streak to his nature. Candy is only thinking about himself and his own loss. He cares nothing about the girl. He can’t see that her face is “sweet and young” or that “the meanness and the plannings and the discontent and the ache for attention were all gone from her face.” This ugly side of Candy’s nature had to be shown somewhere in order to make him seem like a real person rather than just a quaint, stereotypical character.
Steinbeck was one of the most popular writers of his day, and he remains popular with discriminating readers because of his honest, realistic depiction of men and women. His fiction evokes many strong feelings, but he is never maudlin or romantic. He was always a realist, and his characters are always realistic in their being human and thus being mixtures of good and bad, kind and cruel, generous and selfish, strong and weak, honest and dishonest, like the rest of us. Ernest Hemingway once said, “"The most essential gift for a good writer is a built-in, fool-proof, shit detector." Steinbeck was a good writer.
Candy is upset about the death of Curley’s wife because he thinks it’s the end of his dream to own a ranch with George and Lennie.
Candy is an old swamper on the ranch that George and Lennie work on. He is a lonely man who has no one but his old stinky dog until the men decide to shoot it and put it out of its misery. When George and Lennie tell him about their dream of owning a ranch, he takes it on as his own. Candy gets so caught up in the dream of the ranch that he focuses all of his time and energy on it. According to Crooks, he “just sets in the bunkhouse sharpening his pencil and sharpening and figuring" (Ch. 4). He does calculations about the ranch to keep himself distracted and occupy his mind.
Lennie, the gentle giant who does not know his own strength, likes to pet soft things. He wants to pet Curley’s wife one day in the barn, along with the puppy he “petted” accidentally to death. When he walks in and finds Curley’s wife dead, he sees that dream threatened. He knows soon enough what happened.
But Candy said excitedly, "We oughta let 'im get away. You don't know that Curley. Curley gon'ta wanta get 'im lynched. Curley'll get 'im killed." (Ch. 5)
Candy knows that Lennie killed Curley’s wife. He also knows that Curley will come after Lennie with all he’s got. He knows that George and Lennie will have to go on the run, at the very least. Their dream is going up in smoke.
Of course, Candy is right. George and Lennie’s dream, which Candy borrowed, can never come to pass. It was never anything more than a dream, and Candy never more than borrowed it.
Once Candy learns that Lennie killed Curley's wife, he is upset. He is saddened because he knows Lenny's fate is set, that he will be killed. If Lenny is dead, that means George will no longer go to the farm, which means that he will not live the farm dream as well. This is something he looked forward to, and is upset because he will live the rest of his days on this farm where he currently lives. His little glimmer of happiness is gone, because Lennie killed Curley's wife.