Carlson is a laborer on the ranch where George and Lennie come to work. His main purpose in the novel is his killing of Candy's dog with a Luger which foreshadows George's killing of Lennie with the same weapon. If Carlson has a "dream" Steinbeck does not mention it in the book. Unlike Candy and Crooks, he is never part of George's and Lennie's dream of a "little piece of land."
Carlson doesn't like Candy's dog because it is old and smells bad. He tells Candy that killing the dog would be merciful. The reader, however, may feel that Carlson is simply mean and lacks the ability to understand how much the dog means to Candy. In chapter three he takes the dog out and shoots him. Later in the chapter, Candy comments to George:
“I ought to of shot that dog myself, George. I shouldn’t ought to of let no stranger shoot my dog.”
The stranger was Carlson and George takes Candy's words to heart as he steals Carlson's Luger after Lennie has accidentally killed Curley's wife. He eventually shoots his friend. As with Candy's dog, Carlson does not understand George's actions toward his friend and, at the end, as George and Slim are leaving the scene, Carlson utters the final lines of the novel:
“Now what the hell ya suppose is eatin’ them two guys?”
Some may say that Carlson is hard hearted or simply ignorant toward the depth of affection which Candy felt for his dog and George for his friend.