The overall mood of the novella is tense and somber. Though there are moments of peace and happiness throughout Of Mice and Men, they are only brief, punctuated by scenes of hardship and tragedy. George and Lennie work hard to pursue their shared dream, but ultimately, the novel heavily foreshadows the tragedy to come, increasing the sense of tension that characterizes much of the novella. By the story's tragic ending, memories of happier times only intensify the somber atmosphere. The final lines of the novella exemplify this mournful mood:
Slim twitched George’s elbow. “Come on, George. Me an’ you’ll go in an’ get a drink.” George let himself be helped to his feet. “Yeah, a drink.” Slim said, “You hadda, George. I swear you hadda. Come on with me.” He led George into the entrance of the trail and up toward the highway. Curley and Carlson looked after them. And Carlson said, “Now what the hell ya suppose is eatin’ them two guys?”
After shooting his long-time companion Lennie in order to spare him from a more violent death at the hands of the mob, George falls silent, overwhelmed with feeling. Only the emotionally perceptive Slim understands George’s grief and attempts to console him, insisting that he “hadda” do it. Curley and Carlson, who are less sensitive and fail to understand the complexity of George’s relationship to Lennie, provide the final lines of the novella. Their somewhat superficial and shallow comments offer an ironic contrast to George’s deeply-felt personal tragedy.