What is the mood in Of Mice and Men?

""I never seen a guy really do it. If you guys want, I'd come an' lend a hand."" Crooks' view changes the reader's opinion because of his experience at the ranch (pg. 76)Lenny breaks curlys wifes neck. Witch makes you lose sympathy for him "don't you go yellin'," he said, and he shook her; and her body flopped like a fish. And then was still, for Lennie had broken her neck. (Pg. 91)