"Well, s'pose, jus' s'pose he don't come back. What'll you do then?"
Lennie's face wrinkled with apprehension. "I don' know. Say, what you doin' anyways?" he cried. "This ain't true. George ain't got hurt."
Crooks bored in on him. "Want me ta tell ya what'll happen? They'll take ya to the booby hatch. They'll tie ya up with a collar, like a dog."
While Lennie and Crooks are talking in Crooks' bunk, Crooks begins to tease Lennie about the possibility of something bad happening to George. What major theme in the novel is being developed here?