Lennie is not blessed with overarching intelligence, so it might be a challenge to find specific quotes that highlight his personality. Rather, I think you can find moments and quotations within it that shows his true sense of character. Any quote about "the rabbits" would be one such element. Lennie's obsession with taking care of the rabbits and "tending" to them on the farm that he and George will eventually own is something that drives him, representing his primary motivation. Additionally, I think that when Lennie asks George to "talk about the farm," another element of Lennie's character is revealed. It is one in which Lennie shows his hopeful nature, his faith in dreams. It is something that emboldens him. Lennie's character is rooted in the hope of the future, that he and George will eventually fulfill their shared dream of this farm. I think that Lennie's character is also one where fear of doing the wrong thing is evident. During the confrontation with Curley, Lennie frequently says, "George.." in a sad and uncertain tone. This reflects how Lennie needs George's guidance and does not want to anger him. The fact that he is being beaten by Curley and still calls out to George reflects this. In his discussion with Crooks, Lennie's insistence of finding out where George is and if Crooks has done anything with him when the old stable- hand starts to torment Lennie with George's disappearance is another moment where Lennie's fundamental fear of being without George is evident. These moments are ones where Lennie's character is revealed not through some elaborate quote, but in moments where Lennie's speech becomes a prism through which his own sense of character is revealed.