George and Lennie are on their way to the ranch they are going to work on, and they decide to camp out for the night. In case Lennie gets in trouble, George tell him to remember this place. During their time at the camp, a snake goes by. This suggests that Lennie will give in to temptations and cause harm again. This shows the theme that old habits will not change, as Lennie has gotten in trouble in the past and will continue this.
George explains his and Lennie's relationship. This follows everyone in the bunk wanting to shoot the old dog. George and Lennie are almost like Candy and the dog because they have been together for a long time. In conclusion, this supports the central idea hat disability does not change the amount of care one has for something/someone else.
Curly's wife offers to let Lennie touch her hair, and when he doesn't let go, Lennie kills Curly's wife by accident. Due to this, Lennie will have to go to the campsite to hide because people will be looking for him. This supports the central idea that Lennie causes trouble wherever he goes.
Lennie followed George's directions and went to the campsite. George finds him there and shoots him before anyone else can get there. George shoots him to stop Lennie from suffering even greater because he knows that if they keep running away the same thing will keep happening. With this we can make the conclusion that we have to go through with the most difficult decisions to go on with our lives.