Why did George at one time play jokes on lennie?why did he stop?what do we learn about the interdependence of George and lennie

George told Lennie to jump into the river even though he knew that Lennie could not swim. Lennie does jump but nearly drowns. Lennie is so grateful for being saved that forgets that George had told him to jump in the first place. Consequently, George decided to stop playing jokes on Lennie. We get the sense that Lennie means more to George than someone to play pranks on: he feels guilty for causing Lennie pain.