what is slim's role at the end of the story?

Slim immediately interprets the scene accurately. Carlton and Curley, however, assume that George wrestled the Luger away from Lennie before shooting him. George, speaking in a whisper, affirms their false version of the events. The novel closes as Slim reassures George that he "had to do it," while Carlson and Curley look on in confusion, wondering why they are so upset. Slim is very much a wise councillor in this story. He is able to mediate between the bond of George and Lennie and the harsh realities of the world.