At the end of the novella, Slim consoles George after George has shot Lennie in the back of the head and tells him, "You hadda, George. I swear you hadda" (Steinbeck, 53). Slim understands that George had to kill his close friend in order to prevent him from experiencing a brutal, painful death. Slim is fully aware that Curley and his lynch mob would have tortured Lennie before killing him, which is why George shooting Lennie in the back of the head was an act of mercy. As the wisest man on the ranch, Slim sympathizes with George, who courageously took his best friend's life. Slim also realizes Curley's vindictive, hostile nature and knows that Lennie would have suffered greatly if Curley would have captured him.

Slim understands that George is experiencing a myriad of emotions and is extremely upset about the recent events that transpired, which he could not have prevented. Even though George did not want to end up killing his best friend, he knew that it was the only way to prevent Lennie from a horrific, painful death. Slim's final words demonstrate his understanding and sympathetic nature as he attempts to comfort George in his time of need. By reassuring George that he had to take Lennie's life, Slim is attempting to help George grieve and forgive himself.