why do you think george tells slim the truth about himself and lennie when he has been cautious and defensive with the others?

Slim is the jerkline skinner at the ranch, Slim is a seemingly ageless man who carries himself with great gravity. He gives Lennie one of his new litter of puppies to care for. Both George and Slim find kindred spirits in each other. Slim is an introspective gentleman. He understands the politics around the farm and the sensitivities that exist between George and Lennie. In turn George finds another guy with similar intellect and sense of life.