After being abandoned by his aunt, Lennie became the responsibility of George, who's always trying to protect Lennie no matter what. We think this benefits both of them because neither of them has a family member or someone else to look out for each other.
Curley's wife was looking at men other than her husband for physical affirmation and satisfaction. And there's no doubt she would leave him for someone better (both financially and physically) if every other laborer wasn't afraid of her, being Curley's, son of the boss, wife.
Candy, the old handyman, aging and left with only one hand as the result of an accident, worries that the boss will soon declare him useless and demand that he leave the ranch. Candy’s dog, once an impressive sheepherder but now toothless, foul-smelling, and brittle with age- support Candy’s fears. Past accomplishments and current emotional ties matter little, as Carson makes clear when he insists that Candy let him put the dog out of its misery. Candy’s dog serves as a harsh reminder of the fate that awaits anyone who outlives his usefulness.