Curly is he son of the boss on the ranch where George and Lennie work. While he works hard to emit this tough guy persona (there's even rumors around the ranch that at one time he was a champion prize fighter). However, in reality, Curly's just a coward and a bully. While the other men on the ranch put in hard days of labor, he walks around in high heeled boots to show off his status on the ranch. We see his bullying ways when he first meets Lennie. Wanting to be the big man on the ranch, Curly tries to pick a fight with gentle Lennie. Lennie, bigger and stronger, breaks Curly's hand by wrapping his own hand around Curly's. Like a child, Curly wants to run and tell his dad, but the men convince him not to by playing on his prideful nature- if he doesn't tell, they'll let him keep his dignity and say it was caught in a machine.
When Curly's wife is found dead, Curly is quick to lead the mob to find and kill Lennie. While he fears his wife's been flirting with the men on the ranch, he knows he hasn't been able to stop it. He also doesn't show much remorse at his wife's death, but he does jump at the oppurtunity to get his revenge on Lenny.