Crooks, being a black man in the 1930s was seen as less than Curley's wife. This gave her power and authority over him. Being a woman, she was seen as her husband's property. This is further emphasized by the fact that the character remains nameless. Crooks was the only person he had authority over on the ranch. For this reason he threatens to have him "hanged from a tree". This shows that to have power over someone she is willing to be evil and abandon them