Crooks wants company and Curley wants to be important.
Crooks and Curley do have something in common with George and Lennie. All are marginalized in different ways. On the ranch, it is easy to see how egos can be bruised with so many men living in close quarters. As with most people on the fringes of society or a group, the ranch hands want something more from their lives.
Crooks wants to be useful, because he is crippled, and accepted, because he’s black. He lives a lonely life.
Crooks works hard, even though he has a bent back.
“You told me to warm up tar for that mule’s foot. I got it warm.”
“Oh! Sure, Crooks. I’ll come right out an’ put it on.”
“I can do it if you want, Mr. Slim.”
“No. I’ll come do it myself.” He stood up. (chapter 3)
Crooks lives a fairly isolated life, because of his color.
I ain’t wanted in the bunk house, and you ain’t wanted in my room.”
“Why ain’t you wanted?” Lennie asked.
“’Cause I’m black. They play cards in there, but I can’t play because I’m black. They say I stink. Well, I tell you, you all of you stink to me.” (ch 3)
Crooks feels underappreciated. As he tells Lennie, “If I say something, why it’s just a nigger sayin’ it.” (ch 3) He tells Lennie how lonely he is:
“A guy needs somebody—to be near him.” He whined, “A guy goes nuts if he ain’t got nobody. Don’t make no difference who the guy is, long’s he’s with you. I tell ya,” he cried, “I tell ya a guy gets too lonely an’ he gets sick.” (ch 3)
Curley wants to be important. He almost picks a fight with Lennie from the start, because he seens Lennie is big. When George asks about him, he finds out the Curley used to be a boxer.
“That’s the boss’s son,” he said quietly. “Curley’s pretty handy. He done quite a bit in the ring. He’s a lightweight, and he’s handy.” (ch 2)
As a boxer, Curley would have been important. On the ranch, he is mostly just one of the hands. He does not feel respected (note that he tells George and Lennie to speak only when they’re spoken to). His wife flirts and he picks fights. Curley clearly feels no sense of control, and he desperately wants it.