Each time Curley's wife is mentioned or introduced to the reader, we learn more about her. She starts off as reasonably one-dimensional, but the more we encounter her, the more we gain insight into her character. It is therefore ironic that, even though we do not know her name, she displays more character than most of the others in the novel. Further irony lies in the fact that it is this nameless character's brief interlude with Lennie which leads to the novel's tragic denouement.
She is first mentioned by the swamper (Candy) who mentions that Curley had just recently married her, adding some lewd remark about Curley's actions regarding her. He further mentions:
“Well—she got the eye.”
“Yeah? Married two weeks and got the eye? Maybe that’s why Curley’s pants is full of ants.”
“I seen her give Slim the eye".
He clearly suggests that Curley's wife is a flirt and that he is aware of it, which makes Curley quite jumpy.
When Curley's wife first makes an appearance, the author's description of her makes it clear that she wanted to be noticed. She is all made up and dressed in clothes which would be incongruous in a rural setting:
Both men glanced up, for the rectangle of sunshine in the doorway was cut off. A girl was standing there looking in. She had full, rouged lips and widespaced eyes, heavily made up. Her fingernails were red. Her hair hung in little rolled clusters, like sausages. She wore a cotton house dress and red mules, on the insteps of which were little bouquets of red ostrich feathers. “I’m lookin’ for Curley,” she said. Her voice had a nasal, brittle quality.
It is also clear that she fears her husband for, as soon as Slim tells her that he had gone into the house when she enquires whether Slim had seen him, she quickly disappears.
"... I seen him goin’ in your house.”
She was suddenly apprehensive. “’Bye, boys,” she called into the bunk house, and she hurried away.
George thinks she's a tramp and a rattrap whilst Lennie comments on her beauty - a comment which makes George scold him and warn him about keeping away from her. To emphasize the point, George later questions Lennie about his visit to the barn and asks him if he had seen "that girl." He states that such girls are jailbait and reminds Lennie of what had happened to an associate of theirs (Andy Cushman) because of such a woman.
We learn quite a bit about Curley's wife when she addresses Lennie, Candy and Crooks in the harness room where Crooks has his bunk. She comes around and asks about the men who had all left for town. It is clear that she is lonely and frustrated and needs company. She displays an understanding of the men's dilemma for not wanting to have anything to do with her and her remarks make clear her insight:
“Funny thing,” she said. “If I catch any one man, and he’s alone, I get along fine with him. But just let two of the guys get together an’ you won’t talk. Jus’ nothing but mad.” She dropped her fingers and put her hands on her hips. “You’re all scared of each other, that’s what. Ever’ one of you’s scared the rest is goin’ to get something on you.”
“Well, I ain’t giving you no trouble. Think I don’t like to talk to somebody ever’ once in a while? Think I like to stick in that house alla time?”
It is also clear that she has dreams and thinks of having a better life without Curley.
Think I’m gonna stay in that two-by-four house and listen how Curley’s gonna lead with his left twicet, and then bring in the ol’ right cross?
What becomes apparent mostly is that she has dreams and she confides in the three men telling them about how she could have become famous and be in pictures. She is somewhat miffed that she is in her current situation and has to keep company with what she feels is a bunch of losers.
Furthermore, it is obvious that she has 'street smarts', since she easily figures out that it was Lennie who had broken Curley's hand even though the men do not divulge any information. She also has a nasty streak to her and uses racist tones when she addresses Crooks, threatening him:
“Listen, Nigger,” she said. “You know what I can do to you if you open your trap?”
... She closed on him. “You know what I could do?”
Crooks seemed to grow smaller, and he pressed himself against the wall.
“Well, you keep your place then, Nigger. I could get you strung upon a tree so easy it ain’t even funny.”
Curley's wife knows more about the fears and concerns of the men on the farm than they would like her to. She has no qualms in using her knowledge to manipulate them. There is much pathos in her unfortunate situation and, sadly, it is her desperate need for some appreciation and attention that results in a most tragic epilogue.