The idea of social order in the novel, in general, seems important to the question of Brett's social role or gender identity.
These ex-pats, with new types of people moving in to the upper-strata, are a jumble of diverse backgrounds and probably of diverse futures.
Brett, maybe, can be seen as a person who is caught up in the tangle of change, tempted to participate in the old social order (where old money is the only kind that counts), tempted to participate in the new social order (where nihilism is inherent) and tempted to step out entirely (and remake both herself and a young bull fighter into a new Adam and Eve, bent on passion, bent on forming a bubble or a garden in which to live separate from the bluster and chaos of the world).
Certainly, she is not empowered in a 21st century way. Yet so many of the characters in this novel stand on the doorstep of the rest of their lives, and they have no idea what will happen when they go through. It's hard to assign gender and type to such troubled, dynamic people.
And that doesn't even begin to get into the question of love, which is a definite undercurrent in the novel.
Though Hemingway is a frequent target of feminist critics, he subtly questions gender roles in the novel and reflects the larger gender confusion of the 1920s. Jake’s war wound and sexual impotence puts him in a powerless position for much of the novel. The only thing he seems to want is a woman he cannot have—Brett.
Brett herself is androgynous, with “hair brushed back like a boy’s” and “curves like the hull of a racing yacht.” Her carelessness about sex makes her even more desirable to men: she is not controlling and marriage-obsessed like Frances Clyne, and she is not for sale like Georgette. Brett tags around with men (both gay and straight) and likes to be one of the boys, which includes looking for sexual partners in bars. She is uncomfortable with traditional femininity (she believes she would “look a fright” with long hair and doesn’t want to be “one of those bitches who ruins children”) but does not want to be worshipped as a goddess either. She would rather dance in the Pamplona bars than be “an image to dance around” as the men want her to be.
When she becomes involved with Romero, she is humiliated by his wish that she grow her hair long and be “more womanly.” Ultimately, it is Brett’s androgyny that allows her to keep her distance in a world that distrusts human attachment.
It is a bit humorous to think of Jake as a Victorian woman. Especially since I have a soft spot in my heart for Jake. I think he is so strong and stoic until it comes to Brett. Although, I am not sold on Brett as the "new woman". She is still so dependent on men for her happiness.
Jake is not as blustery as some of Hemingway's hero characters. Or, I have a secret (not really)crush on Jake!
I suppose there might be some of the Victorian, up-on-a-pedestal in Brett. In Ch 4, Jake muses, "This was Brett that I had felt like crying about. Then I thought of her walking up the street and stepping into the car, as I had last seen her, and of course in a little while I felt like hell again. It is awfully easy to be hard-boiled about everything in the daytime, but at night is another thing."
It seems that the woman can soften even the hardest of hearts....perhaps a very Victorian ideal, from which our most masculine of authors was cetainly not immune... Most of Hemingway's men are blustery on the outside, but vulnerable on the inside...think of the Nick Adams stories, for example...