Brett's Gender-fluid qualities in The Sun Also Rises

In The Sun Also Rises, we are often reminded of the confusing relationship between Brett and Jake. We see that they love each other "'Don't you love me?' 'Love you? I simply turn all to jelly when you touch me.'" but because of Jake's injury it won't ever work out between them. We also see that Jake desperately attempts to get over Brett numerous times in the novel. "'Were you ever in love with her?' 'Sure.' 'For how long.' 'Off and on for a hell of a long time.' 'Oh hell! I'm Sorry fella.' 'It's all right,' I said. 'I don't give a damn anymore.'" But, the book never discussed the initial spark between Brett and Jake. We know that they met in the hospital where Jake was treated for his injury. And there is where their love for each other blossomed. What attracted Jake to Brett?

I believe that the constant struggle with gender between the two characters may have been what sparked their love. Throughout the book Jake is constantly attempting to assure his masculinity. Because his injury in the war, he is struggling to find his manhood. In some ways that affects his gender, in turn,  makes him want to feel more secure as a man. This I believe is where his relationship with Brett may come from. She is a woman, and Jake is no doubt aware of her feminine qualities. "She was built with curves like the hull of a racing yacht, and you missed none of it with that wool jersey." But, Brett is also a character who likes to play with her gender identity. A lot of the characteristics in Brett's appearance could be considered androgynous. Specifically her short hair cut, but also the things she wears. "She pulled her men's felt hat down and started for the bar." Additionally, Brett acts in a certain way that (20th century) society would not consider appropriate for a woman. One example is her relationship with many, and it seems mostly, men. Also her affection towards drinking. 

Because of Jake's want for masculinity, I believe that Brett's masculine qualities appeal to him.  I also think her confidence in her gender is also probably reassuring to Jake about his identity. Though the book may never mention these ideas, I do think they are worthwhile to explore.