I think that one of the most interesting elements about Jig's characterization is how she uses language to convey elements about her character that can be seen as either sarcastic or reflective of desperation. Either way, there is an undercurrent of Jig saying something that has an alternative motive beneath the words. An example of this might be her repeated claims of how she doesn't "care about" herself. Jig does not literally mean she doesn't care about herself, for the concern of the entire dialogue is the implication of her decision which does impact her being. She does care about herself. Yet, Hemingway's inclusion of this line reflects the sarcasm that enters dialogue when two people in a relationship believe opposite entities about emotional qualities. The sarcasm becomes interwoven with pain, alienation, and a sense of despair. We see this one more time at the end when she talks about a condition that combines their past, present, and potential future in one statement:
"And we could have all this," she said. "And we could have everything and every day we make it more impossible."
The claims of "We could have everything" are statements of sarcasm in the vain hope that the results of the present and future do not have any impact on the past. The careless life, or relatively care-free life led before the pregnancy, can be appropriated again even with the impending life change on the horizon. It is to this end that sarcasm is present, an emotion that carries with it much in way of complexity and intricacy.
A good example of Jig's sarcasm occurs when the American tells her, "You don't have to be afraid. I've known lots of people that have done it."
"So have I," said the girl. "And afterward they were all so happy."
Later he says, "And I know it's perfectly simple."
"Yes, you know it's perfectly simple."
Earlier she says, "They [the hills] look like white elephants."
"i've never seen one," the man drank his beer..
"No, you wouldn't have."
What she means is not that he wouldn't have seen a white elephant but that he wouldn't have seen a hillthat looked like a white elephant because he doesn't have enough imagination to see how a hill could look like a white elephant.
In all three of the above examples, we can detect a note of sarcasm in her voice. Hemingway rarely if ever describes how a character says anything. He only uses "he said" and "she said," and often he doesn't even indicate who is speaking because it isn't necessary. But his dialogue is so good that we can hear the tone in which the character is speaking, as in "No, you wouldn't have." Sarcasm is always a matter of tone, as in "And afterward they were all so happy." The word emphasized in that sentence would be "so."
Jig is angry, hurt, bitter, disillusioned, and her feelings come out as sarcasm.