Jill's ever-evolving relationship with Michael Smith seems to provide the bulk of her character arc. Not that she's not her own person, but… she's not really her own person.
We can basically separate the different stages of Jill and Mike's relationship with regards to the jobs Jill has throughout the novel. Of course, the way Jill is able to take on so many different roles hints that our way is only one of many ways to look at Jill as a character. We hate to admit it, but other people can have valid points, too.
At the beginning of the novel, Jill is a nurse at Bethesda hospital. But she's no ordinary nurse—she's a nurse with convictions. She hears that the Man from Mars can't be visited by women, and so, naturally, she takes that as challenge. She sneaks in to catch a glimpse, but what started as a lark eventually sets Jill's course for the rest of the narrative.
See, Jill instantly takes a liking—a protective liking, actually—to Mike. Ben believes this instinct comes from her being a nurse, that Jill "feel[s] maternal toward [her] charges" (18.7). She certainly feels maternal toward Mike. After Ben Caxton's disappearance and her subsequent rediscovery of Mike, Jill decides to break Mike out of prison. Once out, she takes on the role of mother, caregiver, and protector for Mike. She bathes him, tries to save him from Berquist and Johnson, and carries him all the way to the safety of Jubal's house. It's like The Blind Side meets Saving Private Ryan.
This initial role as Mike's protector eventually lessens as Mike becomes more capable in human society. But once a Mama Bear, always a Mama Bear: this connection never truly disappears, and Jill stays close to Mike for the rest of his life.
Next up, Jill is hired by Jubal to learn the Martian language. While Jill may technically be the student, this phase of her character arc has her playing the role of mentor to young Mike: she teaches him how and why to wear clothes, helps teach him how to cook, and begins informing him about the difference between Martian and human culture.
So, is this a good thing? Jubal certainly doesn't think so:
"Woman, here, by the grace of God and an inside straight, we have a personality untouched by the psychotic taboos of our tribe—and you want to turn him into a copy of every fourth-rate conformist in this frightened land!" (12.11)
But Jill has good intentions, right? What are her intentions exactly? And how do you think she handles the situation?
Maybe most importantly, Jill is Mike's first kiss and possibly his first lover (the name of the partner is left purposefully ambiguous). That means she's the one who teaches him his first lessons in human sexuality, a major tenet of his later teachings at the Church of All Worlds.
As Mike gains more independence, especially after their visit to the Fosterite tabernacle, Jill can't really be his go-to lady anymore. And so, when she and Mike leave to travel the world, we witness the third evolution in her character.
After spending time on the road with Mike, Jill goes from teacher to student. Under Mike's tutelage, Jill begins to learn and assimilate to more Martian ways of thinking.
For example, she throws away more traditional sexual customs. Jill is first introduced as a woman whose "hobby [is] men" (4.1), so we know she's no prude. Yet, when she first learns Duke collects porn, she is disgusted at the idea. After working as a show girl and learning from Mike, her views on female and male sexuality begin to change drastically. With Mike's help, she sees through the eyes of the men in the audience of her peep show, and she comes to the conclusion that voyeurism and exhibitionism are perfectly natural and healthy—"she finally [understands], intellectually, Duke and his pictures" (29.42).
Later, Jill becomes a High Priestess and tries to bring other people, including Ben, into the fold of Mike's culture. Her role at this point becomes synonymous with Mike's. As someone who thinks neither purely human nor purely Martian, she attempts to break down the social and cultural norms of Western civilization. Although Mike may die at the end of the novel, Jill lives on, as a disciple, ready to spread the word.
So, that's our take. Here are a few questions to incite additional discussion and conversation on the one named Jill: