Our opinion of Jenny Jones change a lot over the course of the novel. In Jenny's case, the reason for the change is only partly because we learn more about her in the final books of Tom Jones. Our sense of Jenny also transforms because she changes so much.
About twenty years pass between the time that we first meet Jenny, a young servant and social outcast in Squire Allworthy's village, and the time that we next encounter "Mrs. Waters," about to be strangled by evil Ensign Northerton. So let's talk about what the heck happens over those twenty years that leads to such changes in Jenny's character and circumstances.
In Book 1, Jenny Jones is a servant in the household of the local schoolmaster, Mr. Partridge. She's not the prettiest girl in the world, but she has something else going for her: "a very uncommon share of understanding" (1.6.8). In other words, she's sharp as a tack. And Jenny isn't just smart; she also works hard to educate herself. At this point, she actually knows a lot more than Mr. Partridge, even though he's the one who is supposed to be in charge of teaching the local kids.
Horribly, though, Jenny's brains actually work against her in this rural village. She's a working-class woman, and all of the other women in her area think that she's getting snobbish and puffed up, with all of her Latin and reading. (Basically, for all of you fans of Disney's Beauty and the Beast out there, think of Gaston's attitude towards women.)The villagers (and especially the women) disapprove of Jenny's cleverness and are jealous of her studies. When the rumor gets out that Jenny is the mother of an illegitimate baby, many of the village women agree that "her learning" (1.6.14) is to blame.
What makes matters worse is that (a) Jenny appears in church one day in a very fine gown from some unknown source (which makes the ladies of the village even more envious), and (b) Mr. Partridge's wife is by nature a deeply suspicious and jealous woman. She looks at Jenny, sees a young woman who spends a lot of time speaking in Latin to her husband, and immediately assumes that the two of them must be exchanging sweet nothings in a language she can't understand. Mrs. Partridge jumps quickly to some nasty conclusions. Thanks to her assumptions and the prejudices of the villagers against young Jenny, everyone agrees that Jenny and Mr. Partridge must be having a secret affair.
Now, when Mrs. Wilkins drags Jenny before Squire Allworthy and accuses her of being Tom's mom, Jenny does say that she's the one who left Tom in the squire's bed. Her confession appears to justify all of the nasty gossip of the villagers, and Squire Allworthy certainly believes that she is Tom's biological parent.
At the same time, even this early on in the novel, we can't help but feel bad for a woman who everybody hates just because she likes to read a little too much. We at Shmoop are super-bookish and nerdy—of course we're going to sympathize with Jenny Jones.
Anyway, Squire Allworthy tries to help out by giving Jenny some money to settle a day's journey away from the village, where her reputation is now mud. But Jenny soon runs away from Somerset entirely, following a man off to who knows where and disappearing from the novel. We don't think too much of her for many hundreds of pages—until we hear her name in Book 18, in fact.
The next time we meet Jenny, we don't know that's who we're meeting. Instead, we encounter a somewhat plain middle-aged woman with "well-formed and extremely white" (9.2.6) breasts. We're not just pointing this out to be sleazy (though we'd like to note that this is Fielding's description). Since Mrs. Waters spends her first three chapters in the book naked to the waist, this description of her bosom keeps getting repeated over and over again. Fielding obviously has his own obsessions.
But because of the raunchiness of the narrator's description—and because Tom and Mrs. Waters quickly fall into bed together—we initially think that the sole reason this character makes it into the novel is for a bit of light-hearted, sexy comic relief. The narrator makes a joke out of her seduction of Tom, comparing it to siege warfare in Book 9, Chapter 5. And once Sophia finds out that Tom has been sleeping with Mrs. Waters, her character appears to be a funny way for the narrator to drive Tom and Sophia apart once again, therefore delaying the plot resolution even further.
It's only when Mrs. Waters jumps back into the plot in Book 18 that we realize that she might have a bigger role in the novel than we had assumed. Because Fielding is extremely careful to lay out exactly how the different characters come together, we know that she hooked up with Mr. Fitzpatrick at the inn at Upton back in Book 9. Nine books later, she is still hanging out with Mr. Fitzpatrick. She's the one who comes to the prison to tell Tom the great news that Mr. Fitzpatrick isn't dead, and that Tom isn't legally responsible for their duel.
Once Mrs. Waters reappears in the book, we realize that she is the unlikely key who is going to unlock the whole novel for us. She is the one who (a) knows Tom's true parentage, and (b) reveals Mr. Dowling's dark schemes to Squire Allworthy. Mrs. Waters arrives at just the right time to resolve many of Squire Allworthy's doubts about his nephew.
There is a sense of almost theatrical closure to Mrs. Waters's sudden appearance at the end of the novel. It's like that famous playwriting rule of Chekhov's gun. Anton Chekhov was a great Russian author who said that you shouldn't introduce a gun into the first act of a play unless it goes off in the next act. In other words, don't include a minor plot point early on unless you are going to follow through with it later in your play.
Jenny Jones is Fielding's version of Chekhov's gun: she disappears in the first act, only to reappear at the end to resolve everything.
Jenny Jones starts out as this woman who is unusual for her learning. She has worked and studied hard, and that's made her life difficult among the judgmental and jealous villagers who surround her.
Then, we find out more of Jenny's back-story as "Mrs. Waters." After leaving Squire Allworthy's estate, she runs away with a man who promises to marry her. They live together (unmarried, but faithful) for twelve years until he dies.
Then, Jenny joins Captain Waters and lives with him as his wife in Bath while conducting affairs on the side. One of these affairs is with Ensign Northerton (which is how she winds up half-strangled, as Northerton runs from the law); another is, as we know, with Tom himself (after he rescues her from Northerton's murder attempt). She hooks up with Mr. Fitzpatrick once they travel together on the same coach from Upton to London. And then, by the end of the novel, we hear that Squire Allworthy has settled a pension on her and she has married the local clergyman, Mr. Supple.
We're glad to hear that Jenny's future is pretty secure by the end of Tom Jones. But we feel kind of sad that there seems to be nothing for her to do with her education, as a working-class woman in this particular time and place. There are no teaching positions or university jobs for lower-class women in Jenny Jones's position.
So in spite of all of her hard work in Book 1, by the end of the novel, Jenny Jones's fate seems tied to the will of the men she has known, including Squire Allworthy and Mr. Supple. We feel like at least part of Jenny's problem in settling down and making a life for herself is that there isn't much of a market for her set of skills. She doesn't fit in comfortably in the social world that Fielding portrays in Tom Jones. Unlike Tom, who can move past his status as an illegitimate child, Jenny's gender seems to be an obstacle to her livelihood that she can't overcome.