At the beginning of the novel, the narrator introduces his story as a puppet show put on in the Vanity Fair. One by one, the narrator examines the main characters' puppets—which foreshadow, metaphorically, key qualities of the characters' personalities that will come through over the course of the novel: "The famous little Becky Puppet has been pronounced to be uncommonly flexible in the joints, and lively on the wire," the narrator notes, while "the Amelia Doll, though it has had a smaller circle of admirers, has yet been carved and dressed with the greatest care by the artist." And, finally, "the Dobbin Figure, though apparently clumsy, [...] dances in a very amusing and natural manner."
The Becky Puppet's physical flexibility and animated behavior anticipates Becky's own moral flexibility—her ability to play many different parts, to manipulate her way up the social ladder, and to work all sides of a situation. The Amelia Doll's precious, lovely appearance anticipates her position in the novel as a particularly lovely, virtuous character who elicits sympathy from the reader—and the narrator's note that the artist has crafted Amelia Doll "with the greatest care" predicts the narrator's own unabashed affection for Amelia herself. The Dobbin Figure, meanwhile, is clumsy but natural—not unlike Dobbin's genuine, honest demeanor and notable lack of social tact.
It's no coincidence that the narrator would prime the reader for his story by focusing on the physical appearance and mannerisms of each character's doll. In the England that Thackeray portrays in Vanity Fair (a satirical version of England in the early 19th century), appearance is everything: the vanity of the upper classes feeds the interminable gossip and moral judgements that, in turn, establishes the English social hierarchy. Though Thackeray shows the reader the complexity and humanity of each character, the characters themselves often refuse to see each other in the same nuanced light.
In Chapter 17, Thackeray reflects on an unusual feature of the European upper class—amongst the wealthiest members of society gather a number of pretenders, who manage to live the lifestyle of nobility without any of the money. His observations foreshadow the collapse of the Crawley family:
We see Jack Thriftless prancing in the park, or darting in his brougham down Pall Mall: we eat his dinners served on his miraculous plate. ‘How did this begin,’ we say, ‘or where will it end?’ ‘My dear fellow,’ I heard Jack say once, ‘I owe money in every capital in Europe.’ The end must come some day, but in the meantime Jack thrives as much as ever; people are glad enough to shake him by the hand, ignore the little dark stories that are whispered every now and then against him, and pronounce him a good-natured, jovial, reckless fellow.
Every once in a while, Thackeray throws into his narrative a reflection on society with the help of proverbial characters standing in for the real characters of his story. "Jack Thriftless," needless to say, is not a real person but a personification of the human capacity for greed beyond measure.
In any case, Thackeray's reflection clearly foreshadows Rawdon and Becky Crawley's predicament much later in the novel: infatuated with the high life and perpetually incapable of securing an inheritance of her own, Becky creates an identical situation to the one described above and takes on debt after debt in order to sustain the high life. Eventually, Becky's greed will land Rawdon in debtor's prison.
In Chapter 51, Becky hosts a game of charades at Lord Steyne's residence with an ancient Greek theme, complete with abridged versions of Greek drama that the participants put on between charade guesses. In one such interlude, Thackeray uses an allusion to Aeschylus's tragic play Oresteia as a source of sinister foreshadowing:
A tremor ran through the room. ‘Good God!’ somebody said, ‘it’s Mrs Rawdon Crawley.’ Scornfully she snatches the dagger out of Ægisthus’s hand, and advantances to the bed. You see it shining over her head in the glimmer of the lamp, and – and the lamp goes out with a groan, and all is dark.
In this truncated version of Oresteia, Becky plays the part of Clytemnestra—a figure from Greek mythology who falls in love with Aegisthus while her husband, the legendary Greek king Agamemnon, is away to fight the Trojan War. To be with Aegisthus, and to avenge her daughter, Iphigenia, whom Agamemnon sacrifices in the war effort, Clytemnestra ultimately kills her husband.
By casting Becky as Clytemnestra in this sequence, Thackeray not-so-subtly hints at the disastrous events of the next few chapters. Like Clytemnestra, Becky will cause the death of her husband as a result of an illicit affair: through her seductive manipulation of Lord Steyne, Becky secures Rawdon, her husband, a government post in a far-off colony—where he promptly dies of disease.
As could be expected, given this context, Becky plays the part of Clytemnestra with aplomb:
Rebecca performed her part so well, and with such ghastly truth, that the spectators were all dumb, until, with a burst, all the lamps of the hall blazed out again, when everybody began to shout applause. ‘Brava! brava!’ old Steyne’s strident voice was heard roaring over all the rest. ‘By —, she’d do it too,’ he said between his teeth. The performers were called by the whole house, which sounded with cries of ‘Manager! Clytemnestra!’
The "ghastly truth" of Becky's performance is more real than the audience can suspect: Becky barely has to act to play her role, and merely taps into her sinister nature that she has, thus far, managed to hide from English society. She cannot keep up appearances indefinitely, however—while Steyne's effusive praise for Becky makes sense in the context of her performance, he won't be able to mask his impropriety for much longer.
Clytemnestra's is an archetypal example of female power in Greek literature—in the face of an impossibly cruel world, she takes her life into her own hands and escapes the restrictions of her identity as Agamemnon's wife. Likewise, although Becky's manipulation causes no shortage of harm over the course of Vanity Fair, it is also the source of her agency—her ability to rise above the restrictions of her gender role in 19th-century England.