Lolita at first sight:
[…] without the least warning, a blue sea-wave swelled under my heart and, from a mat in a pool of sun, half-naked, kneeling, turning about on her knees, there was my Riviera love peering at me over dark glasses. (1.10.11)
Humbert immediately regards Lolita as an incarnation of Annabel Leigh, a second chance at lust. Most importantly, the first sight of Lolita is through his eyes, as are all sights of her. We do not know Lolita through any perspective other than Humbert's highly subjective one – thus to talk about Lolita is to talk about Humbert's thoughts about Lolita.
It's important to remember that over the course of the six or so years represented, Lolita changes, but Humbert does not. He is already an adult and is telling the story after it has all happened. The fact that she is a fresh nymphet of twelve-and-a-half at the beginning of the story and a haggard pregnant seventeen at the end matters a lot, especially to Humbert. He keeps close watch of her nymphet quotient – remember you can't be a nymphet after fourteen. As Lolita reaches the ripe old age of fourteen, Humbert notes the changes:
Her complexion was now that of any vulgar untidy highschool girl who applies shared cosmetics with grubby fingers to an unwashed face. (2.14.2)
Lolita is a fantasy, a nymphet, and a figment of Humbert's past, a reincarnation of his lost Annabel, and a girl whose "true nature" as a nymphet, in Humbert's words, "is not human […] but demoniac." Because "Lolita" has become synonymous with tween seductress, the reader is challenged to understand the character beyond the cultural reference – which does not reflect the fact the she is, after all, a victim and not a siren. (In an interview, Nabokov said he was "probably responsible for the odd fact that people do not name their daughters Lolita any more" (source: James Kincaid, "Lolita at Middle Age"). Do ya think?!
Lolita also changes a lot, going from the skinny-armed, freckle-faced, foul-mouthed animated girl (and icon of all nymphets) to a hugely pregnant, jaded married woman just trying to survive. The pop culture abundance and shallowness of her youth becomes a blue-collar struggle against scarcity.
But beyond Humbert's designation as "nymphet," Lolita is an ordinary North American girl-child – real name: Dolores Haze – who loves cheesy pop music, Hollywood melodramas, teeny-bopper magazines, cottage cheese, and bubble gum. She "it was to whom ads were dedicated: the ideal consumer, the subject and object of every foul poster" (2.1.7). At times she is downright boring, bratty, and gross: "There she would be, a typical kid, picking her nose" (2.1.17). Lolita curses and loves slang (words like "revolting," "super," "luscious," "goon," and "drip"), something Humbert is willing to overlook for all his love of fancy talk, Latin references, and multisyllabic words. Despite her casual air and teenage aloofness, Lolita is deeply damaged. Though she makes jokey references to having been "daisy-fresh" (1.32.33) before he defiled her, Lolita and Humbert both know that he has ruined her.
Central to Humbert's defense is that Lolita is already corrupted when he gets to her, no longer a virgin, and therefore, in his mind, fair game. Part of how he sells this image of her is not only by detailing her numerous risqué sexual experiences but also by presenting her as the ultimate shallow consumer:
[Lolita] believed, with a kind of celestial trust, any advertisement or advice that appeared in Movie Land or Screen Land—Starasil Starves Pimples, or "You better watch out if you're wearing shirttails outside your jeans, gals, because Jill says you shouldn't. If a roadside sign said: VISIT OUR GIFTSHOP—we had to visit it, had to buy its Indian curios, dolls, copper jewelry, cactus candy. (2.1.7)
Lolita, as a typical American teenager has a deep affection for the shallow and meaningless culture industry, which already implies a sort of loss of purity. That she doesn't always comply with Humbert's appetite for sex is a source of enormous frustration to him; along these lines, he describes her as "A combination of naïveté and deception, of charm and vulgarity, of blue sulks and rosy mirth, Lolita, when she chose, could be a most exasperating brat" (2.1.7).
Ultimately, Lolita is a tough character to puzzle out because she simply does not easily fit into the victim category. She is, in spite of her treatment under Humbert, a very strong figure. It is certainly notable that she initiates the first sexual encounter – according to him, at least. From that moment on, she figures out how to get (almost) whatever she wants out of Humbert – new clothes, magazines, trinkets, and long vacations. She takes her victimization and uses it against him, teasing him for being a rapist and predator, even accusing him of murdering her "mummy."
But she doesn't run away until deep into their relationship, despite ample opportunity. When she does finally run away, it's into the arms of another predator, Clare Quilty. In her final encounter with Humbert, she is a disillusioned but practical young woman. She loves her husband (though isn't crazy about him as she was Clare Quilty) and bears no grudge against Humbert. She knows that what he did to her was deeply wrong – he "broke" her life, as she puts it – but finds hope in her relationship with her husband Dick and the impending birth of her baby.
It is dark to realize that as the novel begins, Lolita is already dead; but even the most astute reader would not understand that point from the Foreword, where her death (and that of her child) is announced: "Mrs. 'Richard F. Schiller' died in childbed, giving birth to a stillborn girl, on Christmas Day 1952" (Fore.3).