Vampirism is the most obvious motif and symbol in the story. It is not a theme in itself, but is used to flesh out all the themes to varying extent. Given the genres embodied by Twilight, the vampire represents the unleashed id, the release of intellect to a more pure, animal passion. The desire and romance that comes with the vampire romance is the notion of passion or love as an insatiable hunger that requires the very essence of the loved one. Of course, passion can also be quite dangerous, and a hunger must know limits or will threaten everyone involved - this is shown by the appearance of James late in the book. Edward knows best the importance of curbing his vampire appetite, as it comes in direct conflict with his romantic desire for Bella. Vampires can also stir great passion in those they touch: Sam Uley and Billy Black are repulsed by them, even with the Quileute agreement; the Cullens are all admired for their great beauty by those who encounter them. Perhaps most striking of all, Bella is a human whose close interaction with Edward makes her more passionate and hungry for her new love, as seen by the kisses where she becomes more aggressive than Edward, forcing him to back off. Thus, her decision at the end of the novel to eventually become a vampire not only reflects her love for Edward, but her decision to embrace the passionate side of herself as well.
Time - or rather, one's sense of time - is used to reflect the experiences of characters, telling readers the importance of what they're going through and how they feel about it. For example, Bella notes how time in Forks is a blur, except for the times with Edward when every second is sharply remembered. Similarly, when she runs to save her mother at the dance studio, she notes how time drags even though she is running. Further, there are clear distinctions in time between species --that is, vampire time is quite different from human time. Vampires have abilities that make them move much more quickly than humans if they desire - as a result, though, they show greater patience since they can react more quickly and also see the world from an immortal perspective.
Cars are an important symbol in the book, reflecting their owner in some manner. Bella's red truck is her first solid adjustment to Forks, paving the way for what follows. Further, the clumsiness and slowness of her vehicle reflects her own human failings, especially compared to the faster and more exotic Volvo possessed by Edward. Mike Newton drives a Suburban, indicating the affluent middle-class value he possesses as the son of successful shop owners. Jacob likes to assemble cars, which shows how he wishes to make good use of whatever he can find - a reflection on the poverty and diminished status he inhabits. Emmett drives a rough-and-tumble Jeep, a show of his own personality; Rosalie drives a convertible BMW, indicating how easily she attracts attention to herself with her beauty. Last but not least, the Mercedes with tinted windows that Alice and Jasper drive to Phoenix with Bella is an excellent symbol of the Cullen family in general: it is rich and elegant and the cause of envy, but the tints make clear they are hiding in plain sight.
School is an important motif, as the community of peers that is central in Bella's life. Many scenes occur in the cafeteria, though the socialization process takes place throughout the day and even involves extracurricular events such as dances and prom. Two particular classes factor into the novel in a significant manner: Biology and Gym. Biology class is shared with Edward, so some of the drama which unites them takes place there. When blood is spilled - albeit in a routine lab experiment - Bella and Edward are drawn closer together through an unusual chain of events. Moreover, biology as a concept also drives the two together: Bella is the perfect prey for Edward as a vampire, and he must resist that for their mutual happiness. Gym class is a reminder of Bella's clumsiness, as she places herself and her fellow students in very mild danger. She repeatedly refers to how Gym class goes, and how her classmates protect her and themselves from her lack of sporting ability. Further, it is also the sight of social clumsiness, as she has to deal with Mike in that class, not always in the smoothest manner. Thus, when she attends her prom in the gym, she is redeemed somewhat for her past clumsiness, while the school setting in general shows how much she has adjusted to her new home.
Superheroes are another motif, referred to explicitly in two parts. As they
get to know each other, Bella jokes that Edward may be Batman or Spider-Man
and even refers to Spider-Man's origin when asking Edward where he got
his powers. At the end of the novel, Bella refers to Superman and Lois
Lane in one of her arguments for becoming a vampire. A forward-thinking
young woman, she does not want to be a constant damsel in distress - the
traditional view of Lois Lane - but instead wishes to be a true match
by taking on super-powers herself - that is, become a vampire. This general
superhero analogy is also useful in that it tends to further romanticize
Edward and remove him from the more horror-related imagery associated