Julia is Winston Smith’s Juliet. Is the name a coincidence? Probably not. A duplicitous and whimsical creature, her sexual allure inspires Winston to start the rebellious writings (because he fantasizes about her). She then acts as Winston’s ally in active rebellion, although her idea of revolt is more in-your-arms than up-in-arms. Julia is a dark-haired, twenty-six-year-old employed as a machine operator in the Fiction Department at the Ministry of Truth. Looking like a zealous Party member, she wears an (ironic) Anti-Sex sash around her waist, and always participates passionately during the Two Minutes Hate.
Julia’s other side is much more interesting. She is a woman with raging hormones and a cunning spirit. A highly sexual being, she sleeps with Party members regularly to satisfy her own desires. Does she really mean it as rebellion, or does she just want to get it on? You could argue either way. Winston would sure like it to be the former, and Julia does suggest that her acts are her own small rebellion. But still, she is generally uninterested in fighting the good fight. In fact, the reason she approached Winston with the "I love you" note was probably to start yet another illicit affair. She busies herself with community service and other orthodox activities so that she can escape the Party’s thoughtcrime radar. Clever gal.
When Julia and Winston fall in love, they commit the biggest possible offense against the Party because of the newly constructed, shared, private loyalty to one another. Supposedly, if you love a person, you have less love left to give to the Party. We’re thinking a little Beatles is severely needed here ("And in the end, the love you take is equal to the love you make.") But the Thought Police would have our heads for that. The moment Winston and Julia are captured signifies the importance of their bond. So what does it mean that the two betray each other? Perhaps that love is weak and feeble in the face of, um, rats. Or that, ultimately, people value themselves and their own safety more highly than their loved one. Or…you come up with one.