Winston first mentions a "dark-haired coworker" from the Fiction Department in Book One, Chapter I. This is a Party woman for whom Winston has, at once, intense sexual desire and hatred. It is not until after she passes Winston the love note, and just before the two have sex, that we learn of Julia’s name in Book Two, Chapter II.
Julia participates as a fervent Party member in the Two Minutes Hate.
Julia shoots Winston some lusty looks in the canteen, and Winston fancies her a member of the Thought Police.
Julia follows Winston into the prole district one night, and Winston contemplates smashing her head in with the glass paperweight he just bought from Mr. Charrington’s shop.
Julia encounters Winston in the corridor at work, and passes a note bearing the message "I love you" to him.
Winston and Julia arrange for a meeting in the countryside. They profess their love and/or lust for each other. Then they have sex.
Winston and Julia begin a secret love affair, meeting in clandestine places presumably away from telescreens and hidden microphones. They generally make love, fall asleep, enjoy real coffee and sugar and bread, and then chat about overthrowing Party politics. Their special hideout is in the room Winston rented atop Mr. Charrington’s shop.
Winston and Julia visit O’Brien together, and declare their loyalty to the Brotherhood.
One evening after Hate Week, after falling asleep reading Goldstein’s manifesto, Winston and Julia are arrested, beaten, and taken away to the Ministry of Love.
According to O’Brien, Julia betrays her love for Winston very easily upon entering the Ministry of Love. This is presumably because of the physical torture she was subjected to.
According to Winston, he and Julia met on the streets in March, 1985, though neither felt positively towards the other. Julia suggested half-heartedly that they must meet again, but neither carries the suggestion out.