When Winston visits O'Brien in 1984, what is his motivation and what limits does he set on his involvement in the Brotherhood?
In 1984, Winston visits O'Brien on the pretence that he is borrowing the newest edition of the Newspeak dictionary. In truth, however, Winston visits because he hopes that O'Brien is a "political conspirator," as his thoughts and dreams have suggested. During their conversation, Winston's hopes come true when O'Brien informs him that the Brotherhood, a secret organisation which seeks to bring down the Party, really does exist and that it is headed by the Party's number one enemy, Emmanuel Goldstein.
Winston consents to become a member of the Brotherhood and agrees to carry out a number of activities, including murder and sabotage. He does set a limit to his involvement, however, when O'Brien asks if he is prepared to separate from Julia and never see her again. Winston hesitates in answering this question before finally saying "no." Winston thus stands firm in his commitment to Julia and demonstrates his belief that love is more important than overthrowing the Party.
Winston visits O'Brien because he believes there is a conspiracy against the Party, and he thinks Winston is apart of it. He does not believe in the principles of Ingsoc. He says he will do anything to fight against the Party except to seperate from Julia.