O'Brien's character creates paranoia through isolating his victims and toying with their minds. He amplifies their already existing paranoia from living in the dystopian society of Oceania. O'Brien drops vague notions that he is a part of a rebellious organization called the Brotherhood without outright confirming this notion to Winston. Winston believes that O'Brien is the only person he could trust and wants to join the Brotherhood.
When O'Brien captures and tortures Winston, he continues to toy with his mind, suggesting that perhaps O'Brien really once was against Big Brother and that he, too, was captured and tortured into accepting the Party. Even though Winston is being tortured by O'Brien, Winston seems to still cling to him as a mentor figure. He desperately wants to connect with someone he can trust and believe in, and O'Brien plays on this lack of trust in a society dominated by paranoia.