O’Brien is an Inner Party Member whom Winston comes to greatly admire. He is described as a brutally ugly man with an imposing presence. Winston believes that O’Brien may also harbor anti-Party sentiments and becomes fixated on the idea that O’Brien may be a member of the Brotherhood. Winston is proved correct when a few months after his affair with Julia begins, O’Brien approaches and invites him to join the Brotherhood. However, after Winston and Julia are arrested, O’Brien reveals that he was always a Party loyalist. O’Brien takes the lead during Winston’s rehabilitation, “saving” him and making him into the “perfect” Party member.

Most of the information about O’Brien is unreliable. However, his status as an Inner Party member offers a glimpse at the privileges enjoyed by the upper echelons of Party membership. O’Brien lives in relative luxury, with access to good wine and cigarettes. He can even turn off his telescreen if he wants to. The freedoms enjoyed by the Inner Party in comparison to the Outer Party and proles suggest that maintaining the status quo is ideal for most Inner Party members.

O’Brien makes it clear that he has watched and studied Winston closely over the years. He knows exactly what to say in order to trap Winston, such as quoting what Winston has said on other occasions. His habit of adjusting his glasses endears him even further to Winston, who views the gesture as friendly and disarming. O’Brien intentionally positions himself as a mentor figure, someone who will teach and guide Winston through both rebellion and rehabilitation. Winston trusts O’Brien—even when Winston is being tortured, he still views O’Brien as his “protector” and “friend.”

O’Brien claims to genuinely care about Winston. O’Brien believes their minds are similar and says he took a special interest in Winston because he admired him. Though he tortures him, O’Brien says it will make Winston a better Party member. He views Winston’s rebellious thoughts as a disease and hopes to “save” him. O’Brien proves masterful at doublethink and genuinely believes that 2+2=5. In his mind, definitive reality does not exist; the Party shapes reality. Winston is astounded by O’Brien’s “lunacy” but also impressed by his intelligence. For Winston, O’Brien is his intellectual superior. As a result, Winston is unable to entirely resent him. Despite everything, O’Brien makes Winston feel understood.

O’Brien’s true relationship with the Brotherhood is left open to interpretation. He claims that The Theory and Practice of Oligarchical Collectivism, allegedly written by Emmanuel Goldstein, was actually written by the Party. He refuses to confirm or deny the Brotherhood’s existence for Winston. However, when Winston expresses his belief that O’Brien has been caught by the Party, O’Brien remarks that the Party “got [him] a long time ago.” By one interpretation, this line implies that O’Brien has always been loyal to the Party. However, it can also suggest that O’Brien was rehabilitated and indoctrinated into the Inner Party. This leaves open the possibility that he was once a member of the Brotherhood or at least resisted joining the Party.

Ultimately, O’Brien’s defining characteristic is his dogmatic belief in the Party. He believes that so long as someone is committed to the Party, “then all that they are will continue to be so long as the Party exists.” He believes that Big Brother will live forever. The Party has no grand mission or purpose beyond obtaining power for power’s sake. According to O’Brien, “If you want a picture of the future, imagine a boot stamping on a human face—for ever.”