What does the following quote reveal about Winston's emotional needs?
"Having caught O'Brien's eye, Winston reflects that he wasn't even sure. . .whether O'Brien was friend or enemy. Nor did it even seem to matter greatly. There was a link of understanding between them that was more important than affection or partisanship."
In the bland, overly controlled world of Oceania, Winston simply wants to feel something. He needs to be able to have emotions, not necessarily to express them. So, when he thinks of O'Brien (even at the novel's end when O'Brien plays a more significant role in Winston's life), he likes that he feels something. He doesn't care if his feelings for O'Brien are positive or negative, at least they will prove to him that he exists, that he lives. The other characters in the novel who are not conflicted have lost their ability to care or even to want to care; Winston realizes this and also recognizes the danger of becoming like them.
This quote from Part One, Chapter Two reveals a couple of important things about Winston's emotional needs. First of all, it shows that Winston needs to feel a connection with another person. It does not matter that Winston and O'Brien barely know each other; Winston is so starved of human affection and genuine interaction that he is prepared to believe that O'Brien is connected to him.
Secondly, Winston needs to feel like he is not the only rebel in Oceania. Remember that O'Brien has not expressed any anti-Party sentiment to Winston but, as this quote shows, Winston has convinced himself that O'Brien is also against Big Brother. His only evidence for this is a "flash of the eyes."
Above all, this quote demonstrates that Winston needs to feel a part of something that is not related to Big Brother or the Party. He wants to break free from the Party's oppressive rule and is prepared to ally with anybody to do that.