How Brennan and, later, Breyer affected O'Connor.

From Cliff Sloan's piece in Slate about Joan Biskupic's new biography of Justice O'Connor:

[S]ome of [what is in the book] is new—an apparent rivalry between liberal lion William Brennan and O'Connor for influence on the court, and Brennan's clumsiness in his maneuvers; the effectiveness of Justice Stephen Breyer in reaching out to her. With Potter Stewart's departure in 1981 and O'Connor's replacement of him, Brennan seemed to have lost an important occasional ally. He viewed his new colleague with suspicion, and—though he is often thought of as the consummate court politician—he made the same mistake that Scalia would make several years later: He caustically attacked her, and if anything seems to have driven her away. Brennan's approach to cases became particularly arch and unyielding in his later years, and even when he had O'Connor's vote he could not get her to join his opinions. Breyer's style would prove far more hospitable to O'Connor than Brennan's broadsides; like her, he was attuned to the particularities of each case and searched for common ground.

The subject of the relationships among the justices and the effect on the decisions is highly interesting -- and exceedingly hard to study.