Years ago, college students across the world adapted the principle of Six Degrees of Separation and turned it into a game known globally as "Six Degrees of Kevin Bacon", proving essentially that every person on the planet could connect themselves to the Hollywood actor through just five other people. Olive Kitteridge, the protagonist of Olive, Again, is an example of this principle as well. There is no particular plot to the narrative of the story; in fact, some of the segments seem to feature fairly random people who seem to have nothing that binds them together, until we learn that at one time or another in their life, they have known, or have known someone who has known, Olive Kitteridge.
Olive is starting to realize all the things she didn't know when she was a younger person, and they are turning out to be quite important, significant thing in terms of the way in which her life has affected other people. She didn't intend to have any effect on other people at all, but was just busy living; looking back, she can see that everything she has done, or said, or decided against, has had a knock-on effect that has deeply changed the direction of the life of someone else. This has been both positive and negative. Whilst being the best teacher she can be, for example, she has sometimes come across as rather brusque, and sometimes been considered a bit of a bully, but she also seems to have produced students who actually want to keep in touch with her. Two of the vignettes focus on her former students, and despite her rather sharp demeanor as their teacher, Olive proves herself to be approachable and also shows that she deeply cares about the students who have come through her classroom long after they have left their school days behind them. Both former students in the novel think positively about the influence Olive has had on them, but for Olive, that was just her doing her job to the best of her ability. She did not realize that she would be making such an amazing difference.
Not all of the differences Olive has made have been as positive. An example of this is her son, who seems to be mirroring her relationship with his father in his own marriage. Olive concedes that she was not always a particularly nice person, and sometimes she was especially mean to her ex-husband. When she sees her son getting a verbal dressing down from his wife, and meekly toeing the line, she realizes that she has given him a horrible blueprint for marriage, and immediately feels regret that she was not more circumspect in her word and behavior at the time.
Olive is both an entertaining protagonist and a cautionary tale to the reader, reminding us that we are the center of a ripple that moves outward; when she thinks her life is just affecting her, it is not. Each of the characters is tied to her even in the most tenuous of ways, but her being in their life has changed it in some way or another.