The irony of incest and friendship.
Claudia loves Gordon. Oddly enough, their incestuous sexual relationship comes to a natural end, and for the moment, it seems like they'll both adjust to the world and be alright. Their friendship itself is ironic, since a sexual relationship with one's own sibling might be expected to bring a tremendous amount of shame and embarrassment, but not for Claudia, at least not in the short term. Things change when they reunite later in the book.
The irony of Claudia's fierce personality.
By the time World War I tears the young sibling couple apart, Claudia doesn't have a very successful social life. This might seem to imply that Claudia is not successful with people, but as she proves in her career as a correspondent, she quickly makes a way for herself, standing up for herself and trusting her passion.
The irony of Lisa's birth.
When Lisa is born to her parents, Claudia and Jasper, Claudia has been dating Jasper for a while, but she still doesn't marry him. Not surprisingly, this doesn't bode well for Lisa and Claudia's relationship, and even worse, Claudia doesn't really enjoy the daily practices of motherhood, and would much prefer her life as a career reporter.
The irony of subjectivity.
By showing the history of the 20th century through her own point of view, Claudia finds that she has a whole history of Europe in her sense of self. Ironically, that point of view is subjective, but actually, it's fairly easy to use that subjectivity as a lens into the past, so in this case, the subjectivity of the narrative was actually effective, because it helps to paint the story in a personal, relatable way, instead of as a list of objective facts.
The irony of death and the narrative process.
Another central plot point is Claudia's last season on earth. She learns to grieve, right at the end, right when she is about to be grieved herself. She finds herself struggling to understand the love someone else felt toward her. It's ironic that at the last moments of life, Claudia finds herself grappling with the very first question of life: What does love mean for me? And in a roundabout way, that ties the entire narrative together. No matter how political and social constructs might work in the world, the most fundamental part of life is a person's experience, and that will always revolve around relationships, love for others, and love for self.
