Making friends and trying to figure out true friends from false ones is a major part of Northanger Abbey's overall plot, as well as Catherine's personal journey and development. Friendships in this book are subject to the narrative trajectory of growing up and maturing. Catherine has to trade in her whirlwind, fun, and ultimately shallow friendship with Isabella for a more mature and rewarding, friendship with Eleanor. Northanger Abbey makes observations, both comical and serious, on friendships. The book also questions what makes a good, or even a real, friendship.
Catherine has to learn how to be a good friend over the course of the novel.
When she is questioning Eleanor about Mrs. Tilney's death, Catherine behaves in a self-centered manner similar to Isabella, and disregards Eleanor's feelings.