Just as keys and Katherines show up when you reconcile yourself to their absence, Colin reflects, his “Eureka” moment happens as soon as he accepts it never will. It feels to him “like a thousand orgasms all at once, except not as messy.” He immediately sketches a graph and captions it, “Where x = time, and y = happiness, y = 0 beginning of relationship and breakup, y negative = breakup by m, and y positive = breakup by f: my relationship with K-19.”
Colin’s association between his romantic life and his intellectual achievement is so strong that he experiences the “Eureka” moment as a kind of sexual pleasure. His immediate desire to capture that pleasure by modeling his relationship mathematically suggests that what Colin most strongly desires is not necessarily Katherine XIX but rather a failsafe way to understand and control the outcome of any relationship so that his plans for the future cannot be derailed again by another person.
Lindsey returns with a new shirt and a first aid kit while Colin is finishing up the sketch. She tries to test him for a concussion by asking him simple questions like the day and time. Hassan asks much more difficult questions, such as the name of the junior senator from New Hampshire in 1873, and Lindsey learns that Colin has an impressive repertoire of historical facts. She in turn surprises him by referring to Millard Fillmore. Colin wonders if he was too quick to judge her unintelligent for living in rural Tennessee and reading Celebrity Living.
Lindsey’s interruption of Colin’s sketch suggests that despite Colin’s attempts to preclude interruptions of his plans by future romantic partners, some factors might simply be out of his control or understanding. Lindsey and Colin discover each other in this moment to be more intelligent than first impressions suggested.
Hassan grabs Colin’s notebook, and Colin explains that he is trying to write a Theorem to predict relationship outcomes. Hassan says the theorem idea is “interesting” which is the highest compliment he can give Colin. Lindsey looks at the notebook and asks what a K-19 is. Colin briefly describes his relationship history. Lindsey laughs and says she has dated only one boy, and it’s funny because his name is Colin (The Other Colin).
Hassan’s interest in the Theorem seems to be in part because it could be useful in the real world. However, the idea that relationships can be predicted with any precision is immediately undermined by the arbitrary coincidence that Lindsey’s boyfriend happens to share a name with Colin.
In a section called “The Middle (of the Beginning), Colin reflects on how Katherine I became his first girlfriend. He was in third grade when his parents decided that his “sociological well-being” was enough of a lost cause that they would only have him attend school three hours a day. They hired his lifelong tutor, psychology professor Keith Carter, to talk at Colin the rest of the day. Krazy Keith was Colin’s father’s friend and “the closest thing Colin had to a best friend” because he never gave him an Abdominal Snowman.
Colin’s romantic life began at a very young age, meaning that he has defined himself in relationship to his girlfriends for more than half his life and through all the pivotal stages of self-definition that happen during adolescence. Again, the narrator reminds the reader that Colin has had precious few other relationships with his peers, making him feel lonely around people his age when he is not dating.
Krazy Keith’s daughter would sometimes accompany her parents to dinner parties at Colin’s house. One night, one of these dinners devolved into Katherine watching Colin study Latin. After a time, Katherine began asking Colin why he learned so many things so quickly. She kept asking him “why,” no matter how he responded. Eventually he got tripped up when she asked why Ovid lived in Rome when they spoke and wrote Latin. He told her it was a good question, and she asked him to be her boyfriend. He said yes and had his first kiss, “and it occurred to Colin that the kiss didn’t feel nearly as good as the sound of her asking if she could be his girlfriend.” This Katherine eventually became to Colin “The Great One,” “Katherine I,” and “Katherine the Magnificent.”
Colin first begins paying attention to Katherine I when she asks him about his intellectual pursuits. Combined with the fact that Colin is less interested in the kiss than in hearing that Katherine I wants to be his girlfriend suggests that Colin began his romantic career looking for veneration and admiration for his intellectual achievements. The slightly adversarial nature of the conversation suggests that although Colin conflates intellectual and romantic achievement, they have from the beginning been slightly at odds for him.