In My Brilliant Friend, the author presents a complex portrait of female friendship. Lila and Elena grow up alongside one another and have a rather dark relationship with one another. Oftentimes, their friendship can be toxic, full of jealousy and competition. It is, however, this competition that encourages both girls to become more ambitious and fight for their dreams.

As young children in school, Elena and Lila compete in school. Academically, Lila is brilliant and outspoken, while Elena is also intelligent; she is thoughtful and observant but more reserved and less confident in her abilities. Lila's prodigy forces Elena to push herself to keep up with her friend, ultimately leading to her own academic success.

Even though Lila, whose parents fail to support her in her academic endeavors and refuse to pay for school, is extremely jealous of Elena, who continues schooling and receives numerous academic accolades, Lila starts referring of Elena as her "brilliant friend." Lila encourages Elena to never stop studying and praises her accomplishments. In the same vein, Elena is jealous of Lila's brilliance and effortless intelligence yet supports her friend's writing endeavors and is enamored by the novel Lila wrote, "The Blue Fairy," and even takes it to her teacher Maestra Oliviero to show it off.