Mileva is a gifted young woman from Serbia who receives special permission to study mathematics and physics at a prestigious Swiss university. Born with a congenital hip defect that causes a limp, she grows up believing she is unmarriageable and pours her focus entirely into her education. At her boardinghouse, she finds an unexpected community of female scholars who support her ambitions. She possesses a deep intellect and views scientific theory as a way to understand the universe.

Albert is an ambitious and charismatic physics student at the Polytechnic in Zurich. Unlike his more traditional peers, he reads progressive books and values independent thinking, which immediately draws him to Mileva. He is highly intelligent but often clashes with his professors due to his unorthodox approach to academics and casual demeanor.

Marie is a world-renowned physicist who pioneered research on radioactivity. As a woman who successfully balances her scientific career with a supportive marriage, she serves as a powerful example of female achievement. Her public success and partnership with her husband represent the academic life Mileva aspires to build.

Lieserl is the first child of Mileva and Albert. Because her parents are unmarried at the time of her birth, her arrival brings significant social complications for her mother's academic career. She remains in Serbia under the care of Mileva's family while her parents reside in Switzerland.

Elsa is Albert's first cousin, the daughter of his mother's sister. She lives in Berlin and maintains contact with Albert, representing a connection to his German family roots and an alternate social circle.

Michele is a Swiss-Italian engineer and one of Albert's closest friends. He is a supportive colleague who frequently engages in deep scientific debates with Albert and his social circle, showing respect for Mileva's intellect when she joins their group.

Helene is a resident at the Engelbrecht Pension and becomes one of Mileva's closest friends. Like Mileva, she walks with a limp and faces societal prejudice due to her Jewish identity. She is fiercely independent, initially making a pact with Mileva to remain unmarried and dedicated strictly to academia.

Mileva's father is a hardworking landowner in Croatia who deeply values education. Recognizing his daughter's unique intellect, he defies gender norms of the 19th century by securing her admission into male-dominated academic spaces. He acts as her primary source of financial and emotional support during her early studies.

Mileva's mother holds traditional views on a woman's role in society. She initially views Mileva's academic ambitions as unfeminine and worries about her daughter's future due to her physical disability. Despite their early differences, she steps in to provide practical support and care when her daughter faces personal hardships in Serbia.

Professor Weber is an instructor at the Polytechnic in Zurich. He demands strict adherence to the traditional rules of academia and holds significant influence over his students' future career prospects. He is often dismissive of independent or arrogant behavior in his classroom.

Marcel is a mathematics student at the Polytechnic and a friend of Albert. He acts as a helpful colleague, offering Albert a connection to a patent office job when traditional academic employment opportunities fall through.

Milivoje is a Serbian chemical engineer who begins courting Helene. His presence challenges Helene's previous vow to remain a single academic, creating early tension in Helene and Mileva's friendship.

Ružica is one of the young women living at the Engelbrecht Pension. She enjoys fashion and café culture, helping Mileva experience the lighter, social side of the city outside of strict academic study.