Maya is a bright, science-loving fifth grader in Chicago who struggles with self-confidence. When placed in a separate class from her lifelong friends, she experiences a deep sense of isolation and anxiety. She throws her energy into repairing an abandoned robot she discovers in a local corner store, finding comfort and scientific joy in the complex engineering project.

Ralph is an incomplete, barrel-shaped robot with a bucket-like head, flexible hinged arms, and tank treads for mobility. Originally designed to assist people in need, he represents an exciting engineering challenge for Maya. Once properly powered and activated by a specific keyword, he exhibits helpful functions and responsive behaviors that mimic friendship.

Mr. Mac is the kind, hardworking owner of Mac's Everything Store, which acts as a central hub for Maya's Chicago neighborhood. He is a community-oriented businessman who prioritizes helping his neighbors over turning a high profit. Seeing immense potential in Maya, he encourages her scientific curiosity by allowing her to take home a robot his son built.

Christopher is Mr. Mac's son, a highly intelligent engineering student who attended Stanford University. He created Ralph as a side project with the specific goal of assisting people in need. Through his meticulously detailed, color-coded notebooks, he serves as an inspiring academic role model for Maya's own scientific aspirations.

Maya's parents provide a strong, loving foundation for her and her brother. Her mother is an incredibly hardworking woman balancing two jobs with boundless energy, while her father maintains a close bond with Maya through weekly educational outings and diner trips. Together, they encourage Maya's interest in science while insisting she maintain her responsibilities.

Jada is one of Maya's best friends. She is eager to grow up and openly excited about the new school year. Placed in Ms. Montgomery's class for fifth grade, she is separated from Maya for the first time, causing a shift in their usually tight-knit dynamic.

MJ is Maya's other best friend, a small boy named after Michael Jordan despite having no aptitude for basketball. Like Jada, he is placed in Ms. Montgomery's class, inadvertently leaving Maya feeling isolated. He relies on his close friends to stand up for him when older kids tease him.

Zoe is the most popular girl in Maya's fifth-grade class. She is highly social and often seems to be at the center of attention. Her interactions with Maya are tense, as her outward behavior comes across as bullying or mocking to the more introverted Maya.

Elijah is a new student in Maya's class who recently moved from Indiana. He is tall and burly like a football player but wears slipping plastic glasses. He is friendly and eager to make connections, attempting to reach out to Maya despite her initial reluctance to engage with him.

Amir is Maya's younger brother. He is energetic and occasionally acts up during family outings, requiring attention from his older relatives. He is fascinated by Maya's technological pursuits and enjoys giving commands to Ralph.

Ms. Rodriguez is a fifth-grade teacher rumored to be the strictest educator in the school. She runs a disciplined classroom, calling on students who do not volunteer, which deeply intimidates Maya right from the morning roll call.

Ms. Montgomery is a fifth-grade teacher known for her fun and engaging classroom atmosphere. Jada and MJ are assigned to her class, much to Maya's disappointment.

Principal Merriweather is the head of Maya's elementary school. She is an authoritative figure who manages the school's logistics and discipline, enforcing the rules that separate the fifth-grade classes during recess.

Auntie Lou is Maya's aunt who helps provide educational and fun experiences for her niece and nephew. She is a supportive extended family member who fosters Maya's love for science by taking her to exhibits like the Power of Power.

Dr. Yazzie is a globally recognized expert in robotics with a specific focus on human-robot interaction. She serves as a high-level academic role model in the field of engineering.

Kai is a museum employee who runs interactive science demonstrations. He is impressed by Maya's deep knowledge of obscure batteries and rewards her scientific curiosity with a gift and a crucial mechanical component.

Terrance is a regular customer at Mac's Everything Store. He is a young man from the neighborhood who benefits from Maya's quick-thinking scientific advice about ripening fruit using ethylene gas.