Sofia Taylor fulfills the roles of chaperone and assistant to Al Lyon, rooted in her family's generational service to the Lyon household. Her mother worked as a domestic maid and babysitter for Al's family, resulting in Sofia growing up alongside him in a relationship she characterizes as sibling-like. When her mother could no longer work, Al's father formally requested the fourteen-year-old Sofia to assume the chaperone position, a duty she maintains into adulthood.

Her responsibilities include overseeing Al's activities and well-being, particularly during his involvement in the Trans-America Wild Race. She displays genuine concern for his safety alongside his competitive drive, mirroring their deep personal connection. While typically gentle and supportive, she possesses a curious and active nature, occasionally engaging in surprising actions like operating experimental vehicles such as Appare's scooter.

A significant event unfolds when outlaw Gil T. Cigar, later revealed as Gil the Butcher, kidnaps Sofia during a train journey. He holds her hostage to demand a ransom equal to the race's prize money, triggering a determined rescue mission by Al that highlights her importance to him and the narrative. This captivity directly challenges her protective role.

Throughout the race, Sofia maintains a supportive presence focused on Al and his companions. Her interactions reveal a balance between her official duties and sincere care for those around her, extending concern even to rival participants like Appare and Kosame. Visually, she is defined by shoulder-length orange hair, blue eyes, and distinctive attire: a yellow dress, purple thigh-high boots, a matching hat, and gloves.