Emilia is a hardworking artist and waitress living in New York City. Ten years earlier, she lived in Todos Santos, California, where her parents worked as domestic staff for the wealthy Spencer family. She is pragmatic and highly skeptical of extreme wealth, always prioritizing her family's survival over her own pride. Despite her difficult financial situation, she maintains a strong sense of morality and resilience against intimidation.

Vicious is a wealthy and highly intelligent lawyer who runs an investment firm with his high school friends. As a teenager, he ruthlessly bullied Emilia, dubbing her "Help" due to her parents' domestic employment. He relies on his vast wealth as a shield against emotional vulnerability, harboring deep resentment toward his family due to childhood trauma. He maintains strict control over his surroundings to hide his personal scars.

Jo is Vicious's highly superficial and wealth-obsessed stepmother. She lives in the Spencer family mansion in Todos Santos and employs Emilia's parents. She is deeply concerned with maintaining her status and securing her ailing husband's fortune, making her a direct target of Vicious's schemes for revenge.

Rosie is Emilia's younger sister, who lives with a chronic illness called cystic fibrosis. Her fluctuating health requires expensive medication, which drives many of Emilia's financial decisions. She is perceptive and deeply wary of Vicious due to his past treatment of Emilia, frequently advising her sister to keep her distance from him.

Dean is one of Vicious's closest friends and a fellow member of the high school group known as the "Four HotHoles." He comes from a wealthy background and eventually runs the Los Angeles branch of Fiscal Heights Holdings. Unlike Vicious, Dean is charming and outgoing, preferring casual, short-term romantic encounters over serious attachments.

Trent is a member of Vicious's tight-knit high school friend group in Todos Santos. Unlike his extremely wealthy peers, he comes from a less affluent background and initially relies on athletic scholarships for his future. As an adult, he works alongside his friends as a partner at their investment firm.

Jamie completes the wealthy friend group at All Saints High School. He grows up to be a business partner at Fiscal Heights Holdings. He is observant of the group's dynamics and often serves as a sounding board for Vicious's personal and professional maneuvers.

Baron Sr. is Vicious's wealthy father and Jo's husband. He is a cold, transactional patriarch who values money and status above personal relationships. He consistently sides with his wife over his son, initiating a deep rift that defines Vicious's adult life.

Daryl is Jo's brother and a violent presence in the Spencer household. He physically abused Vicious throughout his childhood, leaving severe scars. His actions cast a long shadow over Vicious's psychological development and drive much of Vicious's anger.

Charlene is Emilia and Rosie's mother. She works as a housekeeper for the Spencer family in Todos Santos. She is hardworking and grateful for her employment, remaining largely unaware of the extent of the bullying her daughter faces from her employers' son.

Eli is Dean's father and a professional associate who handles legal matters for the Spencer family. He maintains a polite, professional demeanor even when managing the friction between his son and Vicious.

Georgia is a wealthy classmate at All Saints High School who partakes in bullying Emilia for her lower socioeconomic status. She maintains a casual, transactional relationship with Vicious that briefly resurfaces in their adulthood.

Rachelle is Emilia's manager at a New York City bar. She is friendly, sympathetic, and accommodating when Emilia faces personal and financial difficulties.