Dahlia Carpenter is a supporting character who serves as the mother and manager of the young pop star Angela Carpenter. At 43 years old, Dahlia has a distinctive appearance, being short with a hunchbacked posture, thick eyebrows and lips, and purple hair and eyes. She is consistently seen wearing extravagant jewelry and lavish clothing, such as a black mink coat and hoop earrings. A notable characteristic due to symptoms of the Martian disease, Dahlia is of indeterminate or androgynous gender, which varies over time; during Angela's childhood, she typically presented as male.

In her youth, Dahlia was a famous actor, but she experienced a sharp decline in her career, eventually being forgotten as she entered her twenties. This personal history of losing fame and relevance is the primary driver of her motivations. Determined to prevent her daughter from suffering the same fate, Dahlia pushes Angela to achieve lasting stardom. When Angela decides to leave modeling to pursue a singing career, Dahlia stands by her side, providing support and encouragement while also managing her professional path.

Personality-wise, Dahlia is a strict and driven stage mother who wants Angela to succeed, often referencing her own past mistakes to guide her daughter away from a similar downfall. Despite her strictness, she is careful not to overstep, always giving Angela space and time for herself. She can be confrontational, particularly when she perceives a threat to Angela's career, but she also acts as a protective figure. For instance, she expresses concern to the producer Tao about whether he might be conducting an experiment on Angela, having researched his background in neuroscience and mind control.

Throughout the story, Dahlia is instrumental in launching Angela's music career. She brings Angela to the eccentric producer Tao, believing his unique approach will guarantee success. During the Mars' Brightest competition, Dahlia is a constant presence, sitting in the staff seats and often clashing verbally with the manager Gus Goldman, who represents the rival duo Carole and Tuesday. Their rivalry is characterized by bickering and using others as buffers to annoy each other, though these interactions also provide moments of dark humor. Dahlia's protective instincts are tested when she becomes a suspect after Tuesday is injured, and she firmly denies any involvement, instead confessing to a lesser, unrelated secret about signing a soda commercial contract.

Dahlia's character undergoes significant development. Her past is revealed to be troubled; she was arrested twice for injuring a person, and medication she once took made her unstable, which prompted physical abuse towards Angela in her childhood. Moreover, she kept the secret that Angela was adopted. As the series progresses, her health deteriorates, and she ends up in the hospital in a coma. In a poignant moment before her death, Dahlia briefly awakens, apologizes to Angela for keeping the adoption a secret, and promises that she truly loves her as her own daughter. Her death leaves Angela in a critically unstable state, overwhelmed by grief and the drugs she had been consuming, leading to her collapse during a performance.

Dahlia's notable abilities are not musical or performative but lie in her experience and acumen as a manager. Having been a famous actor herself, she understands the entertainment industry and uses that knowledge to strategically promote Angela, from hiring producers to making commercial deals. Her primary strength is her relentless, if sometimes flawed, dedication to her daughter's success, which she pursues with a fierce and protective determination.