Dahlia Hawthorne was born to Morgan Fey and a wealthy jeweler, with a twin sister named Iris. Because her mother lacked spiritual power, leadership of the Fey clan passed to Morgan's younger sister Misty. Their father divorced Morgan and took the twins, though Dahlia believed they were abandoned due to their own lack of spiritual abilities. After their father remarried, the family grew to include a stepsister, Valerie Hawthorne. Dahlia persuaded her father to leave Iris at Hazakura Temple, viewing her as a nuisance.

At age 14, Dahlia arranged a fake kidnapping with Valerie and her tutor, Terry Fawles, targeting a two-million-dollar diamond from her father. During the exchange on Dusky Bridge, Valerie shot Fawles, and Dahlia jumped into Eagle River below, taking the diamond with her. Fawles was convicted for her supposed murder. Valerie secretly recovered Dahlia and helped craft a new identity for her as "Melissa Foster".

Five years later, Fawles escaped prison and arranged to meet Valerie at Dusky Bridge to discover the truth. Valerie informed Dahlia of her intent to confess, leading Dahlia to murder her stepsister. Dahlia hid the body in the trunk of a car Fawles had stolen and posed as Valerie during the meeting. At Fawles' trial for Valerie's murder, Dahlia testified against him under her alias. Defense attorney Mia Fey exposed her true identity, but Fawles committed suicide in court by drinking poison from a necklace he and Dahlia had pledged to use if they ever distrusted each other.

Six months later, Dahlia poisoned prosecutor Diego Armando's coffee using poison stolen from her then-boyfriend, Doug Swallow, a pharmacology student. She fled to the courthouse reading room and gave the poison vial, concealed in a necklace, to Phoenix Wright to dispose of evidence. Armando fell into a coma. Suspected by authorities, Dahlia enlisted Iris to retrieve the necklace from Wright. Iris assumed Dahlia's identity at Ivy University to protect her sister and began a relationship with Wright to reclaim the evidence.

After eight months, with Iris unsuccessful, Dahlia attempted to kill Wright by poisoning his cold medicine. She encountered Swallow, who was warning Wright about the stolen poison. After Wright pushed Swallow and left, Dahlia electrocuted him with a downed power line and planted the poisoned medicine on him to frame Wright. During Wright's trial, Mia Fey defended him and exposed Dahlia as the murderer. Dahlia was convicted and sentenced to death.

While imprisoned, Dahlia was visited by Morgan Fey, who devised a plan for Pearl Fey to channel Dahlia's spirit to kill Maya Fey, ensuring Pearl would become the Fey clan master. Dahlia agreed to seek revenge against Mia by targeting her sister. Dahlia was executed by hanging.

One month after her execution, Morgan's plan was set in motion at Hazakura Temple. Diego Armando, now known as Godot, intervened by having Misty Fey channel Dahlia first. Dahlia, channeled through Misty, attacked Maya but was stopped when Godot impaled her with a sword-cane, killing Misty. Maya then channeled Dahlia and locked herself in the Inner Temple. During an earthquake, Dahlia switched places with Iris, locking her inside and posing as her during the subsequent trial for Misty's murder.

In court, Dahlia, masquerading as Iris, maintained her innocence until Phoenix Wright exposed her. Cornered, Dahlia claimed she could not be punished due to being dead. Mia Fey, channeled through Pearl, countered that Dahlia's punishment was eternal existence as a miserable failure. Dahlia's spirit was then exorcised, vanishing in a burst of flames.

Dahlia Hawthorne was characterized by a manipulative and selfish nature, often presenting a sweet and innocent façade to deceive others. She expressed no remorse for her actions, which included multiple murders, attempted murders, and manipulative schemes aimed at personal gain or covering previous crimes.