Heather Grant came to town in 1976. She secured the job of nanny for Peter and Diana Taylor's little girl Martha by supplying a fake reference letter. Soon, Heather set her sights on Jeff Webber. After Jeff and Monica had a huge blowout over Monica lusting after Jeff's brother Rick, Jeff sought solace in Heather's bed, much to Heather's delight. Their night of passion created a baby, but Heather didn't share the news at first. She finally told Jeff about the baby when he was recovering from a bullet to the brain. He insisted she get an abortion so that he could stay with Monica. Furious, Heather faked a suicide attempt to try to gain Jeff's love. But Jeff paid no attention so Heather tried to order Jeff to leave Monica. When that didn't work, Heather decided to enact her plan to trade her baby for money to start a new life. She offered to sell her baby to Diana Taylor, who desperately wanted a sibling for Martha, for $10,000 but Diana ultimately said no. On the rebound after Monica filed for divorce, Jeff asked Heather to marry him. He later took back his proposal when Heather's ex-husband Larry Joe came to town and filled Jeff in on Heather's past exploits.

Heather finally gave birth to a boy in New York City and then sold it on the black market for $10,000. Heather's landlady arranged for Diana Taylor to adopt the boy without revealing Heather to be the mother. But once the sale went through, Heather's cut of the money was very small. Jeff tracked Heather to the Big Apple and Heather told Jeff the baby had died at birth. They bonded over her lie and Jeff proposed again. But their upcoming marriage was instantly tainted by the amount of time Heather spent with P.J. Taylor, Heather's son. She had become his nanny, but when Peter and Diana noticed her intense interest in their son, they fired her. Jeff and Heather wed in 1978, but Jeff's long hours at the hospital drove a wedge even further between the newlyweds.

When Heather became pregnant again, Jeff proclaimed that if it was a boy he wanted to name it Steven Lars. But Heather miscarried the baby while trying to prevent Jeff from learning the truth about their first child. She then became obsessed with regaining her baby from the Taylors. She managed to make Diana incredibly dependent on her and then planned to finish her off by putting LSD in her drink to drive her insane. Heather's plan backfired when she confused the glasses and drank the tainted one herself. She suffered hallucinations and Jeff had her institutionalized.

Diana then found out that P.J. was Jeff's son and she desperately decided she had to marry Jeff in order to keep P.J. But Jeff fell in love with Anne Logan and wanted to marry her. Jeff couldn't actually marry anyone since he was still married to Heather. Heather faked catatonia and escaped from the mental institution. She made her way back to Jeff's house where she spotted Jeff in Anne's arms through the window. Hurt, she returned to the institution for awhile before being released. But she soon began another plot to remove Diana from the picture. She faked hysteria in order to be returned to the institution to covertly carry out her plan. Before being institutionalized again, she had stolen a gun from the Webber house, and once she was locked up again, she hid the gun in her friend's doll. She later escaped the institution once again, intent on killing Diana. This time she found Jeff and Diana in bed together. Diana later told Jeff that he was P.J.'s father, and he stormed out. Heather quietly made her way back into Diana's apartment to kill her. Instead, she found Diana was already dead. She quickly decided to frame Anne for the murder by writing Anne's name in Diana's blood. Anne nearly went to jail for killing Diana but was later cleared. Jeff left town with his son to keep him safe from Heather. He later asked Heather for a divorce in order to marry someone else.

Detective Joe Kelly then turned to Heather as his prime suspect but fell in love with her instead. Heather confessed her intention to kill Diana, but she couldn't remember actually pulling the trigger. The real killer turned out to be Heather's mother, Alice. Alice had killed Diana to keep her from killing Heather and claimed that she had struggled with Diana over the gun Diana had pulled when it went off. Heather got six months probation for attempted murder and her mother got off for mental reasons.

Heather tried to seduce Scott Baldwin, but he was more interested in her cousin Susan. Alan had given Susan a large amount of money as part of a settlement with her. When she was later killed trying to blackmail the Quartermaines for more money, Heather teamed up with Jimmy Lee Holt. They tried to gain custody of Jason, Susan's baby, and Jason's trust fund.

Heather returned to Port Charles in 2004 under the guise of wanting to reconnect with her family. She convinced Lesley to allow her to move into the Spencer home so she could help Lesley care for Lulu Spencer in Luke and Laura's absence.

Heather's true intentions behind her return to town involved the recently widowed Edward Quartermaine and his money. Heather offered her condolences regarding the death of his wife Lila and spent time with Edward and supported him through his grief. Secretly, Heather fantasized about marrying Edward and then murdering him after she had a legal entitlement to his funds. Heather placed herself in closer proximity to Edward by offering to care for Lila's rose garden and he agreed.

Edward's daughter Tracy sensed that Heather's intentions toward Edward were not sincere after she witnessed a kiss between Heather and Edward. Tracy accused Edward of moving on too soon after Lila's death and Heather took the blame for the kiss, although Edward defended her. Tracy later tracked Heather down and offered her a large sum of money to leave town quietly instead of pursuing Edward but Heather did not take the money.

In the weeks after the initial kiss, Edward and Heather grew closer and shared another kiss until Edward pushed Heather away on his anniversary to Lila. He accused Heather of teaming up with Tracy so he would lose the contest Lila had set up in her final will and testament to determine the most worthy Quartermaine heir. Heather denied the accusations and was frustrated when Edward believed Lila's ghost was haunting him to keep him away from Heather.

Heather kept her distance from Edward until Tracy invited her to a family dinner at the Quartermaine mansion. Tracy hoped that Heather would seduce Edward into losing the contest as the most virtuous heir. Heather used the opportunity to convince Edward to give their relationship another chance and their evening ended with a kiss. A storm raged outside and knocked the power out so Edward offered Heather a room so she could spend the night.

Due to the chaos of the storm and the foreboding sense of danger, Heather pretended she had channeled Lila's spirit. The Quartermaine family doubted Heather's claim that she had been overtaken by Lila's spirit until she shared a few code words of significance that only Lila and her family would have known. In her trance, she claimed that Lila wanted Edward to move on and gave her blessing to a relationship between Heather and Edward. Later, Heather thanked the Quartermaine housekeeper Alice for keeping her secret that she had overheard the special words.

Edward remained unconvinced that Lila wanted him to move on and hesitated in his relationship with Heather. She responded by spiking Edward's drink during a family meeting and he collapsed as he clutched his heart. His family assumed that he was faking a heart attack to gain sympathy and ignored him but Heather responded. She made sure he received medical attention and accused his family of not caring about him. Heather remained by Edward's side while he was hospitalized and she ran into her son Steven. He wanted nothing to do with her but their heated exchange was overheard by Felicia Jones, the trustee of Lila's estate.

Heather tried to do damage control with Felicia but she decided to keep Heather away from Edward until she conducted a full investigation into her past. She was pleased when Edward invited her to move in to the mansion to care for him after he was released from the hospital and he and Heather became engaged. After she settled in, she arranged for Laura Spencer to be moved in her comatose state into the attic of the Quartermaine mansion. Heather sneaked away when she was able and visited Laura and revealed she had a plan to bring Luke out of hiding and back into town. Heather promised Laura she would keep Luke away from Skye Quartermaine. Despite Heather's meddling, Luke and Skye reconnected and they realized Heather had been intercepting their messages.

Edward was suspicious of Heather's frequent trips to the attic but she produced a portrait of Lila and claimed it was another sign that she blessed their union. Edward and Heather married at the Quartermaine cabin, although Tracy tried to interrupt the wedding. Heather was eager to consummate the marriage after the ceremony but Edward dozed off and called out for Lila in his sleep. When Monica learned of the union, she threw Edward and Heather out of her house and they moved into an apartment above Kelly's diner. Edward gave away his money and ELQ shares and took a job at Kelly's. He insisted he did not need money, only Heather, to make him happy.

The decision Edward made to give up his money bothered Heather and she worried about Edward's mental health. Tracy agreed with Heather and the women conspired to have Edward's mental health evaluated without his knowledge. The psychiatrist declared Edward mentally sound so Tracy and Heather bribed him to have Edward committed to a mental institution. After Edward was committed, Heather returned to the mansion to check on Laura, unaware that Tracy's son Dillon had spied on her.

Heather realized Laura had been discovered and moved her to another secret location. She also confronted Luke and assured him she would make sure Skye was out of the way for Laura's sake. Heather denied Luke's insinuations that someone had framed Skye for the murder of a police officer named Ross Duncan. Skye was frustrated with Heather's antics after she learned Heather had invested two million dollars of Edward's money in the Haunted Star and she went to Tracy.

Behind Heather's back, Tracy and Skye decided Edward needed to see how Heather was acting in his absence and they arranged for his release. Edward was disappointed with Heather and filed for an annulment. Luke tricked Heather into admitting she planned to kill Edward and he pretended that he would help her. When Heather made her move against Edward, Luke took his place and Heather was shocked to realize she had almost choked Luke. Skye, Edward, and Luke heard Heather profess her love for Luke and she admitted to killing Ross Duncan and framing Skye.

Once Heather realized she was caught, she held a knife on Skye and took her hostage. The women hid at Wyndemere and Skye tried to reason with Heather, but she insisted she was actually Laura. Heather silenced Skye by injecting her with a hallucinogenic drug. Luke found the women and he questioned Heather about where she had taken Laura. Heather promised she would tell Luke after they were married and she went along with Luke's decision to marry her at the Quartermaine estate.

Heather was confused when she arrived at the mansion and saw several guests and Emily Quartermaine in a wedding gown. Luke explained that Emily had dressed up because she wanted to be just like Heather. Luke stalled the ceremony by suggesting that Skye should be present to witness their nuptials. Heather agreed and relayed Skye's whereabouts. While Heather was out of earshot, Luke updated the police on Heather's crimes and she was declared insane and taken to Ferncliff. She did not reveal Laura's location.

In 2012, Heather received a visit at Ferncliff from Jason Morgan's wife Sam. She asked Heather several questions about Jason's birth since Heather had been the birthing partner for Jason's mother. Sam claimed that she needed to know about Jason's birth since she and Jason were expecting a child of their own. Heather agreed to share what she knew about Jason's birth in exchange for Sam's promise to deliver a letter from Heather to Steven Lars. Heather shared that Susan had passed out after giving birth to Jason and only a nurse had been present at the delivery. While Susan was unconscious, she gave birth to a second son and Heather sold the child to the nurse without ever telling her cousin Susan about the other child. Sam garnered Heather's wrath after she heard the information but did not take Heather's letter to Steven Lars.

Shortly after Sam's visit, Heather was declared sane and released from Ferncliff into the care of her son. Steven Lars informed his mother he went by the name Steve and he agreed to take responsibility for her and she moved in with him. Heather was glad to be free but she was not pleased with everyone she encountered after her release. One person Heather did not care for was Steve's girlfriend Olivia Falconeri. Olivia sensed Heather's dislike of her after

Heather made a few snide remarks to her. Olivia spoke to Steve and advised him to obtain a second opinion about Heather's sanity. Steve did not immediately agree with Olivia until he saw Heather interact with Luke and his roommate Anna DeVane at Kelly's. Heather made cutting comments toward Anna and insinuated that she and Luke shared a special past together. When Luke did not respond favorably toward Heather, she spilled a drink on Anna. Steve witnessed his mother's actions and decided to seek another opinion regarding Heather's mental health and he took her to the hospital to meet Dr. Ewen Keenan.

While Heather was at the hospital meeting Dr. Keenan, she ran into Sam and she saw that Sam had an order for a paternity test. Heather pieced together that Jason's twin might be the father of the child and that Jason was unaware that he had a brother. Heather threatened to share the news herself with Jason to repay Sam for reneging on her promise to bring the letter to Steve. Sam countered with her own threat to inform Steve about Heather's actions in the sale of Jason's brother. Heather decided to remain quiet but she told Sam she hoped the baby was not Jason's.

Heather's focus shifted from flirting with Luke and threatening Sam after she learned that Steve had been arrested by the Memphis police and was charged with the murder of a patient. Heather overheard a conversation between Olivia and her son Dante in which Olivia explained that Steve had intentionally allowed his patient to die so a patient of Dr. Maggie Wurth's could live. Heather was shocked by what she heard but she vowed to fix the situation for her son.

Heather had met Maggie briefly when Maggie caught her looking at confidential hospital records. Heather fought Maggie for the papers and Maggie made a comment about Heather being crazy. After Steve's arrest, the women were cordial to one another and Heather asked Maggie to write a letter of recommendation on Steve's behalf. She also asked Maggie to give her a ride home.

Unbeknownst to Maggie, Heather had stolen a lethal dose of medication from the hospital and she mixed the medication in a glass of iced tea. Maggie ingested the poison and died. Heather cleaned up the evidence and forged a suicide note in which Maggie confessed that she, not Steve, had killed the patient in Memphis. As Heather had planned, Steve was released from jail.