In the summer of 1976, the scheming Heather Grant is hired by Nurse Diana Taylor as the nanny of her young daughter, Martha. Coming from a lower class family, Heather got what she wanted by cheating. Desperately wanting the job, Heather gave Diana a forged letter of recommendation. She soon sets her sights on Dr. Monica Webber's husband, Jeff. After Jeff and Monica have a fight, Heather comforts him and they end up sleeping together. When Jeff suddenly disappears, Heather learns she is pregnant. After Jeff attempts suicide, he is shocked to learn Heather is pregnant. Heather fakes a suicide attempt hoping to win Jeff's affections. However, because Jeff refused to leave Monica, Heather decided she didn't want the child. She confides in her mother, Alice, her plans. Instead of aborting her child at Jeff's request, she sells the newborn to Diana and her husband, Peter for $10,000.
In 1977, after giving birth to Steven Lars, Heather takes $500 from Jeff and goes to New York City in hopes of becoming a famous model. Her landlady, Mrs. Hadley arranges for the Taylors to adopt her son while concealing Heather's identity from the Taylors. However, after Mrs. Hadley and a lawyer take their cut, Heather is only left with $1,800 of the $10,000. Instead of coming clean, Heather tells Jeff the baby was stillborn. To make up for her loss, Jeff proposes marriage. The two return to Port Charles where Heather begins spending a lot of time with the Taylors' new son, Peter "PJ" Taylor, Jr, who is actually her son. In 1978, Heather gets a little carried away with the amount of attention she gives to PJ. The Taylors let her go believing her obsession is unhealthy. Heather continues seeing her son in secret. Meanwhile, Heather and Jeff finally marry but they see very little of each other, as Jeff is working long hours to get his medical license. Though Heather learns she is pregnant again, she is still miserable. Ironically, Jeff wants to name their new child "Steven Lars" if it's a boy.
In 1979, Heather began her next scheme attempting to drive Diana Taylor insane in hopes of gaining custody of her son. Due to Heather's manipulations, Diana grows even more dependent on Heather to help with PJ. Heather later purchased LSD and put it in Diana's drinking glass. However, little PJ mixes up the glasses and Heather unknowingly drinks the drug. When Heather began hallucinating, Jeff was forced to have her committed to Pine Circle Sanitarium. With Heather away, Alice came to see her daughter's manipulations and Diana realized she'd lose PJ if she didn't marry Jeff.
1980โ1983
In 1980, Heather emerged from her state of delusion, faked catatonia and escaped from Forest Hills Sanitarium. She went to see Jeff but discovered he was now in love with Anne Logan. She then returned to Forest Hills and was later officially released. In 1981, Heather faked hysteria and convinced Jeff's brother and sister-in-law Rick and Lesley to send her back to Forest Hills. From there, Heather set her plan in motion to kill Diana Taylor and frame Anne for the murder. She escaped with a gun, only to find Jeff in bed with Diana. After killing Diana, Heather wrote Anne's name in blood next to Diana's body. After Anne rejected him, a heartbroken Jeff took little Steven Lars and left town. Jeff files for divorce while Police chief Burt Ramsey discovers another gun killed Diana, pointing the finger at Heather. Heather's new admirer, Joe Kelly refuses to believe that she actually killed Diana. It is soon revealed that Alice accidentally killed Diana in an attempt to keep Diana from killing Heather.
In the summer of 1982, Heather convinces her cousin, Susan Moore to go after the Quartermaine fortune for her newborn son, Jason, with Alan Quartermaine. Eventually Scott Baldwin takes on Susan's lawsuit against the Quartermaines. However, Heather and Scott have secretly been planning to steal the cash. Susan and Scott would become romantically involved much to Heather's dismay. In December 1982, Heather tricks Susan into giving her permission to raise Jason if anything were to happen to her. However, Susan soon catches on to Heather's schemes and convinces Scott to marry her so Heather can't get a dime of Jason's million dollar trust fund. Susan soon learns Heather and Scott were working together and bars him from getting any money. After Susan is murdered, Heather teams up with the illegitimate Quartermaine Jimmy Lee Holt in an effort to get custody of Jason; however, she eventually loses this battle to the Quartermaines.
2004
In June of 2004, Heather returned to Port Charles claiming she wanted to reconnect with her family. She moves into the Spencer home with Lesley to help take care of Lulu while her parents, Luke and Laura were absent. However, Heather was up to her old schemes once again. She began seducing the recently widowed, Edward Quartermaine, much to the dismay of his daughter Tracy. When Edward started being haunted by his late wife, Lila, Heather started keeping her distance. Later, Heather pretended to be overtaken by Lila's spirit and tricks the Quartermaines into believing Lila wanted Edward to move on with her. Knowing Edward wouldn't be easily convinced, she causes him to have a heart attack and is the only one who attempts to save his life, as the rest of his family believes he is faking. After he is released from the hospital, the two become engaged and they marry on October 20, 2004 at the Quartermaine cabin.
Heather's plans to get rich by killing Edward are stalled when he gives his entire fortune, to be with her. After Heather and Tracy have Edward committed, Luke helps bring Heather's schemes to light. Edward has the marriage annulled in November of 2004. Due to Luke's tricks, Heather accidentally admits to killing police officer Ross Duncan and framing Edward's granddaughter, Skye for the murder. Heather kidnaps Skye. Luke tricks her into releasing Skye by pretending to marry her. Luke tells the authorities of Heather's crimes. She is declared insane and sent off to Ferncliff Sanitarium.
2012-present
When Sam needs info for her child with Heather's cousin, Jason Morgan, she asks her to give her info for one cost to get Steven back in her life. Sam agrees and Heather tells her the info that Franco is Jason's twin. Sam then leaves and doesn't agree on Heather's deal. Soon after, Heather reaches Steven herself and he agrees she can come back into his life. Heather is then very happy and moves in with him.
After meeting Steve's girlfriend Olivia, she heads to the hotel where Luke is staying. She claims to want to be with him. She then "accidently" pours a milkshake on Luke's new close friend, Anna Devane.
Heather then go to see Ewen Keenan for a "mental checkup" made by Olivia.
Meanwhile, Steven is arrested for murdering a patient in Memphis. Heather is determined to get him free, along with his half-sister Liz Webber, and Olivia. It is then learned by Heather, that Steve's old colleague from Memphis who's now working at GH, Maggie Wurth, knew about the murder. Heather then thinks Maggie turned him in. Heather then invites Maggie to her apartment and poisions her ice-tea. She then dies and Heather makes it seem like a suciude and writes a note pretending to be Maggie saying she murdered the patient in Memphis.
