Olivia grew up in Bensonhurst and was involved with Sonny Corinthos as a teenager. She became pregnant with Sonny's child but did not tell him. Clueless that Olivia was pregnant with his child, Sonny moved on and pursued her cousin Connie. Olivia gave birth to a son, Dante Falconeri, and told her relatives and friends that his father could be any one of three or four men she was sleeping with at the time. Connie knew the truth about Dante's paternity but kept the secret even as she left Bensonhurst, Sonny, and her family and started a new life as Kate Howard, Editor-In-Chief of a successful fashion magazine.
Olivia and Connie became estranged because of Connie's decision to leave her family and create a new life, but she kept up with Connie's accomplishments as Kate over the years through newspaper and magazine articles. Everything came back together years later when Olivia ran into Sonny at a bar and he informed Olivia he was marrying Kate and invited her to go to Port Charles and be Kate's maid-of-honor. Kate made it down the aisle to Sonny, only to be shot at the altar. Olivia was heartsick as she tended to her wounded cousin and waited for an ambulance to take Kate to General Hospital. Olivia made all the medical decisions regarding Kate's care and remained in Port Charles to care for Kate while she recuperated.
After Kate recovered, Olivia decided to remain in Port Charles and began working for Jasper Jacks as operations manager at the Metro Court Hotel. All the while, Kate urged Olivia to finally come clean with Sonny and tell him that she had given birth to his son all those years before, but Olivia refused, and Sonny remained clueless for the time being.
Olivia had no idea her past and present would collide until her son, Dante, arrived in town on an undercover assignment, using the alias Dominic Pirelli, and infiltrated the Corinthos crime family. Olivia begged him to get transferred, but he refused. For months, she watched Dante interact with his father and the family he didn't know he had. During this period, Olivia became involved with Johnny Zacchara, much to the dismay of both Sonny and his wife, Claudia, who was Johnny's sister. When Claudia learned Dominic's real identity, she attempted to use the information to break Olivia and Johnny up for good. Claudia's best efforts failed, and Olivia and Johnny remained together.
Despite all of Olivia's attempts to keep Dante's identity and paternity hidden, the whole world discovered her secret on the day of Josslyn Jacks's christening. Dante was close to finally serving a warrant on Sonny for murdering Claudia, but he held off so Sonny could spend a bit more time with his family. Before the christening, Sonny learned that Dante was in fact an undercover cop, but he still had no idea he was Dante's father. Sonny called Dante to his home for an urgent meeting and shot Dante point-blank in the chest after the two exchanged harsh words.
When Dante was a no-show at the christening Olivia panicked. She immediately went to Sonny's house and heard a gunshot as she entered. When she walked into the office, she found Dante lying on the floor and screamed to Sonny that he had shot his own son. Olivia was beside herself with rage and grief. Dante recovered, but his relationship with his mother soured as he came to terms with his mother's lies about his paternity.
In time, Dante understood why Olivia had protected him from Sonny, and he let go of some of his anger. Sonny, on the other hand, thought things might have turned out differently if Olivia had told him the truth and blamed her for his inability to form a relationship with his son. Olivia vehemently defended her decision to lie so that Dante would not grow up in the mob. When Olivia took the stand at Sonny's trial, Sonny was sure she would implicate him in Claudia's murder, but Olivia said nothing to incriminate him. After Dante revealed that it was Michael who had killed Claudia and Michael was sent to prison, Olivia was frantic with worry that Sonny or Jason would kill her son for his betrayal and begged them not to harm him.
Johnny was making plans to buy a penthouse and wanted Olivia to move in with him. Although she loved him, Olivia didn't think it was a good idea. Olivia was livid when Johnny started dating Sonny's daughter Kristina, even though it was just for show. Kristina was angry at her father, and Johnny knew it would incite Sonny. It was obvious to Olivia that Johnny loved his vendetta against Sonny more than he loved her. Johnny eventually tried to win Olivia back, to no avail.
After Johnny was shot in a confrontation with Sonny, Olivia begged Johnny to live so she could tell him how much she loved him. Olivia knew Johnny wanted to frame Sonny for the shooting and implored him to tell the truth that Sonny shot him in self-defense. When Johnny recovered, he and Olivia decided to give their relationship another chance.
One night when Olivia opened the door to Johnny's penthouse, she found him with Lisa Niles. Lisa was illegally treating Johnny for a gunshot wound. Lisa and Johnny tried to cover it up by implying they were lovers, and Olivia pretended to go along. After Lisa left, Olivia berated Johnny for thinking she wasn't smart enough to figure out he'd been shot and for not trusting her. She wondered why he tried so hard to hurt her. Johnny claimed he wanted to give her a reason to walk away from him and the violence. Olivia replied that he wouldn't live long enough to see how good they could have been together. She returned her keys and left.
Shortly after the break-up, Olivia started dating Steve Webber. Their relationship deepened after Olivia was critically injured in a bus crash. Olivia was one of the last victims to be found and suffered from severe internal injuries. Steve stayed with her until help arrived, and they grew closer while he monitored her recovery at General Hospital.
Olivia and Steve became lovers and she accompanied him to a private party on a chartered boat with a few of Steve's friends from the hospital. At some point during the night, Lisa Niles boarded the boat and had several run-ins with the guests and crew. By the time the police arrived, Lisa had disappeared but her body turned up dead and an investigation was launched regarding her murder. Both Steve and Olivia were questioned about their time on the boat until the case was closed after someone else confessed to the crime.
Since Olivia's relationship with Steve was in a good place, she turned her focus to helping Dante navigate his relationship with Lulu Spencer. Olivia encouraged her son to follow his heart with Lulu and she helped him plan his proposal. Before Lulu had a chance to respond to the proposal, Dante was shot at Sonny's warehouse and Lulu and Olivia feared for his life. Dante pulled through and Olivia credited Lulu with giving her son a reason to live by accepting his proposal.
After Dante's shooting, the war between Johnny and Sonny escalated and Olivia tried to mediate between the two warring parties. She sensed that Sonny was heading down a path of destruction and she asked her cousin Kate to reach out to Sonny before he went too far. Kate agreed and she and Sonny started dating again.
The news of the engagement between Lulu and Dante eventually became public knowledge, although Lulu was hesitant to make any plans for the wedding. Instead, Dante and Lulu decided to throw together an impromptu wedding in New York over Christmas. Olivia was thrilled about the nuptials and threw together a private ceremony for the couple. Although she had promised to keep the ceremony private, she opened the church doors as Dante and Lulu were pronounced man and wife and the Falconeri family flooded in.
Once Dante's relationship with Lulu was solidified, Olivia focused on her relationship with Steve and the issue of Maggie, his ex-girlfriend from Memphis. Maggie and Steve had been involved when they worked at the hospital together in Memphis and Maggie had taken a position at General Hospital a few months prior. Maggie openly flirted with Steve in front of Olivia and often found reasons to be with Steve at work. Olivia warned Maggie to stay away from Steve although he maintained that Maggie was his past and that Olivia was the only one he wanted to be with.
Olivia was concerned about Maggie's intentions and Johnny played into her doubts after he made comments that Steve was not as perfect and she believed him to be. Olivia confronted Steve about Johnny's comments and his relationship with Maggie. When Steve realized that he could lose Olivia, he confessed that he and Maggie had intentionally killed a patient in Memphis. The patient was a prison inmate and his heart was a match for a young patient of Maggie's in need of a transplant. Somehow Johnny learned what Steve had done and was holding the information over him. Although Olivia was horrified by what Steve had done, she vowed to help Steve get out from under Johnny's power.
While Steve and Olivia continued to deal with Johnny and his blackmail, Steve reconnected with his mother Heather. The two women were introduced and Steve asked Olivia to give his mother a chance. Heather disapproved of Olivia and warned her to stay away from Steve. Olivia doubted Heather's mental stability and she encouraged Steve to keep a close watch over his mother since she was released into his care.
The task of keeping an eye on Heather quickly fell to Olivia after Steve was arrested for the death of the patient in Memphis.. Both women were relieved when the charges against Steve were dropped after Maggie confessed to the crime via a suicide note but they continued to battle one another for Steve's attention. As time passed, Olivia grew more frustrated with Heather's comments and antics and she caught Heather in a lie regarding her whereabouts during a severe storm. Olivia realized Heather was hiding something and she hired Spinelli to uncover her secrets.
Meanwhile, Olivia learned why she and her cousin Kate had often bickered over the past few months. Kate admitted that she suffered from Dissociative Identity Disorder (DID) and that some of the heated encounters Olivia had shared with her cousin actually occurred with Kate's alternate personality Connie. Olivia stood by her cousin and she was saddened when she learned that Kate's DID was triggered after Kate had become pregnant as a teenager after being a victim of rape.
As Kate and Olivia repaired their relationship, Olivia's relationship with Steve continued to be strained by Heather's presence. The distance between them widened after Heather realized that she was being followed and accused Olivia of having her investigated. Olivia admitted that it was true and she was angered when Steve sided with his mother and admonished Olivia for her actions. Olivia tried to support Steve's belief in his mother but Olivia was unable to shake her doubts while Steve refused to believe that his mother was involved in any wrongdoing and he ended his relationship with Olivia.
Olivia refused to ignore her instincts that Heather was mentally unstable and her suspicions were reinforced after she saw a known forger leaving Steve's apartment and she caught Heather posing as maid inside police commissioner Anna Devane's room at the Metro Court. Olivia confronted Heather and warned her that the police were onto her. While Olivia tried to contain Heather until the police arrived, Heather injected her with a syringe of LSD.
The LSD caused Olivia to experience hallucinations and she and Steve worried that she would never make a full recovery. Her hallucinations gained notoriety after several events that she hallucinated came true and were viewed by some as premonitions. Despite her ability to see future events, Steve was able to surprise her when he proposed marriage and she accepted.