Molly Lansing was born in the Glencoe tunnel following a horrific train wreck. Alexis Davis and Ric Lansing named their daughter Molly after the Titanic survivor, the Unsinkable Molly Brown. Before Molly was born, Ric and Alexis had contemplated divorce, but the birth of their daughter convinced them to try to make a go of their marriage.

In 2006, Alexis discovered the identity of the daughter she had given up for adoption, and Molly met her new big sister, Sam McCall. After Alexis spied Ric and Sam making love, Alexis and Ric split. A short time later, Alexis revealed that she'd been diagnosed with lung cancer. Ric discovered that she had smoked marijuana to ease the pain, and he used it as a ploy to prove Alexis was an unfit mother.

Ric successfully sued for custody of Molly. When Ric's father, Trevor Lansing objected to his son using Molly as a pawn. He threatened to take Molly away from Ric, prompting Ric to let Molly live with her mother. Eventually Ric and Alexis agreed to joint custody. In 2009, Ric moved to Los Angeles and left Molly in Port Charles with Alexis.

Molly was an excellent student and an incurable romantic, so romance novels were high on her list. Molly took great pleasure in planning special romantic dinners and dates for Sam and Sam's boyfriend, Jason Morgan. Along with her sisters, Kristina Corinthos-Davis and Sam, Molly tried to play matchmaker between Alexis and Mac Scorpio. Mac was a surprise guest for Thanksgiving dinner and Christmas, and Molly was thrilled when she saw Alexis and Mac kissing under the mistletoe. Alexis was onto Molly's scheme, but she genuinely liked Mac so she wasn't angry.

A precocious pre-teen, Molly was known for her excellent pitching arm. At the General Hospital carnival, she successfully dunked every guy in the "Dunk-a-Hunk" contest. However, Molly was very upset when it was revealed that Alexis had had an affair with Mayor Floyd. Things got worse when she heard gossip about her mother at school and discovered unflattering postings about Alexis online. When Alexis found out, she prohibited Molly from using the computer.

In 2010, Molly discovered that her cousin, Michael, was a suspect in a hit-and-run involving Claudia Zacchara. When Michael fled Port Charles to avoid prosecution, Kristina went with him, leaving Molly to cover for them, but she was relieved when Sam tracked the teens down. Molly overheard Alexis confiding to her friend, attorney Diane Miller, that it had been Kristina behind the wheel and, in order to protect Kristina, Alexis intended to confess to the hit-and-run.

After Alexis was wrongfully accused of murdering Mayor Floyd's mistress, Molly went to her cousin Nikolas Cassadine for help. Nikolas was able to get Alexis' sentence reduced to community service. Alexis was upset that Molly had taken it upon herself to go to Nikolas, but Nikolas was impressed with his young cousin's maturity, and he told Alexis that she should be too. Ultimately, proof was found that it had been the mayor's wife who had killed his mistress, and she had framed Alexis.

Molly and her cousin Morgan were the same age and were very close. Molly enlisted Morgan's help collecting water samples for a science project. They were down on the docks when they heard someone yelling for help. They traced the cries to a warehouse, where Johnny Zacchara had been held hostage by thugs. Molly distracted the guards while Morgan freed Johnny. Johnny was very grateful to the kids.

Meanwhile, Kristina had been getting serious with her first boyfriend, Kiefer Bauer. Alexis and Molly liked him, but they were unaware that behind his perfect façade lurked an abusive monster. One night, Alexis arrived at home to find Kristina badly beaten and barely conscious. Alexis grabbed her daughter and raced to the hospital, unaware that she had hit Kiefer with the car as he ran in the dark from the house. Sam and Molly found Kiefer badly injured on the side of the road. He died from his injuries. When Kiefer's father, Warren Bauer, vowed revenge on Alexis and Kristina, a frightened Molly went to Jason and asked him to "make Mr. Bauer disappear." Jason explained to Molly that he couldn't.

In January 2010, it was revealed that Dominic Pirelli was really Dante Falconeri, the son of Molly's uncle Sonny Corinthos, Molly met her new cousin. Dante was a cop and took no pleasure in being Sonny's son, but he embraced being a brother to Michael, Morgan, and Kristina, and a cousin to Molly. Michael had confessed to Kristina, Morgan, and Molly that it he, not Sonny, who had killed Claudia. The siblings kept his secret, but Dante found out and told the judge.

Dante assumed that Michael would get community service because the killing had been in defense of Carly and Josslyn, but the judge threw the book at Michael for covering up the crime. Molly was upset at the betrayal, but she forgave Dante when he secured Michael's release.

In January 3, 2011, Molly was on a school ski trip when the bus that she was traveling in crashed, leaving many students, including Kristina and Morgan, injured. Molly volunteered to help Michael flag down cars for much-needed help. After the accident, Molly began to act out, and she worried that she might be bipolar. Molly researched extensively on the Internet about the disorder. She also had a heart-to-heart chat with her Uncle Sonny, who was bipolar, about the symptoms. One day, Molly heard a car crash, and she had a panic attack. Shawn Butler, an ex-Marine, saw her shaking and talked her down.

Shawn suggested that Molly might have post-traumatic stress disorder because her symptoms were similar to what he experienced. He was right, and Molly sought help in therapy.

Molly was excited to be a bridesmaid at the glamorous Brenda Barrett's wedding to her Uncle Sonny. Alexis was running late for the ceremony, and Molly volunteered to look for her mother. Molly heard Theo Hoffman enter Alexis' office, so she ducked under the desk. Molly overheard that Theo was a notorious and dreaded criminal known as "the Balkan." The Balkan had made several failed attempts on Brenda's life. Molly shared the secret with Jason and Sam. They assured Molly that they would save Brenda, but the limo that Brenda had climbed inside blew up, and Brenda was presumed dead.

Molly suffered tremendous guilt for not speaking up to others. Molly lost her faith in romance, and she vowed never to read another romance novel. Soon, it was revealed that Brenda hadn't been in the limo, but Sam had been caught in the blast. Sam temporarily lost her hearing, and with Molly's help Alexis, Kristina, and Jason learned sign language. In time, Sam regained her hearing.

Molly remained close to her sisters, and she often meddled in the lives of her loved ones especially in the name of romance. She was fiercely loyal and clever. As she grew older, she often supported the underdog.

On January 17, 2012, Shawn was surprised when T.J. Ashford turned up at the diner. T.J. was the son of Shawn's best friend -- and the man that Shawn had killed with a shot in the back. T.J.'s mother had sent her troubled son to live with Shawn, or T.J. could go to military school. T.J. enrolled in school, and Molly immediately took T.J. under her wing because she was grateful to Shawn for his help when she had been dealing with PTSD.

T.J. appreciated Molly's help with tutoring, so he offered to help her become more popular. He created an online social media account named Desdemona then invited dozens of teens to an underage drinking party at Molly's home on a night when Alexis was gone. During the party, Molly unknowingly consumed alcohol and passed out. Alexis correctly assumed T.J. had been behind the party, so Molly insisted that the party had been solely her idea. T.J. confessed because he didn't want Molly to take the blame for his mistake.

Alexis banned Molly from having any contact with T.J., but the teens ignored Alexis and began to date in secret. Eventually Alexis learned that they were together, and she demanded that they end their relationship. Shawn intervened on their behalf, and he persuaded Alexis to allow them to see one another as long as the kids followed the conditions that Alexis set.

Molly and T.J. agreed to Alexis' terms, but they feared that they were out of time because they had shown the early signs of exposure to a deadly toxin that Jerry Jacks had placed in the water supply. On August 30, they each made a bucket list of the things that they wanted to do before they died; making love appeared on each of their lists. Molly and T.J. considered making love, but they decided to wait. Molly was happy with her decision especially after she learned that the antidote to the toxin had been derived and that both she and T.J. would live.

While Molly continued to spend time with TJ, she also found time to baby-sit her new nephew, Sam's son Danny. She also wrote a book titled Love in Maine. Michael's girlfriend Starr Manning read the manuscript and convinced Molly to send the book to a publisher. The publisher that Starr had in mind was her father Todd Manning, and he agreed to take a look at Molly's work. However, before Todd had a chance to read the manuscript it was stolen by Kate Howard's alternate personality Connie Falconeri. Connie made some changes to the manuscript then claimed that she had written the book. Molly was outraged by what Connie had done, but Molly was unable to prove that she had written the manuscript.

In February 2013, Molly met a mysterious young man named Rafe Kovich Jr. He was homeless and hungry, so Molly treated him to lunch. After their lunch together, Molly was shocked to learn that Rafe had been arrested for the murder of his mother, heiress Alison Barrington. Molly visited Rafe after his arrest, and he swore that he was innocent. Rafe claimed that police officer John McBain had killed his mother. TJ disapproved of Molly's friendship with Rafe, and T.J. believed that Rafe was dangerous. Despite TJ's request, Molly continued to help Rafe. She lied to TJ when she secretly harbored Rafe in her bedroom as Rafe hid from the police. Molly also convinced her mother to help Rafe obtain legal counsel. Molly's relationship with TJ was strained when he learned that Molly had lied to him.

After the charges against Rafe were dropped, Molly remained concerned because Rafe had been placed in a group home. She begged Alexis to take him in, but Sam became Rafe's legal guardian instead. Rafe appreciated all that Molly had done for him and he kissed her. Afterwards, Molly explained to Rafe that she was with T.J. -- and that she thought of Rafe only as a friend. However, T.J. continued to disapprove of Molly's friendship with Rafe and she was offended by his jealousy. She refused to attend the prom with T.J., so he took a girl named Taylor Dubois.

Molly was devastated when she learned that T.J. had slept with Taylor, but a family crisis dominated her throughs when Sam's son was diagnosed with leukemia. Both T.J. and Rafe offered support to Molly and her family. In time, Danny received a life-saving bone marrow transplant, and Molly and T.J. resumed their relationship. Rafe took their reunion poorly. Rafe overheard T.J. admit that T.J. had witnessed a mob shoot-out. Rafe reported it to the police, which made T.J. a target of the mob. The incident forced Molly to realize that she could not trust Rafe. Her certainty was confirmed when Rafe told her mother about Molly and T.J.'s plan to spend the night in a hotel room.

While Molly pushed Rafe out of her life, she allowed her father back in when Ric Lansing returned to Port Charles in February 2014. Their reunion was short-lived, as Ric was arrested for mob activities including murder. Ric swore that he had been framed, and Molly believed in his innocence. He was taken into police custody, but Ric was killed before he had the opportunity to clear his name. Molly struggled to accept her father's death, and she believed that her mother's boyfriend Julian Jerome had falsely implicated Ric and lied about Ric's ties to the mob.

As Molly grieved for her father, she reached out to Rafe when she learned that he was using drugs. On July 3, 2014, Molly was the passenger in his car as Rafe tried to evade the police in a high speed chase. When Molly demanded to know why Rafe was trying to run from the authorities, he confessed that he had followed someone's orders and intentionally driven Patrick Drake's car off the road, which had killed Patrick's unborn son. Before Molly could question him further, their vehicle crashed into a police roadblock, and Molly was knocked unconscious. When she awoke, she asked about Rafe.

Rafe had suffered a devastating seizure. Surgery hadn't helped, and on July 16, Rafe passed away. Molly was heartbroken. Later, it was revealed that Rafe had had heroin in his system at the time of the accident. T.J. supported Molly as she grieved for her tragic young friend. T.J. and Molly continued to grow close, and they made love when the time was right for both of them. They supported each other through various ups and downs including when Ric was revealed to have been alive and in witness protection, and when T.J.'s mother arrived in Port Charles working for the Jerome crime family.

T.J. leaned heavily on Molly when it was revealed that his biological father was Shawn Butler, and that Jordan Ashford had sent her son to live with his father when she had decided to go undercover infiltrating the Jerome crime organization. T.J. was equally supportive of Molly when her mother became romantically involved then married Julian Jerome, and when Molly lost her beloved cousin, Morgan, in a car explosion.

On June 16, 2016, Molly and T.J. decided to move in together. They found an affordable apartment in the Charles Street district, across the street from Charlie's Pub, which was owned by Julian Jerome. Julian had left the mob, and his marriage to Alexis had fallen apart, but Molly had never warmed to him. However, when a developer wanted to revitalize the Charles Street District, Molly and Julian banded together with the neighborhood to fight the redevelopment plans, and the illegal tactics used to drive out the tenants.

T.J. was in medical school, and Molly was a full-time college student, so money was tight. When an earthquake rocked Port Charles, T.J. and Molly were temporarily displaced. Molly also remained close to her sisters and was there for them through all their ups and downs. She was proud when Kristina came out as bi-sexual, and she was thrilled when Sam became pregnant with her second child, a girl named Emily Scout. Molly was a doting aunt, and quick to help like when her mother decided to seek treatment for an alcohol addiction and when Sam recovered from an illness after Scout's birth.

In the spring of 2019, Molly became concerned about Kristina's connection to an organization called Dawn of Day. The organization worked through community outreach programs to improve impoverished neighborhoods, but Molly noticed that Kristina had started to pull away from family and friends because of the teachings of the charismatic leader of DOD, Shiloh. Kristina was right to be concerned because DOD was a cult, and Shiloh had made plans for Kristina. However, Sonny and Jason thwarted Shiloh's lecherous intentions by abducting Kristina then -- with the help of a psychiatrist, family, and an ex-cult member -- made Kristina realize that Shiloh was no good.

Molly was relieved that Kristina had gotten out, but her concern remained because it appeared that Sam had been sucked into the cult. Molly approached Peter August with the idea of writing a series about DOD for his newspaper, the Invader. Peter gave Molly his card and looked forward to seeing her work. Lulu Falconeri, Peter's top reporter, assured Peter that she would be happy to teach the eager young apprentice the ropes.