Ryan McNeil arrived in Genoa City, a young man in his twenties. He began working in the mailroom of Newman Enterprises, hoping to work his way up in the company. His only mention of family was an alcoholic father who had him swearing off alcohol until he moved to Genoa City.

Victoria Newman was also pursuing a career in her father's company, starting out in the mailroom, rather than attending college. Victoria was smitten by the considerably older Ryan McNeil. When Victor found out they were dating, he was rabid, and did everything within his considerable power to keep "that punk McNeil" from being involved with his precious daughter.

Meanwhile, Nina Webster began an affair with Ryan, showering him with gifts, including an expensive sports car. Victoria felt pressured to compete sexually, but her first sexual encounter with Ryan was a disaster resulting in an AIDS/pregnancy scare and a lot of sexual inhibitions. Victoria and Ryan eventually eloped, but even after marriage, Nina gave Ryan the sex life that Victoria could not. When their marriage ended, R Ryan moved in with Nina and young Phillip. Nina became pregnant, and he married her out of obligation. After Nina's miscarriage, Ryan realized he truly did love her, but he had become a devoted father to Phillip, and encouraged Nina to get her college degree. After Nina had a one night stand with her boss, novelist Cole Howard, who was married to Ryan's first wife Victoria, Cole's rejection caused Nina to suffer a nervous breakdown. She alienated Ryan, and Ryan and Nina separated.

Nina was referred to Dr. Tim Reid for help with her failing marriage. As Nina continued to see Dr. Tim, she told him how her husband Ryan was seeing a younger, prettier, thinner woman (Tricia Dennison). Dr. Tim reminded Nina to take hope in that she and her husband had been separated for months, but Ryan still had not filed for divorce. Nina gave permission for Dr. Tim to talk with Ryan, and he advised him to make every effort to win back his wife and ask her to stop working for Cole, the man who had originally come between them. Ryan decided to move back in with Nina and her son Phillip (who was later-in-life known as Chance) for a trial month, and told Tricia that their relationship was over. Although happy to be back with Phillip, whom he considered his own son, Ryan was unable to dredge up any feelings for Nina. At Dr. Tim's suggestion, Nina hired a personal trainer and began to lose weight. The evening of their wedding anniversary Nina got dolled up and she and Phillip welcomed Ryan home with a cake and fancy dinner. Phillip urged them to reminisce about how they met and fell in love, and to dance together. Ryan got back some of "that loving feeling" and kissed Nina as they danced.

After an altercation with Nina, Tricia decided to win Ryan back by making him jealous in seeing her with someone else, and it worked. Nina tried to seduce Ryan, but at the last minute Ryan stopped her, saying he couldn't do it, as thoughts of Tricia swirled in his head. Nina burst into tears, guessing correctly that Tricia was the problem, and told him to pack his bags and go to Tricia. She woke up the next morning to find Ryan sleeping on the couch. But after finding out that Nina let Tricia believe that they had had a torrid night of lovemaking, Ryan tearfully left Nina. Due to the interference of Jill and Tricia's father, Keith, trying to keep them apart, Tricia and Ryan were pushed back together, they declared their love, and Ryan vowed to get a divorce. Young Phillip saw them together, so Nina found out and disappeared.

While Ryan flew to St. Louis to ID a body who might have been Nina, Nina returned home to find Tricia staying at her apartment. Nina screamed at Tricia that she had ruined her marriage, pulled a gun out of her purse and was pointing it at Tricia when Ryan arrived home. Ryan got a hysterical Tricia to leave and tried to convince Nina to give him the gun, that he still loved her, and that they could still work it out. But instead Nina put the gun to head, saying that she had nothing to live for. Ryan lunged at Nina, and the gun went off shooting Nina in the spine. After surgery Nina woke up not remembering the incident, and Ryan was arrested for her attempted murder. But after Nina remembered, Ryan was set free. Hearing about Nina's attempted suicide did not help Dr. Tim's already low self esteem, but he helped Nina recover and become a stronger woman who ended up shocking Ryan by filing for their divorce herself.

By that time, Ryan had worked his way up at Newman Enterprises to working for Jill Abbott on the Men's Line. He later went to work for ex-wife Victoria at Brash & Sassy, and became friends with Neil Winters. Victor began to see he was wrong about Ryan; in business, anyway. Ryan failed an attempt to be Victor's mole after Brad Carlton and Jack Abbott took over Newman Enterprises, and they fired him. After Jack and Brad got Jabot away from Newman, and they and Jill left to resume working for Jabot, Ryan was hired back, and became Victor's right-hand man as assistant to the founder.

Even though Cole Howard and Victoria married, and he helped her get over her sexual inhibitions, Victoria always wondered what might have been with Ryan. Vickie ruined her marriage to Cole by her continual come-ons to Ryan, and her habit of running away from her problems, and they were divorced.

After Nina asked Ryan for a divorce, he was free to pursue the relationship with the much younger Tricia. They eventually married despite the objections of Tricia's father, Keith, and her sister, Megan. Everything seemed fine for Ryan and his child bride, except that Tricia didn't like the time and attention Ryan still devoted to Nina's son Phillip, whom he thought of as his own and whom he had adopted during his marriage to Nina. In desperation to divert Ryan's attention away from Phillip, Tricia stopped taking her birth control pills, unbeknownst to Ryan, and became pregnant. At first Ryan was upset because the timing wasn't right, but later he warmed to the idea of being a father. But Tricia miscarried, believing that it was because she deceived her husband to begin with. She had a breakdown, then rejected her husband in every way. Instead, her attention focused on her sister Megan and her relationship with Tony Viscardi. Tricia became so obsessed with her vendetta against Tony that they ended up in a physical fight in the lobby of the Colonnade Room on New Year's Eve. Tricia suddenly quit struggling and kissed Tony. It was all he could do to get her off him, confirming that Tricia had gone over the edge.

Tony decided the only solution was to marry Meg quickly. But the groom never arrived at the Justice of the Peace. Tony was run down on his motorcycle by Tricia McNeil as she blindly backed her SUV out of the Dennison driveway in a rush to stop the wedding. Tony and Megan were later married in the hospital on Tony's deathbed.

No one was able to prove that Tricia intentionally ran down Tony, and it remained a mystery. Once Megan found out that Tricia was responsible for Tony's death, she refused to forgive her and left town. Tricia left Ryan and returned to London with her father, Keith.

Tricia returned to Genoa City about six months later, hoping to resume her marriage, but Ryan was convinced that Tricia was unstable, and Victoria was once again chasing after him. Unable to win him back, Tricia turned to Carter Mills, who was really rapist Matt Clark after plastic surgery. Carter drugged her into sleeping with him, and used her to help set up Nick Newman and put him in jail. Once Tricia figured out she had been used and abused, she turned on the gas in a suicide attempt. Ryan managed to find and rescue her, only to be knocked unconscious by Carter and locked in a closet to die with gas filling the room. Ryan was rescued, but Tricia was missing. Tricia later caught Carter attempting to rape Nick's wife, Sharon, and drove off a cliff expecting to kill them both. Tricia survived with cuts and bruises, but the evil Carter/Matt deliberately pulled out his breathing tube, committing suicide to make Nick look like a murderer.

Ryan and Keith talked Tricia into institutionalizing herself at Fairhaven, outside Genoa City. She appeared to be making a miraculous recovery, signed divorce papers from Ryan to prove it, and checked herself out under the custody of her father. But behind his back she was not taking her medication, and brought Carter/Matt back from the dead as a figment of her imagination. Together they plotted revenge against the Newmans. Tricia was obviously crazier and more dangerous than ever.

Meanwhile Victoria and Ryan found their love again, moved in together, and were thinking about marriage. Victor was suspicious of Tricia, so bought their apartment building, installed security, and when her father Keith became incapacitated with a stroke, Victor even ended up with Tricia living with him to monitor her meds and protect his daughter from her. But Tricia was able to fool her therapist and Victor, faked taking her meds, and seeking revenge, drugged his tea with Rhohypnol and erectile dysfunction medication, and basically raped him. Then she beat herself up to further frame him, and Victor was arrested for rape. Paul combed the Penthouse surveillance tapes expecting to prove that Victor was setup, but apparently Tricia knew about the cameras and arranged everything out of their view, then walking into them disheveled and distraught, supposedly post-rape. DNA tests on Tricia and Victor further proved her case, but once Victor realized he'd been drugged, the same DNA sample proved he had been, and he was released on bail.

Meanwhile Tricia disappeared, leading everyone believe she was on a train to L.A., then bought a gown identical to Victoria's, locked her in a closet, and marched down the aisle to Ryan on their wedding day. Before they took their vows, the delusional Tricia lifted the veil expecting Ryan to marry her instead. Tricia pulled a gun when she realized no one in that church was anything but aghast to see her. Victor arrived in time to free Victoria, and bargained with Tricia to get everyone else out of the church. But all came to a screeching halt when Victoria entered the room. Tricia fired at her and Ryan jumped between them, taking the bullets for Victoria. Ryan held on for a few days, but died in the arms of Victoria. Tricia was institutionalized shortly afterward and the figment of Matt bade her farewell, and the rape charges were dropped against Victor.