David Stewart relocated to Oakdale from New York with his wife, Betty and sons after landing a job as Head of Research at Memorial Hospital. A bright and personable man, David quickly made friends with the folks of Oakdale, among those was Ellen Cole, the stepdaughter of Memorial's Chief of Staff. Not long after, the Stewarts were shocked to discover that Ellen was actually the biological mother of their adopted son, Danny! Though Betty wanted to leave town immediately with the boys, David disagreed and convinced her that they should stay. The Stewarts remained in town and, when Ellen fought for custody of Danny, they fought to retain custody. Though the court allowed Danny to remain with the Stewarts, Betty decided that she couldn't stay in the same town and left with the boys while David continued to work in Oakdale.

Sadly, a few years later, Betty died of double pneumonia, leaving David to raise his sons alone. Bringing the boys to town, David tried to make a life for himself as a single father. Of great comfort during this time was Ellen, who felt guilty about her actions years earlier. Over time, their friendship changed into love and, despite resistance from Dan, the pair married. Soon after, Ellen would give birth to two daughters, Carol Ann (Annie) and Dawn (Dee).

For the next two decades the Stewarts' marriage would remain on solid ground. During this time, David helped his children though their professional and romantic crisis and became close friends to Bob Hughes. Through the years, David would remain a steadfast and levelheaded influence on those around him. That was until John Dixon began dating his youngest daughter, Dee. Hating John for the pain he'd caused Dan (who was since dead), David raged against the match and vowed to stop their impending wedding. After losing his temper several times with John, David realized that he was in danger of losing his daughter and reluctantly gave his blessing. Unfortunately, the marriage was not a happy one and when David found Dee crying one morning saying that John forced himself on her, he'd assumed she'd been raped and helped her file charges against him. Unfortunately, things didn't go as David thought they would with the trial ending with John being exonerated and Annie losing the child she was carrying. His anger at John overpowering him, David quickly left town because he was afraid he'd do something drastic if he stayed. Gone for months, David was found by none other than John Dixon! Suffering from amnesia as a result of the stress he'd been under, David had made a life for himself out of Oakdale (as Donald Saunders) and even made plans to marry another woman by the name of Cynthia Haines. When his memory was finally restored, David and Ellen had a rough time putting their marriage back together since he was uncertain about which woman he loved. In the end though, his love for Ellen prevailed and the two remarried in a beautiful ceremony.

David and Ellen's marriage remained stable after that and he spent the next several years helping his granddaughters sort out their love lives. In 1985, David left Oakdale to conduct AIDS research in Zaire. In May 1986, David returned to Oakdale and decided to continue his research in Switzerland. That same year, David returned to Oakdale to attend Chris Hughes's memorial service and left for Chicago to conduct his research. David Stewart flew to Greece to help his granddaughter, Betsy, in 1987. On New Year's weekend 1988, Ellen took a trip to London for a few weeks to be with David. The same year, David returned for a visit and was shocked to learn that Betsy was dating a rapist. That same year, he also attended Nancy Hughes's wedding to Dan McClosky. In 1989, David returned and asked Ellen to join him in Africa. Although she had missed him terribly, Ellen refused to go, stating that Oakdale was her home. Wanting to continue his work and be near Ellen, David compromised and continued his research in Atlanta, Georgia where Ellen could visit him on weekends. David died of a heart attack in Atlanta in 1991.