Megan is the younger daughter of Keith Dennison and younger sister of Tricia Dennison McNeil. Megan was a college student, who then got an apprenticeship at the Genoa City Chronicle.

Megan was a sweet and innocent person who had no clue of what went on around her. Megan was involved with Alec Moretti for quite some time, but he just didn't do it for her. Because she cared about him, but knew they had no future, she ended the relationship.

Megan met Tony Viscardi at Crimson Lights Coffee House, and was intrigued by his great looks, and "bad boy" image. Even after Tony told her that he was no good for her, she wouldn't give up on her pursuit of this motorcycle-riding auto mechanic; a far cry from Megan's sheltered little rich girl background. Both Megan's father, Keith, and sister, Tricia, did not approve of their relationship and made that very clear to them. They did not make life easy for the two lovebirds, feeling that Tony came from the wrong side of the tracks. Megan insisted that she didn't care what they said. She was in love with Tony, and he was the only one for her despite what her family wanted.

A few months into their relationship Tony's boss set him up to drive stolen cars from Florida to Genoa City. On a trip back from Florida, unknown to Tony and Megan, they were driving a stolen vehicle and were arrested. They got off on all charges because Tony pleaded with the Assistant D.A., Glenn Richards, to get Megan off. Sounding sincere, Richards bought Tony's plea, which Megan found out about later. She was even more thrilled that he had done that for her. Megan's father was upset when he found out, but Megan calmed her daddy down.

Tony didn't think Meg was right to defy her family, so stayed with ex-lover Grace who bailed him out of jail and gave him a roof over his head. Megan wouldn't forget him. She made Tony admit his feelings for her, and he finally told her that he loved her. The two were a hot item after that. Then one day Grace was fired from Newman Enterprises. There was no Nick to obsess over, so she wanted Tony back and tried to seduce him. Tony wouldn't allow it, and backed off by moving into his old place, which was still available.

Before he returned to London, Megan's father asked Tricia to separate the Megan and Tony. Both agreed Tony was not right for Megan. Tricia teamed up with Grace Turner to try to make it happen. But their attempt failed.

Megan blindly believed that Tricia was accepting Tony, but he knew better. The tension between Tony and Tricia was obvious to everyone but Megan. Tricia became so obsessed with her vendetta against Tony they ended up in a physical fight in the lobby of the Colonnade Room on New Years Eve. Tricia suddenly quit struggling and kissed Tony. It was all he could do to get her off of him. It was then that we knew that Tricia had gone over the edge.

Tony decided the only solution was to marry Megan quickly. The wedding was arranged at the justice of the peace, with Nina Webster standing up for Megan, Sharon Newman for Tony, and Cassie Newman as flower girl. But the groom never arrived. Tony was run down on his motorcycle by Tricia McNeil as she blindly backed 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. Poor Megan. She lost her true love by her own sister's hand. Shortly afterward, Megan left town, unable to forgive what her sister had done to her beloved Tony.

In July of 2001 Tricia and Keith traveled to Megan's graduation from Boston University. Megan spent a lot of time in Europe before returning to Boston to make her home. Since then Keith went into a coma, and Tricia went insane, killed her husband, Ryan, and was institutionalized.