Mark was Donna Logan's boyfriend. He pushed Donna to move in with him before they were really ready to live together. Donna soon began lying to her family and breaking promises. Everything came to a head when Donna blew off a trip to see her grandmother, which resulted in Helen being robbed of her social security check, and created problems between Donna and her siblings. Donna's family soon recognized that Mark was bad for her, even though Donna continued to stay with him. Mark got particularly jealous of the time that Donna spent with her friend Rocco (who got Donna a job at the hamburger joint, Griffey's), even though Rocco was dating Donna's sister Katie. Like many others, Mark realized that Rocco wanted to be with Donna. It didn't help that Mark always skipped the family functions, at which Rocco and Donna would always be thrown together.
Mark pushed Donna to ask Rocco for enough money to cover the rent because he didn't have a job and the two jobs she worked didn't always cover the bills. Donna didn't like the idea, but Mark told her about his terrible childhood and she gave in, not realizing how much of Mark's motivation was rooted in his jealousy of Rocco. When Donna revealed to Mark that she thought she was pregnant, Mark was furious. Donna turned out not to be expecting. While they were still together, Donna took modeling work in addition to her other jobs. She arrived home one day to find Mark in bed with another woman and, after a huge fight, she told him to get out. Mark begged for another chance, but she was done with him. Mark has not been seen since.