1994-2002
In the pilot episode, which takes place on St. Patrick's Day 1994, Dr. Greene is awakened in the first scene to help sober up his long-time friend Doug, the ER resident often comes in to sober up on his nights off. Also the friendship between him and Susan is shown to be close as the two confide in each other about their personal lives while on break. Within the same episode, Jen gets Mark to visit a private practice near the hospital to explore the possibility of leaving his job at the ER, to give him more family-friendly hours. Mark decides the "clean" medicine isn't his cup of tea. Back at the ER, Mark removes a hangnail from an older woman, who wanted him to remove it despite the fact she'd be charged $180. Later during the night, Mark has to urge everyone to get back to work when Carol is rushed into the ER, after a shocking suicide attempt.
During the first season, Dr. Greene's marriage becomes increasingly shaky. When offered an attending physician's position by David Morgenstern, Mark readily accepts, much to Jen's chagrin. As a newly admitted member of the bar, Jen has been clerking in Milwaukee for a judge and becomes increasingly tired of commuting and living separately to accommodate Mark's job. She begins an affair with a coworker, and the marriage soon ends, with Rachel and Jen leaving Chicago first for Milwaukee, and later for St. Louis.
In "Love's Labor Lost", Mark made miscalculations in treating a pregnant woman that led to her death in childbirth, and the after-effects of this case lingered long into Season 2.
In "A Miracle Happens Here", a Christmas episode, Mark explains that he is the son of an agnostic Jew and a lapsed Catholic. He lights a Hanukkah candle for a Holocaust survivor. Mark understands some Yiddish.
Mark's career becomes more difficult as he begins needing to make decisions that periodically alienate his friends, such as selecting Dr. Kerry Weaver over another applicant, which angered Susan Lewis first because the other applicant was a good friend of hers, and later because she bristled under Kerry's demanding, sometimes harsh leadership style. His friendship with Dr. Ross becomes strained as his administrative tasks often put him at odds with Doug's wild ways and he was disgusted by Doug's personal problems to the point where he briefly overruled and belittled Doug's abilities as a physician, then reconciled with his friend. His love life took a more drastic downward spin when his feelings for Dr. Lewis became so noticed that he's driven to ask her out, only to have her leave for Phoenix, Arizona. He suffers emotionally again after he is attacked in the ER men's room in the episode "Random Acts", initially believed to be a retaliatory act to avenge the death of a patient who may have been "mistreated" by Dr. Greene because of the patient's race. Later on, though, it was strongly implied that his assailant was a psychotic individual who was randomly attacking doctors. Mark bought a gun and later used it to scare away a crowd of punks on a train, but decided to toss the gun in the river soon afterwards. He would struggle through a large part of Season 4, but came to terms with it in Season 5 when he helped Nigerian-born janitor Mobilage Ekabo reveal his memories of torture by talking about the attack with him, allowing him to obtain political asylum and avoid deportation.
With the passing of Doug's father comes the re-entrance of Mark's parents. He and Doug travel to California to settle Doug's father's affairs (Doug's father and new wife were both killed in a car wreck) and take a side trip to visit Mark's parents, who live in another part of California. His relationship with his father David is still strained, and his mother suffers from a string of medical conditions associated with aging. Mark also finds out that his mother viewed his birth as a mistake, as she didn't know his father well and had to get married quickly when she got pregnant. Mark's distrust of the Navy puts him at odds with David when he and Mark fight over whether Ruth should be treated in a base hospital or a civilian hospital. Ruth eventually dies and Mark goes to her funeral, leaving him on edge when he clashes with Kerry Weaver over Robert Romano's successful drive for the chief of staff position.
Mark's personal life after his marriage is tumultuous. He takes after Doug, having several flings and an affair with Nurse Chuny Marquez, and even setting up three dates in one day. He has a brief relationship with a needy desk clerk, Cynthia Hooper (played by Mariska Hargitay in season 4). Hooper leaves him after she finds out Mark doesn't really love her. Mark eventually meets a British surgeon, Elizabeth Corday. Corday is in Chicago on an exchange program, under the guidance of Dr. Romano. Romano's advances on Corday fail, as does her relationship with Peter Benton. Eventually, Mark and Elizabeth begin dating. Mark discovers that his father is suffering from advanced lung cancer. After David loses his wife and develops end stage lung cancer, he realises that he can no longer live alone, and he moves to Chicago and stays with Mark. After an emotional bonding that healed their difficult relationship from Mark's youth, David dies.
Mark and Elizabeth begin a more serious relationship and move in together. Mark later buys a house, and Elizabeth and he are married. Together they have one daughter, Ella. Their happiness is threatened, though, when the abusive father of a patient goes on a killing rampage after losing his son to social workers. In a bid to get his son back, he kills and injures a number of people and even attempts to go after Elizabeth and Ella. After being shot by an armed bystander, he is brought to the ER. During his treatment, he is being transferred by Mark to the operating room when he goes into arrest. Alone in the elevator, Mark decides to withhold defibrillation and allows him to go into vfib and die. He later falsifies records to show that he did attempt to save him. Elizabeth suspects what Mark did but lets the matter drop without any further discussion. Later, Rachel appears in Chicago unannounced, citing arguments with her mother, and moves in with Mark and a very reluctant Elizabeth. She is found to be sneaking out of the house at night and using drugs, which clouds her relationship with her stepmother, Elizabeth.
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