Carol Hathaway

Eight weeks after her suicide attempt, Carol returns to work. Although she later denies it, the staff suspects that her suicide attempt was brought about by her failed romance with Doug Ross, a womanizing pediatrician also working in the ER. Carol explains in the episode, Going Home, that the attempt was actually caused by “things piling up” and feeling trapped.

In 2021, actress Julianna Margulies recalled her character's first episode. She said, "Whenever my character was at the medicine cabinet getting meds for her patients, she was putting some in her pocket for herself [for her eventual suicide attempt]. Not that they ever paid attention to that. If you re-watch the pilot, you can probably see her pocketing some medication." [2]

In the episode, Long Days Journey, Carol helps work to save a woman who does die by suicide in the ER. After the experience, Haleh tells Carol that she knows that must have been hard for her to relive. Haleh asks if Carol had written a suicide note like the woman they had worked on. Carol replies, “No. I didn’t know what to say.”

Carol keeps Doug at a distance in both professional and private matters, which becomes difficult as Doug continually tries to win her back, on one such occasion showing up drunk on her doorstep, with flowers. While Carol harbors animosity towards the brash pediatrician, it becomes obvious to the viewer as well as the staff, that there are continuing feelings for him.

In an attempt to move on from her fractured relationship, Carol becomes engaged to orthopedic surgeon John "Tag" Taglieri (Rick Rossovich). The relationship is tumultuous from the start, since Carol cannot commit fully to Tag, and against his wishes, she tries unsuccessfully to adopt a Russian child suffering from AIDS that was abandoned in the ER. She is denied because of her past suicide attempt.

Right before they are about to walk down the aisle, Tag leaves her at the altar, telling her he cannot commit to someone who cannot reciprocate those feelings. While Carol is hurt, the ER staff attempt to cheer her up and help her feel better at the wedding reception, with food, drinks and music.

Carol, in an attempt to become more independent, purchases a run-down row house, which she plans on renovating. She later becomes involved with paramedic Ray "Shep" Shepard (Ron Eldard), who moves in with her.

In season 2, episode 8, Carol cares for another patient who has attempted suicide. While working on the girl, she comments to Mark that she “hates this” and is clearly affected by the patient, to whom she later shares the story of her own attempt a year before. After caring for the patient, Shep comments - unaware of Carol's history - that anyone who takes a bunch of pills just wants attention and doesn't really mean it. Annoyed, Carol replied, “I really meant it,” shocking him and leading him to try to apologize to her several times. Later, he told her that he was glad that her suicide attempt had failed. Carol answered, “Me too.”

Despite a promising start, their relationship becomes severely strained after Shep goes through a drastic personality change after the death of his work partner. Shep and his partner had decided to enter a burning building to save children who were trapped by the fire. Shep's partner was badly burned and later died in the ICU. Shep becomes abrasive, and despite Carol's attempts to get him professional help, he refuses, so she ends their relationship, refusing to watch someone she cares about self-destruct.

Without Shep's extra income she is unable to afford her house. Things get even worse when a labor dispute arises concerning the reassignment of her nurses. As nurse manager for the ER, Carol is privy to management decisions, and she finds herself torn between her friends and the hospital administration. During a nurse sickout, Carol accidentally transfuses the wrong blood into a patient. Although it is unclear whether it was the blood or his other injuries that cause his death, Carol blames herself. The administration initially does not punish Carol for this incident and uses it to cast the sickout in a bad light, but she resents the administration's actions and believes she is not being punished sufficiently for her error, so she talks to the press and gets suspended.

During her suspension, Carol is held hostage at gunpoint during an armed robbery at her local grocery store. She treats several injured people and performs advanced procedures, including a tracheotomy, using only the supplies in the store. She manages to escape the incident, shaken but unharmed.

Carol is shown taking pre-med classes at a local college, and later takes the MCAT with Doug's encouragement. She assumes she failed, when in fact she did very well. She scores in the 85th percentile, impressing the hospital and leading Kerry to take her under her wing. However, she opts not to pursue medical school, having only taken the test to prove she was capable. Carol opens up a free clinic in the ER, backed financially by colleague Dr. John Carter's wealthy grandmother. The clinic is a success, helping many in the community.

It was also during this time that Carol and Doug become closer again as friends. Doug, the once-womanizing pediatrician, hits rock bottom, leading a life of celibacy after one of his one-night stands dies from a cocaine overdose. As he straightens out his life, Carol begins to see him differently, and after a surprise passionate kiss on her doorstep, Doug and Carol begin to rekindle their relationship.

Their relationship is held up by Carol's insecurities and bitter memories of the past. Frightened over what the staff might think, Carol and Doug romance each other in secret, even though it is obvious to the staff, who start an office pool over when they will out themselves. Doug's attempts to make up for his past mistakes and commit to her eventually pushes her back.

In season 4, after an intense paramedic ride-along involving a suicide, Carol opens up to a paramedic, Greg, about her own previous suicide attempt. Greg's mother had killed herself when he was a child, and he expressed his belief that his mother had only been thinking of herself. Carol told him, “I thought of everybody but me when I tried to kill myself.” The two then shared a deep conversation with Carol continuing, “I just got wrapped up in everyone else’s expectations of me. I forgot who I was. Now, I’m okay. I even tried to go to med school, but it just wasn’t for me.” As their conversation continued, the two suddenly kissed. Later, horrified at her actions, she confesses to Doug, who leaves her for a while.

The two eventually reconcile. Carol overcomes her insecurities and is finally able to put those demons to rest and commit fully to Doug. Soon after, the two decide to conceive a child.

Doug's constant run-ins with authority begin to jeopardize not only his job, but also his relationship with Carol, who despite her devotion finds it increasingly hard to support his reckless decisions regarding patient care. This all comes to a head when a terminally ill boy dies under his care. Using a PCA machine from Carol's clinic, Doug authorizes the mother, Joi, to administer enough pain medication to stop his heart. An ensuing scandal resulting from the police investigation ruins both their careers. Carol is forced to give up control of her clinic and Doug is forbidden from seeing patients. Seeing no other way out, Doug resigns, leaving for Seattle to take a lucrative job offer despite Carol's protests. Unbeknownst to Doug, Carol is pregnant with twins.

Carol delivers Tess and Kate Ross on Thanksgiving Day assisted by then-OB nurse Abby Lockhart with long-time friend and colleague Dr. Mark Greene as her birthing coach. When Doug learns of his twin daughters' birth via a telephone call, he invites them to come and live with him in Seattle. Carol cannot decide if it is the right thing to do; still hurt over his abrupt departure a year earlier, she attempts to raise their daughters alone. Dr. Luka Kovač, a new Attending from Croatia who lost his wife and children in the Croatian War of Independence, often helps her take care of the twins, and a tentative romance eventually develops as the two become closer, but Carol doesn't see it going anywhere. Treating a woman dying of end-stage ovarian cancer and helping her family say goodbye moves Carol to reunite her own family, realizing she has been in love with Doug "since she was 23 years old." After apologetically saying goodbye to Luka, she abruptly leaves work and flies to Seattle that day to reunite with Doug. It is later revealed that the day she left Chicago, Carol sent for her twin daughters to join her and Doug in Seattle.