Jacqueline Peyton was an emergency room nurse at All Saints Hospital in New York City.
It was revealed early in the series that Jackie has been battling a prescription drug problem and has been having an affair on her husband Kevin Peyton with the hospital pharmacist Eddie Walzer. Along the way, Jackie must deal with the overly flirtatious behavior of emergency room doctor, Dr. Fitch "Coop" Cooper, played by actor Peter Facinelli. At the hospital, Jackie uses her romantic relationship with Eddie to have ready access to drugs.
Jackie reveals during rehab that her addiction began shortly after her eldest daughter, Grace, was born. She told her friend in rehab that "I stole a hundred Percocets... and never looked back". She didn't go into detail, but said her daughter's incessant crying "made me wonder... is she on to something?"
She is known at All Saints' for being a tough, skillful nurse and taking extremely good care of her patients, even when that requires going outside the confines of the law. Committed to helping her patients, she often finds and points out mistakes made by the doctors during patient visits. She is an excellent liar, and uses her grey sense of morality for the betterment of patients.
Kevin is her husband for the first three seasons of the series, but after it is revealed that Jackie has a prescription drug problem that she claims to gotten help from rehab to resolve her drug addiction. Kevin has a affair because of Jackie ignoring him and claims things were "so bad" at home and lonely. Jackie soon after said "pack your bags" and they get a divorce into the following season. Kevin sues for full custody because of Jackie's "crazy schedule hours" at All Saints. Kevin also asks for Psychiatric testing but gets blown away when Jackie asks Fiona to draw a picture of their life at that moment Jackie,Grace, and Fiona are close together in child-like picture when Kevin is on the opposite side in his "own life".
Kevin and Jackie have a rocky relationship for the rest of the series.
They were married for 16 years and met in high school.
Eddie is Jackie's secret affair. Through the first season Jackie is shown to be almost just using Eddie and his romantic feelings towards her to get her prescription drugs. Over the series, after he finds out that she is married, he still has romantic feelings towards her that she does not feel for him. Over time, though, they begin to form a close friendship as he helps her deal through her addiction and tries to help her through the custody battle with Kevin. When she has her nursing license suspended, he aids her in illicit activity to raise the money for a lawyer.
Eddie and Jackie get engaged after she gets her nursing license back.
The elder of her two daughters, Jackie and Grace are often at odds with each other. As a young girl and teenager, Grace suffers from an anxiety disorder. Jackie and Kevin take her to a theprist soon after a incident at school Grace gets a prescription of Xanax at a low dose, Jackie lets her take her first dose then Jackie swallows the whole Xanax bottle then asks Dr. O'Hara for refill to cover up her mistake. Grace as she gets older she meets a 18 year old guitar player at the age of 14. Grace and her boyfriend both have a scene of snorting Adderall, but then later gets caught by Kevin of Grace having a huge bag of Adderall capsules that she claims that is Jackie's, but isn't she later confesses. Grace and Jackie get blood tests when Jackie is clean, when Grace has a high amount of Adderall in her blood. Grace finally accepts her mom Jackie as she is as she grows older to understanding Jackie addiction is a disease.
Her younger daughter, Fiona, is a much more laid back child and is easier to deal with than Grace. As Fiona grows older, she tends to regress to behavior belonging to that of a young child. Jackie once describes Fiona acting like a three-year old. Fiona’s child like behavior may be attributed to the time Kevin and Jackie spent handling Grace's anxiety disorder.