Kelly-Marie Maguire (née Ball) is the sister of Kevin Ball and the ex-wife of Shane Maguire. A former heroin addict, she occasionally visited the Chatsworth Estate to see her brother when she had nowhere else to go. However, her return in 2007 was permanent. She became a prostitute and began working at Lillian's brothel, becoming a superior role in the business. She gained status on the estate by marrying Shane Maguire. But the marriage ended when she fell in love with Marty Fisher. She eventually left the estate in 2013 after cutting her ties with her friends and family.
Kelly met Shane Maguire in Episode 5 of Series 5 when going to Yvonne's shop for some cigarettes. Shane was attempting to catch a loose cockroach, which Kelly caught for him without any apparent revulsion. Shane was smitten and offered to go out on a date. Kelly offered Shane to meet her at 'work' in Lillian Tyler's house. Shane quickly found out she was working as a prostitute, but still wanted to sleep with her. She told Shane that she was still on the job, prompting him to borrow money off his brother, Micky, which began a string of sexual encounters with Kelly at Lillian's. Incidentally, Shane would run up a tab due to his regular sessions with Kelly. It was not her intention to put Shane in debt to the brothel, but Paddy, who was collecting money, learned of this and gave Kelly a bribe, and a threat, to leave Chatsworth. Kelly would return several months later, Kelly would return to Chatsworth with Paddy's money and return to Shane, who, upon learning what his father had done, would confront him at The Jockey. The confrontation resulted in Shane assaulting his father, but Paddy would overpower his son and savagely beat to the ground. Kelly, Mimi and Mandy would run in to stop Paddy, who left the pub ashamed of himself. The following day, Paddy sought his son's forgiveness, and asked him to invite Kelly to dinner.
Kelly would further cement her place in the confidence of the Maguire family by retrieving Mandy's daughter Katie from from a teenager who kidnapped her, and revealing that she was pregnant. However, it was revealed to have been a phantom pregnancy by the beginning of Series 6.
In Series 7, after pulling off a series of wedding scams together, Shane unexpectedly proposes to Kelly, who is ill at ease with Shane's offer. This is due in large part to her guilt from earlier having sex with Paddy, who, feeling hurt from his sons bailing out on him during a night out on the pull, paid Kelly for sex to get revenge on his son Shane. Shane would later find out what happened, and forced his father to make it up to him by taking heroin, despite having recovered from his addiction in the previous series. As Paddy was about to put the needle in his arm, Shane relented and took the needle from Paddy. Shortly, Shane and Kelly would have an impromptu marriage ceremony performed for them at The Jockey.
As Shane and Kelly would often look after Katey, Lip and Mandy's daughter, and would also babysit Stella and look out for Liam, Shane increasingly desired children of his own, but his hopes were dashed after a visit to a fertility clinic.
Through the later series, Kelly, who was desirous of retiring from the prostitution business, encouraged Shane to rise in the family business, and was resentful of attempts by Jamie to interfere and treat Shane as a subordinate.
In Series 6, Shane and Kelly caught on camera Liam hiding in the wardrobe of their bedroom, making a separate recording for Mickey. Before they discovered the real reason, however, Liam pretended he was curious about sex, as he was surrounded by it, even with the noise of Frank and Monica upstairs. Despite this, Kelly and Shane, would become friends Liam, looking out for him as he became primarily responsible for taking care of Stella and Frank in Debbie's absence during Series 7.
After the return of Marty Fisher during Series 8, Kelly became the only person willing to give him a chance. She set out to actively help Marty, the brother of her hated sister-in-law Veronica. However Marty soon admitted that he was in love with her, much to Kelly's surprise. Marty was forced to move into a squat and hide from the police, telling Kelly that he wanted for unpaid child care money. He explained that he had left Spain, where he had been living since leaving the Chatsworth Estate originally, when his wife Sue Garland threw him out and began a new relationship.
As the two became closer, Shane began to notice the time they spent together and how little gifts Marty gave his wife had too much meaning behind them to be innocent. First Shane attacked Marty while a screaming Kelly tried to stop him and he later banned Kelly from ever seeing Marty again. However Kelly continued to see Marty in secret, the two of them simply spending time together and talking. Kelly even arranged for Micky to move into the squat with Marty when he needed somewhere to live and the three of them turned the place into a nice place to live. Micky wasn't fooled by her apparent kindness though and told Kelly that the only reason she wanted Micky there was as an excuse to visit Marty's house.
Shane continued to be suspicious however, when the Maguires were laughing at the security footage of an inept post office robbery Shane realized it was Marty and showed Kelly to gauge her reaction. Kelly was able to pass herself off as disinterested in front of her husband but later became both extremely angry and upset when confronting Marty about his actions. The cracks in her marriage continued to grow, with Kelly becoming almost completely detached from Shane. Shane continued to notice the behavior of both Kelly and Marty though and when he discovered that Marty's wife Sue and his two children had actually been burned to death in a fire set by an unknown person, Shane took Marty's history as a pyromaniac and phoned the police. This action of "grassing", so out of character for Shane, shows just how desperate he was and he happily met up with Marty to tell him what he had done and warn him to run.
Things soon took a turn however when Kelly found herself to be pregnant. Though it was something she and Shane had spent years longing for, Shane was infertile and the only person she had not used protection with was Marty (when he paid her for sex at the Brothel). Kelly soon discovered the true fate of Marty's wife Sue and all thought of her pregnancy was temporarily stripped from her mind, she refused to accept Marty's assurances that he had done nothing to hurt his wife or children and only run because he knew how it would look. Later at The Jockey Marty managed to corner Kelly and attempt to apologize for his lies again, telling her that he was leaving the Estate the next day and where he would be catching his bus. The next day, Kelly quietly packed a case and left the Maguire house to leave her husband and be with Marty. But she was late and missed him, calling his mobile she got no answer before realizing it was in a bin at the bus stop.
Kelly sadly went back to Shane in an attempt to fix her marriage but she found she didn't love her husband like she once had. She sat Shane down and told him everything about the baby, though she was careful never to mention Marty it is likely Shane realized. He attempted to change her mind about leaving him, even offering to raise the child as his own despite what it would do to his reputation but Kelly held firm and after the wedding of Mimi and Billy, a resigned Shane let her go.
In Series 9 it quickly became apparent that Kelly has left Shane completely, though she was on good terms with the Maguires, and moved into Marty's squat to be with him and have his baby. Shane even cornered Marty and assured him that the couple would have no trouble from him as he just wanted Kelly to be happy. Micky continued to live with the couple but his lack of enthusiasm for finding his own place and his use of all the milk began to annoy Kelly so much that she eventually forced him to leave. Micky ended up having the last laugh though as just as he was forced to leave, Carmen Kenaway evicted both Kelly and Marty to in her execution of 'Project New Start'. Once the residents managed to put an end to the Project, Kelly and Marty apparently moved into the Gallagher house where they have lived since.
Kelly continued to work at Lillian's Brothel as her pregnancy progressed, with Lillian even making use of her pregnancy for men with a certain fetish, though she said she planned to quit working before she gave birth. Despite the way all the problems Kelly had encountered with the end of her marriage and her new relationship, problems persisted when Marty was unable to cope with her pregnancy. His fear of being a terrible parent and letting Kelly down led to him leaving her alone to cope. Kelly took to talking to a comatose customer from the Brothel in hospital, the man had always been sweet to her and she though he had no one else in his life to spent time looking after him.
She was shocked when a woman caught her in the man's room and identified herself as his wife. Kelly pretended to be just a stranger who had though the man alone in the world and tried to comfort his wife only to discover the woman had been about to leave her husband because he gave her nothing sexually and she had been having an affair. Kelly was disgusted by this news and angrily told her that her husband had no problem with sex when it came to Kelly before explaining that she was a prostitute. The wife was shocked and angry and violently pushed Kelly, who landed stomach down on the metal frame of the hospital bed, before running away. Kelly had a miscarriage.
In Episode 113, Kelly is asked by Lillian to retrieve four grand she has kept in a locker at a train station which is under police surveillance. But when she and Marty find the locker, they discover that there is much more money in the locker than what Lillian stated. They take the money home to count it and find that Lillian had in fact saved up to fifty grand. Kelly and Marty toy with the idea of keeping the rest of the money for themselves. Kelly returns four grand to Lillian, who in gratitude, allows Kelly to take a thousand for herself, which a guilt-ridden Kelly is reluctant to accept. Kelly is torn between keeping or returning Lillian's savings. But Marty takes the initiative of approaching Mimi Tutton to help him launder the money. Mimi approaches Jamie about Marty's request, and Kassi Blanco volunteers his expertise, and manages to come up with forged backgrounds for Marty and Kelly. Kelly is initially angry with Marty for going behind her back, but Marty protests that this is the only way he can help her escape from this life of theirs. Kelly soon approaches Lillian, claiming that she discovered a few more grand in the locker. But Lillian reveals that she knew all along about the exact amount she kept back over the years. Kelly angrily berates Lillian for being so careless with money, and blames her for putting her in that position. But a disappointed Lillian tells Kelly that they have nothing more to say to each other. Apparently ending their friendship. Lillian walks away, leaving Kelly in tears.
In Episode 114 after signing the forms to buy their new home, Kelly and Marty insurance details are found to be fraudulent, and their mortgage is rejected. As they are deciding what to do next, Jamie appears and tells them to vacate No.4 Windsor Gardens, which until that point, they were residing in. Seeing that they have no other choice, Marty and Kelly take their chances and leave Chatsworth.