Shane Maguire is a member of the Maguire family, Chatsworth Estate's gangster family, known for his short and unpredictable temper and originally limited intelligence. He fell in love with prostitute Kelly Ball, who despite the early interference of his father, Paddy, he later married.
Originally Shane was portrayed as extremely volatile with very low intelligence. When his sister Mandy was given a larger role in the family business of dealing drugs, Shane decided to get revenge and hopefully get himself promoted by anonymously reporting her to the police and getting her arrested. Though he thought himself lucky when Carl Gallagher got the blame, Lip was so intent on both getting his brother out of trouble and getting Mandy out of jail that he figured out that Shane was to blame. Lip told Shane that if he got the Maguires off Carl's back, he wouldn't tell his family what he had done.
Shane slowly began to change over the course of the show, going from being a minor, almost two dimensional character to a full fledged main player on the Chatsworth Estate. He eventually met Kelly-Marie Ball, a prostitute at Lillian's Brothel and fell for her quickly. He visited her for sex regularly and the two became closer, and though Kelly didn't seem interested at first she eventually took an interest in Shane. Their relationship almost ended however, when Shane's disapproving father paid Kelly a large sum of money to disappear. Kelly took the money and left the estate for a while, but she eventually returned, gave the money back to Paddy and revealed to Shane what had happened. Shane went berserk and attacked his father, but Paddy's experience was too much for him and while both friends and family looked on in horror and disgust, Paddy brutally beat his son in The Jockey.
Eventually the Maguires hesitantly accepted Kelly into the family after she found Katie, who had gone missing after Carl Gallagher left her with a girl he knew from the park. Kelly continued her work at the Brothel and the couple eventually married. Their relationship took another hit however when Kelly became pregnant, while Shane and the family were thrilled Kelly wasn't convinced it was a good idea and toyed with the idea of an abortion. Kelly was shocked and even hurt to discover that she wasn't pregnant at all, it had been a phantom pregnancy and she was comforted by Shane and Mimi.
From Series 6, Shane and Kelly tried to find a means of developing an income quite apart from the Maguire clan. In Episode 7 of Series 6, they attempted to make home-made porn movies, but Micky hired Liam Gallagher to secretly film them. They later found out that Micky was selling copies of the alternate recording, and shook him down for the money he made. The following episode, Shane and Kelly developed a tactic to blackmail businessmen who were having extra-marital sex. But one occasion involved a desperate victim of their scam smashing Shane's head into a dresser, putting him in a coma. Shane woke up to find himself partially paralysed, but with the help of Kelly and Meena Karib, Shane made a gradual recovery.
In Series 7, Shane's indifference to his mother Mimi replacing Kelly as the godmother of Jamie and Karen's newborn son, put him at odds with his girlfriend. When he tried to make amends with Kelly after telling Mimi to "back-off", Liam told Kelly that the Bible apparently condoned prostitution, rendering Mimi's excuses on religious grounds invalid.
At the beginning of Series 8, Shane and Kelly became more and more angry with how they were forced to hand over a large part of any money they made together, as part of the Maguire family business revenue. When Mimi collapses at a party and is put in hospital, she hands over the reigns of the family business to Shane while she recovers. Jamie disagrees with his mother's decision but she reasons that he has to work through his problems with Karen and his son while Micky is busy looking after Cilla. Kelly is especially pleased by the news that she is now the wife of a real crime boss, while his brothers have misgivings about his leadership skills. Jamie meanwhile, decides that if his mother won't agree with him, he'll have to make Shane want out. Shane makes some mistakes of his own while Jamie sets things in motion behind his back, resulting in Shane getting ripped off and losing a huge sum of money. To save the business he borrows money from a local loan shark, Chemical Mitch who has a particularly bad reputation.
When Mitch begins hiking up the interest and demanding quicker payments, Jamie tells Shane that something has to be done and takes him to kill Mitch. Shane didn't want to do it but eventually he pulled the trigger and committed his first murder. As Jamie had intended, Shane steps down and Jamie takes over the business. As time passes the two brothers relationship is all but destroyed and eventually Shane and Kelly decide to officially split from the family business and work alone. The breakdown of the family dynamic ends when Shane steals the wheelchair of a local celebrity and the whole estate wants his blood. Jamie pulls a gun on Shane and demands he leave the estate and never return but Shane managed to get the gun away from his brother, shoots him in the leg and explains how he would never forgive himself or Jamie for making him kill Chemical Mitch. Jamie explains that he hated himself for murdering so many people too, but he did it to keep the family safe and so his brothers didn't have to. The boys relationship reconciled, Shane and Kelly became more involved with the family business once more.
Kelly and Marty
Late in Series 8 Marty Fisher returned to the Chatsworth Estate. Marty sought out Kelly due to her being his sister-in-law and explained how he had lost his wife Sue Garland to another man and wasn't able to pay child support for their two children so was forced to lay low due to the warrants. Kelly and Marty began to spend a lot of time together, Kelly finding herself happy again after feeling her marriage had slowly become stale. Shane soon realised that Marty was more than just a friend or a customer however and proceeded to beat Marty and warn him to keep away from Kelly. Kelly was horrified and the two argued over the fact Shane was telling her who she could and couldn't see. Marty soon sought Kelly out again and though she explained it would be best if they didn't see each other any more, he blurted out that he loved her. They continued to see each other after this however, Kelly suggesting Micky move into Marty's in what Micky later suggested was an excuse for her to see Marty. Shane began to get visibly suspicious and when Marty was caught on CCTV holding up a post office Shane made a point of talking to Kelly about it, she pretended not to be interested but later rushed to Marty to chastise him.
Kelly later discovered that she was pregnant and with her use of condoms at work and Shane's infertility the only possible father was Marty, who she had unprotected sex with out of a mixture of business and pleasure. Panicking, she eventually admitted everything to Shane, seemingly wanting him to end their marriage but he reacted in the opposite way. Shane suggested they raise the child as their own, ignoring any jibes from locals who knew Shane was incapable of fathering the child himself, all out of fear of losing his wife. But this denied Kelly of the anger she wanted and felt she deserved from him, she told him that if he ignored her cheating and raised someone else's child he wouldn't be the man she thought he was.
After a short time Shane's desperation to keep his wife turned to sad acceptance and Kelly left him for Marty. By the beginning of Series 9 a visibly pregnant Kelly was living with Marty and though there appeared to be some awkwardness between her and the Maguire family, they have been uncharacteristically accepting. Shane also visited Marty briefly at home to tell him that Shane would give the couple no trouble.