Aidan Croker is the child of Sinnead and nephew of Patty Croker. His father was a Gypsy that left his mother to marry someone else while Aidan was still a baby, his mother has a break down as a result and became a drug addict and later a prostitute to fund her habbit. He moved onto the Chatsworth Estate to live with his aunt while his mother was in prison for assaulting a customer. Though only young Aidan has proven himself to be a seasoned trouble maker and clever criminal, using his god mother Libby's credit card to pay for porn, working with Micky Maguire to make a fake child porn website and then setting up his own with friend's from school and even deciding to burn out his god mother library on wheels for the insurance money when the family was having money troubles.
Aidan has also become firm friends with Letitia Powell, another recent edition to the estate whom Aidan has "coached" in various ways, including using the affair she though her father was having as black mail for money and presents.
Though Aidan was told his mother Sinnead was going to court for shoplifting, a misunderstanding, she was more likely there as a result of her drug addiction or prostitution. She was jailed for 18 months, leaving Aidan to live with Patty and Libby in the Gallagher house.
Aidan got mixed up with the Maguires when his hope of a kiss from Letitia lead his astray. Letitia told him that various boys had given her expensive presents for as little as her bending over in front of them and as Aidan wanted a kiss, he would have to give her something valuable. When they found a hidden spare key to the Maguire house Letitia decided she wanted a picture on Aidan's phone of Paddy Maguire's corpse. Unknown to the children, Paddy had faked his death and the coffin in the house that everyone thought contained his body actually contained smuggled Irish guns at first and later that of a man killed by Jamie Maguire and the murder weapon. Aidan snuck into the house and though he didn't get a picture of a corpse, he did steal the gun. Letitia realized how stupid such a move was and told him to put it down, but his finger caught on the trigger firing 2 shots, one into the Maguire's window.
Letitia panicked and took the gun away from him, later hiding it under the cushions of her sofa only for it to be confused with a water pistol from her mother's new job as a clown. Aidan later snuck back into the Maguire house and took a picture of the man inside the coffin, assuming it was Paddy Maguire. Aidan got his kiss from Letitia after showing her the photo on his phone, but it was still in his hand clearly showing when the Maguires walked past. The lost gun was eventually found but not before Aidan was held face to face with a corpse and broke down out of fear when Jamie held what he thought to be the gun to his head and then fired it revealing it as a water pistol. Later in the series, Aidan developed a relationship with a visiting Christian girl named Grace. Grace came to the estate on a Double Decker bus that was the base of a group of Christian missionaries lead by Jesus O'Toole. Aidan's aunt Patty was among them, after leaving the estate for a while when the residents discovered she had been lying for 30 years and could actually walk. Grace was in charge of leading prayer meetings and tempting younger people to them with the promise of time on various game consoles. Aidan was drawn in both by these toys and as a spy for the Maguires. He and Grace got on well and eventually they were caught when on the bottom floor of the bus Grace gave Aidan oral sex under a table. When the Christians were eventually run out of the estate, Aidan gave Grace a mobile phone, hinting that it was stolen and she gave him a console game. Aidan also told her that if she was ever near again, to call him.
Aidan became excited toward the end of the series when his mother's prison release date arrived. He left the Gallagher house and waited outside the prison for hours before discovering his mother had been released 2 months earlier. He agonized over the fact she hadn't contacted him but decided she must be trying to get her life on track first. Aidan was also put on an electronic tag and curfew when he threw a brick through someone's window, this along with his mother's lack of contact lead to him going "off the rails" for a while. In a rare show of maturity, Carl was the one to step in and help Aidan through a difficult time. Aidan eventually tracked down his mother and went to visit her, she lit him a cigarette and explained that she had been clean for a year and had just wanted to prepare her flat before taking him back but she soon ran out of the house. She later returned with Patty and explained that she couldn't take Aidan back as he would lead her back to drugs, blaming him for her addiction and prostituion. An inconsolable Aidan and disgusted Patty soon left but not before Aidan told her he loved her and that if him not being there meant she could be a better person he would hold her to it.