Andrew is first seen when Heather Trott and her friend Shirley Carter go to a 1980s festival in Southend-on-Sea, though Heather has not told Shirley it is for couples. Shirley walks out but when she returns, it is too late for them to go in but Andrew, who is working on the door, lets them in anyway. Heather tells Andrew that she and Shirley are lesbians as the event is for couples, but he thinks Heather is lying, and she admits it. When Andrew talks to Shirley, she says Heather is not interested and Heather thinks Andrew is more interested in Shirley. Eventually, Shirley tells Heather that Andrew likes her, but did not tell her in case it was purely for a bet. This upsets Heather, who tells Andrew the bet is off. Heather soon realises she was wrong and meets Andrew in the restaurant of the hotel where she is staying. Heather's friend [[Dot Branning] arrives wit]h her half sister Rose Cotton and it is revealed that Andrew is Rose's son and they do not get on. Andrew and Rose trade insults at the table and he and Heather decide to leave. Heather tells Andrew he should not speak to his mother that way and decides to leave. Andrew finds out Rose has decided to live with Dot and will be left on his own. He drives them to Walford and finds Heather, and she says she will find him next time she is in Southend. He tells her his name as Andrew Cotton, revealing to Dot that his father is her first husband Charlie Cotton, and that he had a third bigamous marriage. Andrew then returns to Southend.
Andrew returns to Walford in December and promises to stay for Christmas, much to Rose and Dot's delight. He meets Heather again, and vows to her that he will make up for his past mistakes with her. Heather initially rejects him, but then they share a kiss. He later asks to spend Christmas with her, and she agrees. Andrew starts working as a doorman at the R&R nightclub. Heather is upset when he chooses to work instead of spending the night with her. Andrew leaves Heather several messages, explaining he was scared and he will wait in the café until she arrives. However, he is asked to leave because he is taking up a seat and he refuses. In his anger, he pushes a table over, which Heather witnesses. She forgives him, and the couple soon admit their love for each other. They attend a dance class with Kim Fox and Heather is impressed with Andrew's dance moves. He also picks up a poster about gastric band surgery, which Rose finds and confronts Heather about. He tells Heather he is fixing Dot's tap but Heather thinks he is having the surgery, but he reveals he was looking for an engagement ring. He proposes and Heather accepts and they have sex for the first time. Andrew soon notices that Heather spends more time with Shirley than with him, and gets angry with Heather. Heather and Andrew settle their differences and spend more time together.
At Heather's hen night, Andrew's temper emerges again when he almost hits Shirley and it is revealed that Andrew went to prison for assaulting Rose's husband. Heather stays with Andrew as he explains that Rose's husband regularly abused her. Sick of the interference in their wedding, Andrew suggests to Heather that they elope. Heather is unsure, so he gives her two train tickets and tells her to meet him at The Queen Victoria public house by 6 pm if she wants to elope with him. Heather does not arrive, so Andrew gets drunk, leaves the pub and considers leaving Walford. He is persuaded to stay by a homeless man, Gerry, and returns to Heather's flat, only to find that Heather has been murdered. Andrew is arrested by the police, as he doesn't have an alibi for where he was when Heather died and they suspect him as he cannot prove that a tramp stole Heather's money from him. However, he is eventually released without charge. Shirley confronts Andrew and publicly accuses him of murdering Heather. However, when it is suggested that Andrew should leave Walford, he declares that he plans to stay. Dot doubts Andrew's innocence but when Andrew opens up to Dot about his feelings for Heather, Dot changes her mind. This leads to Shirley banning Andrew and Dot from Heather's funeral. However, Shirley later finds the train tickets that Andrew gave Heather the night she died and realises he is innocent. She later admits that she wanted him to be the killer as she was jealous and the pair agree to unite to find Heather's real killer. Dot and Rose eventually leave Walford, leaving Andrew with no family there. Heather's killer is eventually revealed to be Ben Mitchell after he confesses to the police. When Jay Brown is released on bail charged with perverting the course of justice for protecting Ben, Andrew accuses Shirley of protecting them as they were living with her. When he sees Jay, he attacks him in The Queen Victoria by pushing him onto a table. The next day, Andrew realises that he will never be able to move on as long as he stays in Walford because of the memories and decides to leave.