Alfie was born on 4 March 1964, his parents were killed in a car crash on Valentine's Day and the family mourn their death each year. Although young, he took responsibility for his younger brother Spencer and his grandmother Nana, widely known as Nana Moon.
Alfie use to visit the water fountain at the National Gallery all the time with his Nana when he was a kid. Nana had a friend, that worked at the Lyons' corner house on the Strand. Nana's friend used to give them some cake and they would come and sit by the fountain and eat it.
Alfie recalls a man who would stand by a water fountain and he’d sell pigeon seeds. You would get a bag of pigeon seeds, stick your arms horizontally, like a scarecrow, and they’d fly all over you, pecking at you. It was great.
When Alfie was about 16, he was sitting down by the water fountain with his grandmother and they were staring at this young couple kissing each other. She said "One day that'll be you, Alfie". Alfie replied "Nah, you're the only girl for me, Nana."
Alfie is ejected from Walford East tube station for fare evasion, and causes havoc in the market by getting a refund from Winston for a video he stole and tricking Martin Fowler into giving him free fruit. After acquainting himself with a few residents, he sneaks into The Queen Victoria public house and helps himself to a drink behind the bar. The landlady, Peggy Mitchell, assumes that Alfie is Chris Wright, the new manager sent by an agency. Alfie takes advantage of the misunderstanding to commit identity fraud against Wright. Alfie packs any stock he could find in a bin bag, ready to leave. Jim Branning catches him, but assumes Alfie is throwing away outdated stock and tricks Alfie into giving him a pint on the house. Winston, Martin, Ricky Butcher and Sam Mitchell realise that Alfie has told them all different background stories but he manages to reconcile the inconsistent stories. Alfie later answers the phone to the real Chris Wright and tells him the position is filled, revealing his intention to stay. Alfie's brother and grandmother arrive unannounced in Albert Square and move into the pub with Alfie, much to his dismay. When Alfie is blackmailed by a former police officer, Dougie Slade, who reveals Alfie's true identity to Peggy, Alfie and his family are forced to flee with the pub's takings. However, Alfie leaves the money on Peggy's doorstep. Peggy manages to track him down and after he confides in her about his parents' death, she gives him another chance. Alfie reluctantly accepts her proposal.
Alfie shares a bond with barmaid Kat Slater and an attraction develops. Eventually Kat reciprocates his feelings and one night when the pub is closed, Kat reveals her feelings to him. They decide to embark on their relationship slowly, but his inability to trust her causes her to rethink the romance and she breaks up with Alfie, within less than a week. Alfie is heartbroken when Kat returns from a trip to New York engaged to local gangster Andy Hunter. Andy, knowing Alfie's feelings for Kat, warns him to stay away from her and the wedding. Before the wedding, Kat visits Alfie's grandmother, Nana Moon in hospital, and thinking she is asleep, admits she still loves Alfie. Nana tells Alfie and he rushes to the wedding to confess his true feelings as the ceremony takes place. Kat jilts Andy and he swears revenge before leaving Walford. Alfie and Kat quickly get engaged and decide to hold the wedding on Christmas Day, less than a month away. However, Alfie is still married to his first wife, Liza. Liza's mother, Marlene tells Alfie that their divorce is finalised, so he starts to prepare the wedding to Kat, until Liza reveals they are not divorced. There are only a few days before the wedding so he tries to quickly finalise the divorce while trying to keep it secret from Kat, though Liza makes it difficult as she wants Alfie to take her back. Alfie is forced to cancel the minister on Christmas Day and he panics, but gets his friend Ray to pretend to be a minister, while planning to tell Kat the truth a few days later. Alfie's brother, Spencer Moon, warns Alfie not to start his marriage with a lie, so Alfie reveals the truth to a furious Kat. Alfie is about to tell the guests that the wedding is cancelled when his solicitor enters with Alfie's decree absolute. Alfie convinces the minister to cancel his Christmas lunch, and Alfie and Kat marry.
After a while, Alfie borrows several thousand pounds from Andy to bail out Kat's father, Charlie Slater, who has been arrested for assault. Andy begins demanding cash every week, which he knows Alfie cannot afford. Andy's plan to wreck the Moons' marriage starts to work and Andy offers Kat the chance to pay off the debt by spending time with him in bed. She reluctantly agrees and they sleep together, with a reluctant Kat oozing with guilt. Though unknown to her, Alfie has paid Andy the money. Andy keeps the money and gives Alfie a video tape of Kat cheating on Alfie with him. They watch the sex tape together and she reveals the whole story behind her infidelity. When Alfie insults Kat, she slaps him, with him doing the same thing. Afterwards, the couple attempt to put the incident behind them but their marriage starts to deteriorate and Alfie is unable to trust Kat. She moves out of Walford for while. During her return, it is seen that Kat has become an alcoholic and isn't bothered by the fact that Alfie wants them to resume their marriage. Kat has sex with Roger, a stranger, while intoxicated and finally sees sense, deciding to return to Alfie, but he discovers she has slept with a man she doesn't know and throws her out, so she leaves Walford again.
Alfie shares a mutual connection with Kat's sister, Little Mo Mitchell, whose marriage to Billy Mitchell has collapsed. Alfie helps Little Mo bring up her baby, Freddie, and they decide to announce that they are an item. However, Kat returns before they have a chance, and she makes it clear that she wants Alfie back. He is torn between the two sisters, eventually choosing Kat. He lets Little Mo down gently, and they share a final goodbye hug, which Billy assumes is them getting together. In the pub, Billy drunkenly announces that Alfie and Little Mo are an item. Kat is furious and decides not to get together with Alfie, so as not to break her sister's heart. However, Alfie and Kat continue to grow closer, due to Kat's relationship with Alfie's grandmother, who is dying. After Kat helps Alfie complete some of Nana's final wishes and overcome her death, they long for each other. Alfie announces that he is leaving to drive across the United States in a Ford Capri, and it seems he has gone for good when he waves goodbye to a heartbroken Kat on Christmas Day 2005. After getting drunk and drowning her sorrows in the pub, Kat is stunned to see Alfie waiting for her outside. Kat and Alfie then get into the car together and drive off.
Kat returns to London, revealing that she and Alfie conned a man called Frankie Finnerty and she is now on the run. His relatives Lee and Jono Finnerty track her down but Alfie scares them off by pretending to be a CID officer, though they take most of Kat's money. Alfie and Kat have a heart to heart and it is revealed that Alfie spent six months in prison for property fraud and they tried to have a baby but he has fertility problems. Kat is not interested and tries to leave, telling him that she is pregnant and he is not the father. Alfie doubles the remainder of Kat's money in a bet and promises to stop scamming and get a proper job. Kat gives him 24 hours. He uses Kat's money and uses it to rent The Queen Vic from Phil Mitchell. Kat is angry and demands he get the money back as they need a regular income. Instead, he sets up an illegal drinking den in the cellar and they move into Kim Fox's caravan on the Square.
Alfie hires Greg Jessop to refurbish The Queen Vic and Alfie's cousin, Michael Moon, gives him money for The Queen Vic lease. He introduces Michael to Kat and Michael says that he is returning to Spain and asks her to go with him. He leaves a letter and some money for Alfie, revealing that he is the baby's father. Alfie tells Kat that he wants the baby but she doesn't believe him and agrees to leave with Michael but changes her mind when she sees that Alfie has bought a cot and some baby toys. Alfie struggles to pay the rent and tries gambling again but loses. However, Phil's cousin, Roxy Mitchell, helps out by paying two months rent for him and he shows Kat the newly refurbished pub. However, on the day of the grand opening, there is a problem so the pub doesn't open until the next day. Kat sees Alfie and Roxy together and fights with Roxy. Alfie takes Roxy's side and ejects Kat but they reconcile and Alfie suggests renewing their wedding vows and Kat agrees. The day does not go quite according to plan as Alfie helps Roxy with her sister Ronnie Mitchell's wedding. However, Kat decides that she does not need a big ceremony so she and Alfie have one in the Square with just him and Kat.
Kat gives birth to a boy named Tommy but is rushed to hospital as she haemorrhages, due to a damaged placenta. Charlie decides to join the New Year's party, rather than stay with Tommy so he is unattended when Ronnie Mitchell finds herself in The Queen Vic with her dead son and she swaps the babies. When Alfie gets home, he finds "Tommy" dead in his cot. Kat and Alfie struggle to cope with their loss but eventually start to deal with it until Michael returns, wanting to see his son. Kat tells Michael to leave but he stays because he has friends locally. Kat kisses Michael but he rejects her, leading her to break down. Eventually Alfie moves out after they have a row and goes away for a weekend with Michael. Kat tells Alfie that a coroner has confirmed that Tommy died of Sudden Infant Death Syndrome. He comforts her and they reconcile. Eventually, Ronnie admits to Kat that she swapped the babies and returns Tommy. Alfie and Kat are reunited with Tommy after talking to a social worker. Ronnie goes to prison for her crime and Kat forgives her. She and Alfie holiday in Spain, leaving Alfie's cousin, Eddie Moon, to look after the pub. When they return, they bring Shenice Quinn with them, daughter of Kat's friend, Martina Quinn. Kat finds out she is pregnant and Alfie asks who the father is, refusing to believe Kat has not cheated. Alfie realises he has gone too far but Kat is not interested in his apologies, even after she miscarries. She tells him she does not want any more children and that their relationship will just be for show from now on, leading her to have a one-night stand with Mark Garland, which she regrets after hearing Alfie's voicemail, saying how much he loves her. Alfie takes Kat, Tommy and Shenice on holiday but when they return, Kat tells Alfie that she cheated. They discuss it and Alfie insists that he would rather Kat cheat on him than not have her in his life. Kat isn't happy and is further upset when Alfie will not allow her to explain that she did not cheat again. They try to mend things over Christmas but Alfie hears Kat say that she does not think he loves her. Alfie pays a friend Gerry to claim he is a marriage counsellor and tell Kat that their marriage can be mended. However, when Alfie deliberately leaves them alone, she says she thinks Alfie does not love her and she wants to end the marriage. Gerry tries to tell Alfie but he thinks that Gerry has helped. When Charlie has a stroke, Alfie and Kat visit but he returns alone, Derek Branning gets Alfie into a VAT scam and Alfie helps Roxy and Billy set Derek up by intercepting his alcohol deliveries. Alfie struggles financially and considers firing Jean and stores Derek's goods at the pub to earn extra cash but when Phil demands Alfie stop, Derek arranges with Alfie and Billy to steal a large amount of alcohol. However, Derek is scammed by Alfie and Billy and he suspects Phil conned him. When Billy is arrested on suspicion of murdering Heather Trott, Derek worries that he may implicate them in the alcohol theft and asks Alfie to frame Phil by hiding goods at his garage. However, Alfie is caught and Phil confronts him, making it clear that Alfie takes orders from him, not Derek. When Derek learns that Alfie has told Phil everything, he furiously threatens Alfie.
In Kat's absence, Alfie and Roxy become close friends and Roxy tells Alfie that she is in love with him. This makes things awkward and she quits her job at the pub. After a while, Alfie manages to convince Roxy to return and offers her a place to stay. Jean is conned out of money that belongs to The Queen Victoria while Alfie is away and when he returns, he borrows money from Roxy to pay the bills, angering Kat. Alfie starts a pub football team and pays more attention to that than to Kat, so she starts an affair. Kat tries to resist but eventually the affair turns to love. When Kat's lover sends her flowers, Alfie becomes suspicious and asks Kat if she is seeing someone else. She denies it initially but eventually admits it, refusing to say who the other man is. Alfie demand Kat end the affair but Alfie struggles to trust Kat, especially when he finds a ring he thought had been pawned. Wanting to catch her out, Alfie says he will be away overnight and follows her to a nearby flat, demanding to know who Kat is seeing but she still refuses to name him. Alfie finds a letter to "Mr. Branning" and confronts the three brothers, attacking Max when he sees that Kat is calling. Kat arrives and tells him that she is seeing Derek. Alfie throws Kat out again and Derek makes matters worse when he plays Alfie a message, asking to meet. Alfie punches Derek and tells him that he is barred before giving Derek his wedding ring to give to Kat. Alfie starts dating Roxy and asks her to move in and they declare their love for each other. Alfie helps Kat when she is questioned over stolen goods, but to prove to Roxy that he loves her, Alfie decides to get a divorce. Alfie and Roxy decide to try for a baby, but when Kat and Alfie's decree nisi comes through, it is apparent that Alfie still loves Kat. He is determined to move on so proposes to Roxy and she accepts.
Alfie discovers Ronnie is being released from prison but thinks that she will not return to Walford. He is angry to discover that she has and demands Roxy choose, him or Ronnie. Roxy chooses Alfie but Kat persuades him to accept Ronnie's presence and let Roxy see her sister. Kat supports Alfie after Michael's death and the two become closer. The night before his wedding, Alfie visits Kat and they kiss passionately. On his wedding day, Alfie tells Ian Beale that he still loves Kat but marries Roxy. Roxy realises that Alfie is still in love with Kat and orders him out of the church. He learns that Kat is going to Ibiza and races to the airport. They reconcile, moments before her flight is due to depart. As revenge for Alfie's treatment of Roxy, Phil sells The Queen Vic, forcing Alfie and Kat out. Kat tells Alfie that she is pregnant and they move in with Kat's grandmother, Mo Harris. Kat has a market stall, selling women's clothes, but Alfie isn't as successful as goes to help Spencer in Australia for a while. He returns a month later and tells Kat that he has just bought a classic Ford Capri. After a night in a posh hotel, they return to Walford and Alfie sets up a burger bar on the Square but this is taken away so he sets up a men's clothes stall instead. This doesn't last thanks to a feud with the market inspector, Aleks Shirovs, so he gets a job at Ian's café. Kat and Alfie are thrilled when their twin sons, Bert and Ernie, are born.
Alfie receives a letter from the council, stating that they are due to be evicted from No. 23 Albert Square. He doesn't tell Kat but Stacey finds it and forces him to tell Kat and Mo. Alfie tells Kat that he has got a bank loan but considers starting a fire for the insurance money. Despite Mick Carter advising him against it, he drops a lit cigarette into a paper-filled wastebasket. When outside, he learns Kat is in the house and rushes back to rescue her but Mo's stash of dodgy hairspray causes an explosion, just as Alfie opens the front door. He rescues Kat regardless, receiving minor burns, but Kat is badly burnt. Alfie and the Moons are supported by the local community and stay with the Masood family. Alfie is praised as a hero, despite being suspected by local firefighter Tosh. However, the fire investigation officer declares the fire an accident but Mick advises him not to tell Kat that he started the fire and when Kat thanks him for saving her life, he takes Mick's advice. He is relieved when the fire investigation officer Neil Wallace informs him that the insurers will probably pay for the damage to be repaired but Stacey finds the picture of Nana Moon and realises Alfie started the fire and demands Alfie tell Kat but he refuses, creating a rift between them. The insurance company also refuse to pay for the damage as Mo's quantity of hairspray is listed as commercial goods, invalidating the policy. He tells Stacey Branning and she suggests ringing the insurance company again but Alfie refuses, adamant that they won’t change their decision and blames Mo. Stacey then suggests Alfie use the proceeds from selling the Capri to sort out their finances but he can't as the money was spent on food and the children. Masood Ahmed returns home and asks Alfie when they will be moving out as the house is too crowded but Alfie loses his temper with Masood and accuses him of kicking them out.
Needing a place of their own, Alfie tries to persuade an estate agent to let him stay in number 43 for a couple of nights but the agent dismisses the idea. So he goes to the council for temporary accommodation and is told that all they can offer is one night in a bed and breakfast. Returning to the Square, Alfie tells Stacey about the mess they’re in and she insists he tell Kat the truth but before he can, she asks him to marry her. He agrees and they marry at the registrar's office with two nurses as witnesses and return to Walford. They squat in a couple of places before Mick invites them to stay at The Queen Vic. After an emotional speech from Kat to the social housing manager, they are offered a council house in Hull but just as they are about to leave, Kat finds a photo of Nana. Wanting to know how it survived the fire, Alfie admits that he started it and tries to apologise, but Kat leaves him, moving in with Stacey and Lily. Later, as Christmas approaches, Alfie tells Kat that he will try to fix things.
Mo tells Kat that Harry left her some money in his will. Alfie finds out, and tries to convince her to use the money to make a fresh start after the divorce but she destroys the cheque, insisting it doesn't change the past nor their impending divorce. Kat has second thoughts about the divorce after Pam Coker gives a speech about love and family and Stacey tells Alfie that their rent is increasing and Kat is struggling financially so Alfie invites Kat to his flat for lunch and they reminisce about their relationship. The next day, Kat lashes out at Alfie for leaving leftovers for the kids, but at Stacey's urging, she agrees to be his date to Ian and Jane's wedding if he makes more effort for making up for the fire.
Mo has Harry's money transferred to her account and tells Alfie. He insists that this is not good for Kat and tells her so she burns the money. Sadly, this makes her very depressed and she tries to commit suicide but Alfie finds her and calls an ambulance. At the hospital, he admits that he is still in love with her. He takes her home and decides to stay temporarily to help her with the kids and her assessment by Social Services. During the social worker's visit, Kat is withdrawn and won't answer questions, insisting she is fine but Alfie tells the social worker that they are working on it and admits feeling guilty for starting the fire. After Kat visits a convent, she makes peace with the past and tells Alfie and Stacey that she will claim the money. Alfie and Stacey discover that Kat's claim won't grant her any money so he takes Kat on a trip to central London, giving them a chance to reminisce before having lunch at a posh restaurant. Kat knows that she won't get any compensation and is disgusted when Alfie tells her he already knew. Soon after, Kat takes the opportunity to tell Alfie that she wants them to reconcile and although initially resisting, he changes his mind once back in Walford. On the spur of the moment, they buy a scratchcard and realise they have won £1,000,000. Alfie and Kat decide to use the money to move somewhere new and run a bar. Alfie suggests going to Australia but he and Kat decide to return to Spain so she can be closer to Zoe. But after tests, a doctor tells Alfie he may have a brain tumour. Kat buys plane tickets for the next day and Alfie chooses not to tell Kat about the tumour and ignore warnings that the tumour will grow. Sonia Fowler also advises him not to fly as this could cause problems so they drive to Spain.
On Christmas Day 2015, Kat returns to Walford to spend Christmas with Stacey. Alfie follows with the boys. While at Mick's stag party, Alfie tells Ian and Phil that he may have a brain tumour. Ian and Phil go with him to a hospital appointment, where he learns that the tumour has stopped growing but he may need an operation if he begins showing symptoms. Alfie tells Kat about his tumour and in turn, Kat tells Alfie that she has a son living in Ireland. After Charlie dies from a heart attack, Kat and Alfie decide to search for her son. After saying their goodbyes, Kat and Alfie depart.
Having recovered from his operation, Alfie and Kat return to Spain to run a bar. Mo returns in March 2018 and reveals that Kat and Alfie had an argument and that he fled with the children shortly afterwards and no one knows where he is. On her return to Walford shortly afterwards, Kat reveals that Alfie is in Spain with their children, running a different bar with a Russian partner, Dimitri, after their old bar lost a fortune. She insists that the two are taking a break from their marriage. Two months later, Hayley Slater visits Alfie, who is staying in London, and it is revealed that Alfie threw Kat out after Tommy accidentally caused severe burns to Ernie while she was in bed with Dimitri. Hayley reveals that she is pregnant and that Alfie is the father following a drunken one-night stand in Spain. Alfie tries to persuade Hayley to terminate the pregnancy and returns to Spain, but Hayley decides to keep the baby.
Kat gets a video call from Alfie and he asks her to collect something for him. Believing him to still be in Spain, she follows his instructions and goes to a chapel where she is surprised to see Alfie in person. Alfie is running a funeral business and has many clients lined up, but Kat is unimpressed and only sees it as a scam. She is angry that he has not brought their children with him, but apologies for cheating on him with Dimitri. Kat tells him to stop his lies and jokes and she leaves. The following week Kat speaks to Alfie, who is back in Spain, by video call and she is angry when he says he lied to her and actually did bring the children with him to London. Two weeks later, during Hayley's birthday party, Kat answers the door and is shocked to see Alfie standing on the doorstep. Though he reunites with Kat, he is stunned to realise that Hayley did not terminate her pregnancy, and insists they keep the truth hidden from Kat. Hayley develops feelings for him when she sees him bond with their daughter, named Cherry by Alfie after his deceased mother. Jean, who is the only one who has found out about Alfie being Cherry's father, insists that Alfie tell Kat or she will.
Stacey sees Hayley and Alfie kissing and is horrified to uncover Cherry's paternity and issues an ultimatum: one of them leaves, or Kat learns the truth. Hayley decides to go, but her parting gift to Alfie – a lock of Cherry's hair – is discovered by Kat and she works out the truth. After a furious showdown, Alfie turns nasty with Kat, who accuses him of taking advantage of Hayley's vulnerability. Hayley defends Kat and pushes Alfie, causing him to fall down the stairs and knock himself unconscious. Believing that he is dead, Hayley, Kat and Stacey discuss what to do to protect Hayley from going to prison. Kat privately says a tender goodbye to Alfie, kissing him and telling him she loves him. As the police arrive, they discover that Alfie survived and has left, taking Cherry with him. The next day, Alfie meets Phil, who gives him fake passports but warns Alfie to think carefully about his plans. Alfie eventually contacts Kat and Hayley via video chat and says he will bring Cherry back soon. On New Year's Day, Alfie and Kat meet and Kat tries to talk him into returning Cherry but Alfie admits he cannot bring himself to do it, fearing he would only be granted limited visitation time, and suggests he and Kat adopt Cherry and leave together. Kat tells Alfie she accepts and brings Alfie to the house, claiming it is empty but when Alfie arrives, he is confronted by Stacey, Mo and Jean. Angry and upset, he shows them Ernie's scars caused by Kat's irresponsibility. When Kat takes the children for ice cream, she gives Alfie the option to take them with him on the condition that he brings Cherry back to Hayley. Alfie eventually relents to return Cherry and leave their children with Kat, admitting that he loves her and only wanted her to be happy. The next day, after emotionally attempting to say goodbye to Cherry, Alfie changes his mind and attempts to drive out of Walford with her but finds himself stuck in traffic. This forces him to reevaluate his decision and he turns back and returns Cherry to Hayley. An overjoyed but protective Hayley tells a dejected Alfie that she cannot let him be a part of Cherry's life. After learning of this from Ian, a sympathetic Kat allows him to spend time with their children.
Several days later, Alfie does some DIY work at the Slater house, while Kat resists all his attempts to charm her but eventually relents to an early birthday lunch at The Queen Vic with him, Mo, Stacey, her husband Martin Fowler, Jean Slater and Cherry, whom Hayley allows him to bring along for the day. After finding that his credit card has been declined and making a toast to Kat, Alfie receives a phone call from the bank, causing him to rush over to the Beale house where he is staying where he finds overdue bills from running his funeral business. The next day, after Alfie unsuccessfully tries to help Hayley with feeding Cherry her breast milk, the father of a deceased client accuses Alfie of stealing his son's money after a mix-up with the funeral plans, and Ian threatens to kick Alfie out for stealing his food. Under stress, Alfie confesses his troubles to a horrified Kat, including the fact that some of the money was paid for her new fireplace. In order to reimburse the client's family and pay the bills, Alfie decides to look for investors for the business and Ian offers to buy a 50% stake in the business for a loan with 20% interest, which he accepts. Later, after explaining this to a concerned Kat, who reprimands him for his schemes, Alfie and the rest of the Slaters are stunned to find Hayley unconscious from drinking after locking herself in the bathroom with Cherry. Knowing she's struggling being a mother, Alfie suggests to Kat that they adopt Cherry, but Kat isn't sure. Soon after, customers of Alfie's funeral business start contacting him and one coming to see him in person, accusing him of swindling them of money. Needing to pay them back, he persuades Phil to lend him 30,000 pounds and offering his expensive car as collateral. Alfie then does a runner and Phil is angry when he takes the money and the car with him. Phil threatens Kat, saying she will pay back the money to him if Alfie doesn't. When she gets a text from Alfie telling her to look in the wardrobe, she's stunned when the money falls out of it, having left it behind for her. Although the text says he'll be returning soon, he doesn't come back. Kat uses the money to pay for Jean's cancer treatment, leaving her in further debt to Phil. Phil later demands Kat find Alfie but she assures him she doesn't know where he is.