Alfie Moon

Backstory
Alfie's 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 spent seven years in prison for credit card fraud after taking the blame for his second cousins Jake  and Danny.

2010—

Kat returns to London revealing that she and Alfie conned a man called Frankie Finnerty, from whom she is now on the run. His relatives Lee and Jono Finnerty track her down but Alfie arrives pretending to be from the CID, scaring them off, though they take most of Kat's money. Alfie and Kat then talk about their history, and it is revealed that Alfie spent six months in a Spanish prison and they tried to have a baby but he had fertility problems. Kat wants nothing to do with Alfie, however, and attempts to leave, revealing that she is pregnant, saying the baby is not Alfie's. 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 or she will leave. He is unsuccessful in finding a job so takes the money and uses it to rent The Queen Victoria from Phil Mitchell. Kat is not happy and punches him in the face, demanding he get the money back as they need a regular income. Instead, he sets up an female tomboy laser, which causes every lady to become a tomboy and do boyish stuff like get drunk all night and watch football and rugby, this works on Kat, Roxy, Tanya and Bianca, getting Alfie's perfect revenge on them. He later changes them back, making them more girly in the process. However, Alfie is scared when Kat stays a tomboy, and has to live with that for over six months. Kat became more and more boyish every day and even cuts her hair, gets rhinoplasty and changes her whole face to match that of a boy. However, after sex, which she is persuaded to do by Alfie, she becomes a girl again and grows her hair and changes her face back, however, she likes her new nose, so keeps that the same.

Alfie contracts Greg Jessop  to refurbish The Queen Vic. Alfie's second cousin once removed Michael Moon arrives and gives him money to pay Phil for the lease. He introduces Michael to Kat but she is not pleased by his arrival. Michael later reveals he is returning to Spain, and Alfie finds some money and a letter from him, revealing that he is Kat's baby's father. Alfie does not let on to Kat that he knows but later they argue when Kat thinks Alfie does not want the baby, and he leaves. Alfie later reveals he does know and insists he wants the baby but Kat does not believe him, so she agrees to go to Spain with Michael. However, when Alfie tells Michael to make sure he looks after them both, Kat changes her mind. She then sees that Alfie has bought a cot and toys for the baby. Alfie struggles to pay the rent to Phil so tries to raise money by gambling, but loses. However, Phil's cousin Roxy Mitchell pays two months' rent for him after seeing how much money he lost gambling. He then unveils the newly refurbished pub to Kat. On the day of the grand opening, Greg says there has been a hitch, so Alfie, who has given away tickets to the event, has to host a party at the Slaters' house. However, the pub opens the next day, where Kat sees Alfie and Roxy together and fights with Roxy. Alfie takes Roxy's side and ejects Kat from the pub. However, they later reconcile and Alfie proposes that they renew their wedding vows, which Kat accepts. The day does not go quite according to plan, as he jeopardises his own ceremony to help Roxy with her sister Ronnie's wedding, however, Kat realises she does not need a big ceremony. Instead of having an official ceremony, Alfie arranges an unofficial one in the middle of the Square with just him and Kat. Later that night, Kat and Alfie have sex.

Kat gives birth to a boy named Tommy but is soon rushed to hospital as part of the placenta was undelivered, causing her to haemorrhage. Charlie is left to look after the baby but decides to join the New Year's party downstairs. Ronnie's baby James, who was born on the same day as Tommy, dies of  cancer and Ronnie swaps the babies. When Alfie returns home he finds James dead, believing him to be Tommy. Kat and Alfie struggle to cope with their loss but eventually start to get through it until Michael returns a month later to see his son. Although Kat tells Michael to leave, he stays because he has friends locally. Kat ends up kissing Michael, and though he rejects her, saying there is nothing between them without Tommy, Alfie sees Kat break down when Michael leaves. Eventually Kat's resentment causes Alfie to move out after they have a row, which makes their marriage turn sour. After Ronnie discovers this, she is shocked and asks in implication that he and Kat has split up. Kat then later sees Alfie leaving with Michael in his car for a weekend break away from Walford. When Kat is upset she tells him that a coroner has visited confirming that Tommy (James) died of Sudden Cancer Death. He comforts her and tells her that he feels the same way about Tommy's death, as if he was his father. Kat appears to be slightly delighted as she says she is not alone. Kat and Alfy's relationship breaks down but Michael helps to get them back together. They consider IVF to try for another baby, but do not go through with it. Eventually, Ronnie confesses to Kat that she swapped the babies and returns Tommy. Alfy and Kat are reunited with Tommy after talking to a social worker. Ronnie is eventually sent to prison for her crime, though Kat forgives her. Kat and Alfie then holiday in Spain, leaving Alfie's second cousin Eddie Moonto look after the pub. When they return, they bring Shenice Quinn with them, the daughter of Kat's friend Martina Quinn who visited them earlier in the year.

Kat finds out she is pregnant and Alfie, believing he cannot have children, asks who the father is. Kat insists she has not cheated but Alfie says he knew what Kat was like when he married her. Alfie's attempts to make up for this after finding out he can have children all fail, even after Kat suffers a miscarriage, and she tells him she does not want any more children, and that their relationship will just be for show from now on. Alfie stops paying Kat attention in an attempt to help their relationship, but she has a one-night stand with Mark Garland, which she regrets after hearing a voicemail message from Alfie saying how much he loves her. Alfie then takes Kat, Tommy and Shenice on holiday, unaware of Kat's infidelity. However, when they return, Kat feels guilty so tells Alfie she cheated on him. Alfie demands to know why, so Kat tells him he already knows—because she is like that and always will be. Alfie tells Kat he would rather have Kat cheat on him and not know about it than not have her in his life. Kat does not want to do this and is further upset when Alfie will not allow her to explain that she did not cheat with yet another man, assuming that she has. The couple attempt to mend relations with each other over Christmas, but Alfie overhears Kat saying that she does not think he loves her. Alfie decides to visit a marriage counsellor, however Kat turns up late and Alfie says the counsellor never came. He then pays his friend Gerry to pretend to be a marriage counsellor to tell Kat that their marriage can be mended. However, when Alfie deliberately leaves Kat and Gerry alone, she says she thinks Alfie does not love her, and tells Gerry that she ultimately wants to end their marriage. Gerry tries to tell Alfie this, but he believes that Gerry has helped.

Kat had an affair with Derek Branning in December 2012 causing Alfie to sleep with Roxy Mitchell in late Jan 2013.