Declan was originally introduced in April 2010 as a business partner of Natasha Wylde, but then became the owner of Home Farm when Natasha was imprisoned in November for the murder of her husband Mark. Declan went out with a bang when he fled the village in October 2014 after trying to murder his third wife Charity Macey and accidentally killing his nephew Robbie Lawson.
2010-2011: Arrival in Emmerdale
While he is at a hotel in April 2010, Declan meets Charity Tate, who flirts with him and then steals his car. Declan later spots Charity in The Woolpack and blackmails her into going on a date with him. Declan kisses Charity, knowing that it will make her boyfriend, Cain Dingle, jealous. Declan buys a share in Home Farm from Natasha Wylde, unaware it is her son Nathan's share, which he demands back. Declan even asks former Home Farm boss Alan Turner for advice on how to run Home Farm. Declan and Natasha begin a secret relationship and Declan buys a house in the village. When the body of Natasha's husband Mark is found, Natasha's daughter Maisie tells Declan she thinks Nathan killed their father. Declan confronts Natasha, believing she is covering for Nathan, and offers to help. Natasha insists that Nathan is not responsible and Declan ends their relationship. Declan employs Nicola King as his estate manager. He offers to help Faye Lamb contest Mark's will in order to take over the estate and supports her when her son Ryan is accused of Mark's murder.
In November 2010, Declan gets a call from his ex-wife in Singapore telling him that his daughter has been injured in a road accident and he flies out to visit her. On his return, Declan comforts Faye when Ryan is found guilty of murdering Mark. Natasha confesses to Mark's murder and Declan makes Nathan an offer for her share of Home Farm. Nathan refuses and later sells to Ella Hart, unaware that she is Declan's wife. Much to Declan's annoyance, Ella makes herself at home. Declan and Ella's daughter Mia later find Declan with Alicia Gallagher. Declan's father Dermot Macey arrives for Christmas at Ella's invitation. Declan pays Dermot not to stay, but he later finds his father at Home Farm with Ella and Mia. When Declan discovers Ella is having an affair with Mia's boyfriend, Adam Barton, he furiously throws her out, but promises not to tell Mia.
2011-2013: Relationship and marriage to Katie Sugden
Declan starts dating Katie Sugden and Ella tries to warn her off. Declan accidentally tells Mia about Adam and Ella's affair, breaking Mia's heart who refuses to forgive her mother. In August 2011, before Ella leaves, she tells Declan that his friend Jai Sharma is actually Mia's father after she cheated on him many years ago. Declan confronts Jai and tells him to stay away from Mia. Declan later asks Dermot to take Mia back to Ireland as it was starting to be hard to be around her with this new revelation.
In November 2011, Katie encourages Declan to get in touch with Mia and he invites her to visit. However, on the day she is due to arrive, Declan is told that Mia has died in a car accident. He breaks down and begins ignoring Katie. Katie believes they should end their relationship, but Declan proposes. She turns him down but agrees to move in with him. Declan and Katie come across John and Moira Barton after a serious car crash. Declan rescues Moira, but the car falls from the cliff and crashes to the ground with John still inside. John is rescued and taken to hospital but dies that evening. Declan pays his respects to Moira and then asks if he can use their field for a music festival. Adam overhears the conversation and tells him to leave. Declan's half-sister, Megan arrives in the village in February 2012 and helps Declan with the music festival. Megan and Katie clash numerous times. Megan admits that she gave a child up for adoption and Declan finds her son, Robbie. Katie shows Declan CCTV footage of Robbie trying to kiss her. Megan suspects Katie made it up and blackmails Declan into letting Robbie stay, causing Katie to move out. On 7th September 2012, Declan apologises and he proposes again, which Katie accepts.
Declan tells Katie that he plans to keep the proceeds from the festival. On 17th October, Declan and Katie marry. In late November 2012, shortly after the couple argue, and Katie falls into a disused mine. She is later found by Sam Dingle on the moors in a critical condition. Katie recovers, but a shattered pelvis temporarily confines her to a wheelchair and further damage means that her chances of her having any more children are minimal. When Katie recalls her argument with Declan, she decides to leave. In 2013, Declan has a one-night stand with Charity, but when Katie comes back, she and Declan reconcile. However, Chas Dingle learns about his one-night stand with Charity and tells Katie. She then publicly humiliates Declan and has a one-night stand with Adam, making sure Declan catches them. Declan and Katie clash several times, and they begin divorce proceedings.
Throughout late 2013, Declan began physically abusing Megan. Katie witnesses one of Declan's attacks and sticks up for Megan, despite Megan saying that it was just a misunderstanding. During excavation for the music festival, bones are discovered on the land, but Declan pays the crew to keep going with the work. The police tell Declan that the bones are in fact the remains of Alex Moss. In August, When a worker tells the police that Declan paid him to keep his mouth shut and continue working, Declan is arrested for perverting the course of justice.
2013-2014: Marriage to and attempted murder of Charity Dingle
One night leading up to Christmas 2013, when Charity takes Declan home, he douses the living room with petrol. Charity tries to stop him, but he sets the room on fire in a bid to end his life. However, he changes his mind and flees the scene with Charity. They later learn Megan was in the house, but that she was rescued by the fire brigade. Looking for a way out of the damage Declan has caused, he and Charity decide to create a scam so they can claim the insurance money, leading to framing Sam and his girlfriend Rachel Breckle for the crime. Charity then forces Rachel to take her son and leave the village. Declan and Charity soon begin a relationship, but in April 2014 Charity is horrified when she becomes pregnant and plans to have a termination. However, Megan finds the positive pregnancy test and reveals this to Declan who is delighted, and proposes. Although she initially refuses and walks out, she later changes her mind and accepts.
In May 2014, Charity and Declan's wedding take place, but it's interrupted when Megan, who hates Charity, sets off the fire alarm and hides the rings in an attempt to halt things going ahead. After Charity confronts her, they fight, which Declan breaks up, but they still marry, Megan forced to lend Charity one of her rings. During a second argument with Megan, Charity falls when Megan grabs her and later lies to Declan that she has had a miscarriage. He is devastated the hospital staff confirm she has lost the baby. A guilt-ridden Megan admits that she is to blame, leading to Declan forcing her out of the house. Incensed, Megan vows revenge on Charity, and takes the chance when Robbie finds an address to the abortion clinic on the satnav. They try to convince Declan that Charity had an abortion, but he refuses to believe her, while Charity manages to come up with an excuse.
In September 2014, when Charity's son, Noah steals a bottle of wine, he collapses and is taken to hospital, where it is revealed that the drink was laced with pesticide. A suspicious Declan begins to doubt Charity, but stands by her when she accuses Megan of trying to poison her, because of their long-running feud. Worried for her health, Declan persuades Charity to go away to a cottage for a break. Whilst his behaviour begins to unnerve Charity, she remains otherwise oblivious. He puts the pesticide container into the boot of his car when Charity is inside, revealing that he was involved in the poisoning.
At the cottage, he begins acting suspiciously and takes Charity's phone and smashes it in the woods, and calls Megan to tell her that he believes her about Charity's abortion. When Megan begs him to come home, he darkly tells her everything is going to be alright, but his unhinged temperament insinuates that he is going to kill Charity. Charity, who has followed him, overhears the conversation and returns to the cottage, but is seen by him. She is horrified when the car does not start, and begins to panic. Declan comes back and locks the door, but coerces her into coming onto a boat trip. He goes to the kitchen to find wine, but when Charity approaches him with an axe from behind, he turns around and manages to knock her unconscious with a meat mallet. He places her body in the boot of his car, intending to bury her body in the woods. After calling Debbie Dingle to tell her Charity has gone missing, he opens the boot, but Charity has come around, kicks him and escapes. He follows her through the woods and eventually catches her, where she begs for her life, telling him they can get a divorce. Declan ignores her, before revealing he was responsible for trying to poison the wine, although he adds he never meant for Noah to get hurt. He attempts to kill her again, but Charity knocks him into a shallow grave he dug for her and flees.
Declan has another plan to kill Charity. She pulls her and himself onto a lifeboat at Kilbeck Water and leaves it stranded halfway out the lake. Charity tries defending herself by using a flare gun on Declan, but he manages to grab it from her. Megan and Robbie arrive at the dock. Declan jumps in the water in an attempt to save Charity. Declan pulls out the flare gun to shoot Robbie, but Charity stands in his way. Declan aims the gun at Robbie and shoots him, making him flip over the boat and float in the water. Declan jumps off the boat and into the water to find dead Robbie, but there is no sign off him. The police detectives, Debbie and Pete Barton arrive at the dock. Charity looks around to see if she can see Declan, but can't see him. Declan appears from under the boat. He tries to pull Charity off the boat, but Charity hits him over the head with a small metal suitcase. Declan is knocked unconscious and sinks under the boat and starts drowning. The police start looking for both Robbie and Declan's lifeless bodies. Megan stands alone at the dock, really upset, as the police divers start searching for Robbie and Declan. Charity tells Noah that Declan will never be coming home. The police divers find Robbie's remains but Declan is nowhere to be found. Megan informs Charity that the police can not Declan and that it may be some sign that he is still alive, leaving Charity frightened.
On 9th October 2014, the day of Robbie's funeral, Declan reappears alive having sneaked into Home Farm, where he drugs Charity's drink; she passes out. Using Charity's phone, he sends a text inviting Debbie, Zak, Sam, Jai, Cain, Chas, and Ashley to the house. He makes his appearance apparently holding Megan hostage, where he reveals the truth about stitching Rachel up for the house fire. He makes a quick exit from the house, showing Megan that the gun was fake and that he would never hurt her. He apologises for everything and kisses her goodbye, before fleeing with Sam, Cain, and Jai in hot pursuit. He flees Emmerdale in a car.
Declan is a shrewd businessman who knows exactly what he wants and how to get it. He's prepared to be unpopular if it's good for business and the people in the village recognise his confidence. He does have a softer side but is not the most attentive husband in the world. He is somewhat prone to violence and had anger issues which he took out on his sister Megan by hitting her in the face and the attempted murder of his wife Charity.