Luke first appears when his uncle Hugo Browning gives Luke's former cellmate Max Branning a visiting order. Max complies and he visits Luke, whereupon the duo discuss their plans to take over The Queen Victoria pub. When he is released from prison, Max picks him up and takes him home, where he is reunited with his sister, going by the name Fi, his half-brother Josh Hemmings and his father James. Luke, James and Hugo discuss purchasing the café and James tells Luke and Hugo he has a better plan for the premises than their idea of studio flats. Luke carries out an unannounced inspection at The Queen Victoria and tells Shirley about the damage. Luke meets Kathy's younger son, Ben Mitchell outside the cafe when Ben accidentally split coffee on Luke's suit. Luke and Ben never knew their identity to each other at first. Luke meets Ben again when Ben is having a drink with his foster brother, Jay Brown and their friend, Donna Yates at The Vic. Ben and Luke end up at The Arches and kiss. Luke, James and Hugo go through their development plans for Albert Square. Luke decides to meet Ben's father, Phil Mitchell and stepmother Sharon Mitchell. Luke left, horrified after discovering Kathy is Ben's mother, when he met her. Ben publicly confronts Luke at work before dumping him. Luke tells Hugo that Ben is Kathy's son.
Luke meets Ben to ask him for another chance. Luke tells Ben he has been released from prison after four years and Ben tells Luke he served twenty months in youth custody for manslaughter. Luke tells James that he and Ben are back together on his request and questions James's interest in Ben and Kathy. Fi promises James that she will get the sealed bids from Max and Luke promises to persuade Jay to sell the car lot land, though Luke doubts Fi's abilities. Luke offers Jay £150,000 for the car lot, which Jay declines, but Luke gives him money. When Jay finds out about his foster father Billy Mitchell is having financial troubles, Jay accepts Luke's £200,000 offer. Luke attends Ben's half-sister's, Louise Mitchell, birthday meal to make sure Phil knows nothing about James seeing Kathy on Halloween, thinking Kathy would tell him. Luke phones James and tells him that Phil is unaware. Kathy confides in Ian that James is back and Ian tells Phil. Phil visits James and realises Luke is James's son when he sees a photo of them. Phil tells Kathy that Luke is James's son and Phil fails to warn Luke off Ben. Ben is angry with Phil for what he did and when Kathy tries to get Ben and Phil to make up, Kathy tells Ben that Phil was protecting him as James raped her. After struggling to process what he is told, Ben is determined to hurt James, but Kathy orders Ben to keep out of it as it happened to her and not him. The next day, Ben confronts Luke with what he has been told and Luke tells Ben that James wants to meet him.
Ben come face to face with James in his office and threatens him with a crowbar but Luke stops Ben from hurting James. The next day, Luke worries that Ben will break up with him as Ben initially decides to end their relationship, due to their parents' history but changes his mind after a heart to heart with Kathy. Kathy is alarmed when Luke grabs her wrist. The next day, Luke is furious with Ben when he plays a prank over salt and furiously grabs Ben's wrist and threatens him before leaving. Donna and Abi Branning witness this and they confront Ben over Luke's behaviour. Later, Luke calls Ben and apologises. Ben finds a business card in Luke's wallet reading 'Project Dagmar' and when Ben asks questions about it, Luke chokes Ben when he demands answers. Ben tells Max's daughter, Lauren Branning, what happened and about Project Dagmar. Josh, who has no knowledge of Project Dagmar, also questions Luke. Luke throttles him before grabs Josh in the throat but Fi breaks them up and Josh is hurt that Fi is in on Project Dagmar whilst he is excluded. Lauren finds a Project Dagmar model, showing how Albert Square will be. Luke gives Ben an expensive car, which Ben orders Luke to remove. Luke physically attacks Ben and leaves him unconscious. James, Luke and Hugo later arrive and James tells them they own Grafton Hill. They serve the Carters with an eviction notice, putting up the money owed to the original amount of £60,000. James reveals that they plan to turn their obtained buildings into luxury flats. When Max proposes to Fi, Luke and James reveal that they have used him as they have doubted his loyalty and burn his cheque.