Tony discovers the affair of Ste and Harry, which shocked his stepmother Diane and finally discover why Sinead left Hollyoaks forever. In November 2015, Harry finally comes out to his father, and accepted his sexuality, and his relationship with Ste. On his 18th birthday he discovers that his godparents Ruth, Jambo and Rory and his mother couldn't attend to his 18th birthday, as he discovers that Jambo refused to return to Hollyoaks since the death of Dawn Cunningham in eighteen years. Later that day Ste tells Harry that due to his HIV he now has to go on medication, but Harry accepts it. Ste later breaks up with him that night anyway after being manipulated by Tony who refuses to believe Harry's gay. Harry later sees Cleo holding hands with her step-father Pete and she accidentally lets it slip she was having a relationship with him for years. Furious Harry storms to the Dog where Reenie and Pete are having their wedding ceremony and publicly outs him as a pedophile. On Christmas Day Harry finds out that he was accepted into a football scholarship in California. He then discovers that Tony had called the police on Ste for doing drugs in order to wreck their relationship. Harry then packs his things and leaves saying Tony was the worst father ever and he was sick of Tony trying to control him. He is shocked however to see Ste about to reunite with John Paul and runs off heartbroken. He then returns to Tony's as he has no where else to go, but Ste comes and says Harry's the one he wants and Harry agrees to give them a go. When Tony protests Ste invites Harry to live with him and Harry agrees. They spend Christmas together with Leela Lomax, Tegan Lomax, Ziggy Roscoe, Peri Lomax and Cameron at the Dog.
Harry continues to date Ste, but the relationship turns turbulent when Ste gets kicked out of the Lomax's and Harry goes with him after Cameron Campbell frames Ste with some drugs that he found in the house. Harry then has sex with James Nightingale after being put under pressure by the older man. The money, however, was not needed as Leela and Tegan give Ste a second chance. They then lead on to break up as Ste discovers that he slept with James. Set ends up becoming addicted to crystal meth after Cameron gives him some, and Harry and Ste get back together in that period of time. After originally going to leave for France, Tony decides to stay behind in Hollyoaks to help Harry get Ste over the addiction. After the first night, Tony decided to hand Ste over to doctors who will be able to give him real help.
In March 2017, Ste and John Paul McQueen finalize their divorce. The next day, John Paul and Ste sleep together. James finds out and gets revenge on John Paul. John Paul then goes to tell Ste he loves him when Ste proposes to Harry, resulting in John Paul's departure from Hollyoaks. At Amy Barnes' and Ryan Knight's wedding party, Harry discovers Ste's affair and dumps him. However, Harry forgives him and they get back together right before Ste is questioned by the police about Amy Barnes' death.