Nothing is know about Harry's life prior to or as the outbreak began, except that he has lived his whole life on Catrina Island, with his family.
Harry is first introduced playing on the beach with his sister as a walker staggers out of the sea. Harry and his sister only notice the walker when it hits a chain link fence as it tries to get to them. He and his sister flee the beach, appearing to be more afraid of getting "in trouble" than of the walker.
Later, as survivors Travis Manawa and Madison Clark approach the house after tying up at the dock, he is the first person out of the house, much to the annoyance of his father. After introductions are made, he is seen in the living room, playing with Madison's teenage son Nick. He invites Nick up to his room. While there, he shows Nick his action figures, all of whom have a red dot on their heads. He tells Nick that it is the only way to survive now and that his family have special "vitamins" so that none of them become infected.
He is later seen coming into the living room to tell his parents that something is wrong with his sister, as his mother is pleading with Travis and Madison to take Harry and Willa off the island. It is revealed that Willa took one of the "vitamins," which turns out to be poison. Travis and Madison take him to the boat with the permission of his father, who remains behind in shock as his undead daughter attacks his wife.
As they are preparing to cast off, Harry's older brother Seth shows up with a rifle and, unaware of his parents request that Harry be taken off the island, demands that Harry comes home with him. As Seth takes Harry off the boat, their now-zombified mother approaches the boat. Seth makes Harry look away as he shoots her.
Harry is last seen on the dock as he stares down at his mother's corpse.