Debbie Clarke was the presumed sister of Polly Clarke and is the daughter of Louise.
Debbie was a rebellious school student, who was friends with Stacey Barnett and Lauren, as well as very close friends with Josh Jones. She often fought off the advances of Lennox - mostly because he would bully Josh for being gay.
Debbie met Tank Top at a club, but he was shocked to discover that she was a high school student, and left her. Debbie soon discovered where Tank Top lived after his roommate, Adam Tyler, invited a "homeless" Josh to stay with him. Tank Top realised that he had feelings for Debbie, and, although their relationship was rocky, they got together.
Debbie was distraught when a woman, Louise, turned up suddenly at her flat, claiming to be a social worker. She showed Debbie her birth certificate and Louise told her of a birthmark that she had. Polly was forced to tell Debbie that alcoholic Louise had given her up as a baby, and the care home workers suggested that Polly act as an older sister to an introverted Debbie, due to having the same surname. Debbie began to resent Polly and told her that she never wanted to see her again before leaving. Polly then committed suicide by overdosing.