Deborah Harper is an attractive twenty year old student and Helena's younger sister of four years. Compared to her serious sister, Deborah has a more carefree, playful attitude. Having already lost both parents, Helena is incredibly protective of her only living relative, and she has previously shot and seriously wounded one of Deborah's former boyfriends after a difficult breakup. Her actions caught the attention of presidential aide Derek C. Simmons, who then abducted Deborah in order to force Helena to assist in his terrorist scheming. Deborah was imprisoned in the laboratory beneath the Tall Oaks cathedral, and although Simmons should have released her once Helena had done his bidding, the infatuated lab researchers used her as a C-Virus test subject. Deborah left a note for her beloved sister in the laboratory moments before she lost consciousness.
Deborah is found abandoned at the first altar beyond the underground laboratory, but she mutates into a creature before Helena and Leon are able to escape with her. While she retains vestiges of her former beauty, she loses all sense of human reason and attacks the pair with the claw-like tentacles that emerge from her spine, leaping overhead with incredible agility. Although Helena initially refuses to accept her sister's fate, she ultimately allows her to slip from her fingers to her death, vowing never to cry again until she is avenged.