Thicker Than Water: The Vampire Diaries Part 1 (2008)

A typical suburban family finds their normal existence turned upside-down when the youngest daughter becomes a vampire, and the rest of the family must kill to keep her alive. Helen Baxter (Devon Bailey) is about to turn 16. She's a cheerleader, a popular student, and the apple of her mother's eye -- essentially the polar opposite of her jealous sister, Lara (Eilis Cahill), a precocious teenage goth. Humiliated by her sister's popular friends at Helen's sweet 16 birthday party, Lara retreats to her room and casts a spell on her sister using a Margie doll and a calf's heart. The following morning, Helen awakens with an unstoppable nosebleed, and Lara realizes the damage she's done when her sister dies in her arms of severe blood loss. Now, as the Baxter family sinks into a deep sea of despair, Lara's neuro-scientist brother Raymond discovers something strange in his dead sister's blood. Helen's blood had been infected with a virus that feeds on red blood cells. Just then, there's a knock at the door. Standing on the other side is Helen. But while she may be on her feet, Helen certainly isn't well; she's drenched in blood, and desperately needs sustenance. Now, the only thing that will keep Helen going is blood, but she was a vegetarian in life, and refuses to partake in the "meals" offered up by her concerned family. At first, Helen attempts to keep her bloodlust at bay by simply ignoring her cravings, but that proves ineffective when she blacks out due to withdrawal and goes on a gruesome killing spree. In order to keep his sister healthy, Raymond starts visiting the local gay bars in search of fresh meat. But how can an upstanding, morally righteous family like the Baxters justify murder as a means of keeping Helen alive? As the family sets out in search of answers to their sanguineous dilemma, the only thing that's for certain is that their troubles have only begun.