Blood Alert — Arlene Webb

Born with a strange addiction, Cham needs a pint of blood on a regular basis to stay alive, healthy and solid. To make a miserable life worse everyone around him, except for his sister Kylee, overlook him as if he's not clearly there. But when he is the center of attention, he's learned the hard way never to speak of things no one else can see.
Kylee's mother died giving birth to her brother when Kylee was four years old, and leaving them in the care of a bitter and angry father. From the moment Cham's fingers clutched hers, Kylee's been determined to protect him from the visible and invisible monsters. After fleeing an abusive home, their lives revolve around stealing what he needs to survive.
When Cham confides in her about a man from their past no one else could see, Kylee refuses to leave him or let him fade into insanity. All is fine in their little world, until the cops arrest her for theft, and hallucinations do much worse than torment Cham's memory. They become so violently real, the siblings wish it was as simple as throwing him in a padded cell.