Bleed by Ed Kurtz
When Walt Blackmore moves into an old Gablefront house on the outskirts of a small town, things are really looking up for him "he has an adoring girlfriend, a new job, and an altogether bright future. But Walt's destiny is irreparably changed when a dark red spot appears on the ceiling in the hallway. Bit by bit the spot grows, first into a dripping blood stain and eventually into a grotesque, muttering creature.
As the creature thrives, Walt finds himself more and more interested in fostering its well-being. At first he only feeds it stray animals, but this soon fails to satisfy the monster's ghastly needs. It is gradually becoming something more, and for that to happen it requires human blood and human flesh. And once Walt has crossed the line from curiosity to murder, there is no going back.