Obviously vampires don't exist in the real world. There are no fanged immortal creatures out there who burn in sunlight and die if they don't drink blood. That doesn't mean, however, that there aren't people out there who wish they were vampires. They can't live forever or grow fangs at will, but they can totally cover the blood drinking part.
Take this real horror story, for instance. When James P. Riva was 23-years-old, Riva murdered his grandmother. Then, he opened her heart so he could drink her blood. He did this because he thought he was a 700-year-old vampire. He thought his grandma was a vampire, too. According to him, she'd been drinking his blood while he slept... during the day... in a coffin... I guess. That part's unclear because he burned the house down afterwards.
