Say you're a vampire. 
Your best friend dies in a car accident. You are with him. The drunk driver of the truck who hits you doesn't die. 
You're badly hurt. There's only one way you can heal yourself. Your friend is dead. His blood will not help you. 
Your best friend had a prophetic dream about the accident and his subsequent death. He did not tell you about the dream, or tell the rest of your friends. 
He contacted his sister, who has the peculiar talent to bring the dead b...