This is a entry for the seventh sanctum contest [link]
I feel kinda bad that I didn't spend a lot of time on it. Any ways here is a little background. Nathaniel Nix was born in a small town. His mother was a vampire while his father was a human. Since he was part human, he could be fed fresh cow meat for all of his childhood and part of his adolescence.
Nathaniel was a quick learner. He loved school and enjoyed learning. He enjoyed most of his studies (except history, for it was all about humans.) His school started teaching Biology when he was in 3rd grade. This truly fascinated him. He learned about evolution and how everything had a common ancestor, making him interested where vampires fit in.
Once he started taking chemistry in high school, learning how everything was made up of basic building blocks called elements, it only peeked his curiosity more. He started to wonder why vampires could only feast on human blood. The only theory he could come up with is that human blood is very consistent with types, which are all edible. Horses can have 30 different blood types, making one wrong decision fatal, as certain blood types are toxic.
Beef wasn't sustaining him any more and he would have to start drinking human blood. He didn't like the prospect of being a murderer, so he studied. After days of starving and hard work, he finally completed a replica of human blood. He began to mass produce and give away to people who needed blood transplants.
Now, at the age of 22, he runs a small shop in his home town that sells his concoction as a drink called "Blood Rush". He has all types except "AB" which he still can't figure out. Vampires from across the world come to his shop for a drink. There have also been instances of humans buying it, mistaking it for an energy drink.