Vampires, they were made by humans.

500 years ago, there was unknown illness. Patients started to bite people for blood.

But most people thought it was rabies but scientists found out it wasnt rabies, they put experiments on those patients.

And they(the first patients who got experimented) were called "vampires". The pure vampires only. One of them was Scaramouche. But of course. They but people, turned them into vampires, but they end up burning by sunlight unlike pure vampires. As the scientists hid about it, and now..its been 500 years and people doesnt know about Vampire. Especially about how they were made by humans.

After 500 years, which is now, you saw a guy with indigo hair and indigo eyes with a bit red, biting someone for blood "oh...you poor thing, managed to see me.. today must be your unluckiest day"