The Murder and the Curious Writer

Lucy Heartifilia is a detective looking for justice. For sometime now people have been mysteriously killed. All Lucy wants to do is get this guy and put him behind bars.
Natsu Dragneel has been working with Lucy for a while. But lately he has been feeling weird
Mavis Vermillion is an author looking for a new story. When she learns of the killings in Magnolia she knew it would be her cure to her writer's block. However this was not what she was expecting.
Zeref Dragneel had turned his brother into a vampire to keep from losing him forever. However turning him into a vampire caused him to forget his memory. And now there were a lot of people getting killed. He had to find his brother before something bad happened to him.