A Drop of Haunted Blood

Felix can communicate with the ghosts bound to his blood and use the magical abilities they wielded when they were alive. His newfound power would be pretty cool, if the ghosts in question weren't his family and the man who killed them. Death doesn't stop Felix's siblings from finding new ways to annoy him from beyond the grave, nor his parents from doing their best to protect him. Felix learns that his family belonged to an organization of magicians called the Bright Guardians, while their killer was a part of the uprising that tried to overthrow the organization eight years earlier. The Bright Guardians take Felix in, hoping they can train him to fight monsters and control the ghosts inside of him.