Bloody Lover

Harry Styles; a handsome blood splatter pattern expert 23 year old man who lives in an average house with his 5 year old girl, Kolbie. He seems like the average man, but he has a bloody secret.
Harry kills people. Guilty people, ones who deserve to die (In Harry's mind).
Then there's Louis Tomlinson. A 22 year old private investigator who is very smart and sees things everyone misses.
When they're out on a crime scene Louis makes an effort to talk to the curly haired lad, and successes. Him and Harry become close. Too close, it's at the point where they're living together. Harry wants to keep Louis and his loved family safe. But, they get in a fight about Harry's feelings and the lad gets frustrated and reveals his secret. Louis magically ends up staying the night. In the morning Harry wakes up to an empty house and a note from Lou.
Now Harry has to track down his own love and daughter.