John Constantine is an occult detective from Liverpool, England. His violent and anti-social attitude makes him a formidable anti-hero, and he's known for doing whatever it takes to get the job done.
During his childhood experiments with magic, he attempted a spell taught to him that would make him a powerful magician. However, he was not told that the spell required a sacrifice; while performing it, his family home caught fire and resulted in the death of his mother and father.
In his young adulthood, Constantine was a wild, silver-tongued punk with no idea what he was destined to become. Though he had a knack for being a conman, Constantine had continued show interest in anything of the occult, but did not take it past a hobby until he began a relationship with police officer named Margaret Ames. The two bonded by going on amateur magical adventures together until Constantine decided she deserved a normal life and left her without explanation.
Later, Constantine and his first love Veronica Delacroix formed a mystical-themed punk band named "Mucous Membrane" with their friend Gaz Lester. The three lived the rock star lifestyle and began getting more serious with the magic they practiced together until a spell went terribly wrong, causing Delacroix to slowly lose her connection to the mortal world. Constantine was unable to stop it and the band, in turn, fell apart; as a result of this incident, Constantine became determined to focus on his skills as a magician.