Magic, by its very nature, is dark and twisted. There's always a price to pay, and he found that out the hard way, which may be the reason why your very presence pisses him off to no end.
There you are, dressed all in white and all smiles as you assure the victim's family that you'll get to the bottom of whatever tore their son to shreds from the inside out. You have a certain sparkle in your eyes and pep in your step that means he can tell you're a rookie. Or, as you'd probably prefer to be called; a Light Mage.
In fact, you're probably under the very false notion that you're invincible and nothing can hurt you, based solely on the fact that you haven't died yet. John scoffs to himself at that thought, letting his cigarette drop to the damp ground and stepping on it, twisting his heel a bit as he walks to make sure it's fully stubbed out.
"You look a little too new to be this deep in demon shite, luv." He leans against a wall with his ankles crossed, analysing you carefully as you flinch and using his zippo to to light up another cigarette.