They were patrol partners who once shared the classic buddy cop relationship. In fact, John would go so far as to say they were his only friend on the force. About a year ago, he began obsessing over the town's conspicuously long list of missing persons reports and other grisly unsolved mysteries. It was something for which he caught a lot of ridicule from his co-workers. Your character tried to be supportive, but after a bad anonymous tip which led to wasted man hours and culminated in John's injury, they joined the chorus of concern in lobbying for John to be placed on administrative leave pending an evaluation by a police psychologist. John considered this both a betrayal of their friendship and proof that there's a dark secret the department is actively working to cover up. More detailed information can be found in his bio.
I would like to explore the dynamics of a friendship wherein the bonds of trust have broken. Possibly friends to enemies depending on how things develop. The gpsl this line is for deals in supernatural themes, and if your character knows the truth behind the disappearances it could be that they conspired against John to spare him from a terrible fate. I have no strong preferences when it comes to pbs. Their age, race, gender, and everything else is for you to decide. So long as they're old enough to fill the position, whoever you want to use is fine.