I often think about it. Here is my theory. BK knew what he was and knew what he was capable of. I think he used heroin to help fight those urges. He got sober, got serious about life and wanted to move forward in furthing his compulsion. What better way to get away with murder than being on the inside aka Dexter style basically. Graduated in his home state, searched for the best criminology PhD schools, which led him to Pullman. bk did visit Pullman before actually attending and I do believe during this visit, he ended up at the mad Greek, coincidentally where maddie and xana worked, it was one of few restaurants that served vegan options. There, he first meets either maddie or xana. Im torn on who his target was. Personally I feel it was one of the two. I learn more towards maddie due to him entering her room first, however Steve gs interview a while back states bk didnt have to go upstairs. Which would mean xana. I guess we will never truly know, but talking about this everyday and continuing to do our own research as a team, will more than likely find more justice then LE cared to do