If you want to tell the story of the time Jon Jones became the youngest champion in UFC history, you have to start with the dog. Its name was B.J., a seven-month-old German Shepard mix, and it was a somewhat recent acquisition for Jones when he showed up in Newark, N.J., for his crack at Mauricio Rua ’s UFC light-heavyweight title on March 19, 2011. The kinds of places Jones was going that week – fancy hotels, TV show sets, hotel ballrooms converted into UFC workout spaces – are probably not the sort of places where you’re supposed to bring your dog. Still, there he was in the lobby of Penn Station Hilton on St. Patrick’s Day, dodging fans and drunks and leading this dog around on a leash, smiling like a man who was enjoying the extra privileges that come with being a star, confident that no one would dare tell him he couldn’t bring a dog in here