According to his Bravo bio, John is originally from Charleston like most of the stars of the show. He didn't meet Shep until they attended the University of Georgia together, but they remained in touch. After college, John found himself in New York City and, eventually, Los Angeles, where he worked on a music career while also growing a family with his now ex-wife.
Being back in Charleston by way of Southern Charm is John’s way of getting back to his roots as a seventh-generation Charleston resident. He also has two sons who he seems to adore, but co-parenting with his ex and being on the show might make the transition a little more difficult for him. Cue the inevitable drama.