Season six of American Horror Story has actually introduced very few characters — the trick is that two people are playing each of the main characters. Roanoke (so far, at least) has presented itself like a true-crime show, wherein a few people are describing their experience with the supernatural interview-style, set up in front of a camera. Then the show cuts to a dramatic reenactment of their story, complete with actors playing their parts. In case that's confusing, here's a rundown of who each person is playing and who is playing them within the world of the fake show.
I wish I could tell you who plays the reenactment version of Rhett, but he's not even listed in the credits.