Why Each Character Has Joined the Cult on American Horror Story (So Far)

This one is by far the most mysterious. Detective Samuels is a man of few words. He's obviously in the cult to give a direct connection to the police and to corrupt the law enforcement in the city. As for why? Beats me. We know he's sleeping with Harrison, so maybe that's why he decides to join in. Other than that, he hasn't given us much to work with.