@sick of Life they are related dude, by half, see, Cayena is the daughter of the empress, so is Rezef so it is totally incentous if they end up together but I doubt that. Basically Rezef is the half brother of Cayena through the Empress/Queen and a half brother to Raphael through Raphael's father (the now divorced duke).
I stan for Cayena and Raphael... but these people are so da** gorgeous da**!