Alright, we will see then. I... really can't see Joseph initiating that kind of relationship. The reality of his station prevents it. He can never have a truly equal relationship with someone not of his station. Even if he fell in love with Mois, he would never reveal it, except maybe in circumstances like you described. And even if he did, he would not want to form a relationship because he doesn't think that it could ever be healthy. His position does make him very alone, however. He can't fraternize with other slaves either because his rank is above theirs. 

Quite apart from all of that, he's sort of like a father to them, so that's makes things a little strange as well, dating someone that you still remember changing their diapers... though I suppose age difference makes less of a difference in vampire stories.