That sounds awesome! Also, the person who's going to play Lucia said something about maybe having a connection with Will, like perhaps Cameron (his former owner) owed the Vargas money, so if Duncan is friends with Lucia then maybe that's how he finds out about Will's position. We could say that Cameron's helots were taken because of something relatively minor, like operating a brothel without a license, and hasn't yet been charged with abuse/neglect at all, and maybe Duncan wants to rectify that. Also if he's familiar with these kinds of cases (sounds like he would be) he would know to expect a lot of the psychological issues that Will has. (Will has PTSD, but it's undiagnosed.)
As far as Brandon goes, I was hoping you'd say that! I totally agree. Brandon is a very complicated character and a hard nut to crack. I played him elsewhere for over a year and let me tell you, I was still only touching the tip of the depths there. He might be the best character I've ever written if I'm honest. Anyway, when Duncan meets him, Brandon is dealing with a lot of self doubt, depression, anger, etc. He has trouble making decisions on his own at this point. Some days he's desperate for someone just to give him some guidance to relieve the pressure on him, but at the same time he feels like he can't ask for it. Actually he has trouble asking for anything. But on the other hand, he's smart and sweet and loyal and compassionate and funny, and he's unfailingly obedient once someone actually takes control. (whether that's because he wants to be or because he thinks he has to be is another question....)
We can definitely explore sex between them too. Brandon is pansexual, and although at the moment he isn't feeling a lot of sexual desire towards anyone, if Duncan were to make sexual overtures Brandon would be receptive for sure. Actually, once he knew it was an option, he might seek it out as a way of getting someone to dominate him. (He's also been known to act out on purpose when he gets desperate just so that someone will punish him, because then at least they're taking control.) Honestly I can't be sure how things would go for him sexual, because it could be good or dramatically bad. But either way it'll be fun to write!!