Is Mois really right about Alexi? That he doesn't even trust his own brother? I interpreted it that Alexi is just trying to protect him. I mean, if he knew Erik was free to just wander around the room right now, he'd freak.

If he is right, that's a scary thought. Trust shouldn't come from doing someone's bidding all the time. If the only person he can trust is a slave who has little choice but to do as he is told, then that is a sad state of affairs indeed.