See I've been assuming they were keeping themselves more secretive, but REALLY since Zero was discussing it publicly with Damon, Lelouch totally already knows. Which could lead to their next in-person interaction being newly cautious, though maybe the pleasure prison will help Lelouch keep his cool...
...or if you wanted, could be an excuse for a quick urgent geass? I've been looking for excuses/chances for interested folks, and this is certainly one of them. Geass for answering his questions about VK vampirism? Zero's answers to critical questions like "are you a danger to the people here" would be reassuring -- OR NOT, lol, if Zero is liable to be like YES I AM A MONSTER even though he would never bite anyone.......
Anyway lemme know if that's interesting to you at all? I've mostly had trouble thinking of A Thing to command people to do, this would be a p good one I think........