Because whenever she was by his side, he rarely ever looked away from Lenalee. So he knew so many of her quirks and body language he would probably be only second to Komui though when it came to intimate details, he was the undisputed king of that knowledge.

"Mmmm if this was a perfect world I would love nothing more than to have that happen~ Hearing you like that would be a dream come true~ Lenalee~" He just had to be ruthless and call her name oh so sweetly on top of it all.