The knock at the door surprised him and Remus shot a curious look at his lover before he moved to answer it. He hadn't broadcast his move to the rest of the staff for all the aforementioned reasons of wanting his privacy in his quarters and 'business' in his office. Other than Regulus there was only one other person he could imagine even knew about it.
And he was fairly certain that person would not be paying him a social call on any night.
Of course, he thought after opening the door and seeing that person on the other side, that doesn't mean this is a social call.
"Headmaster," he said politely, if not warmly. "Please, come in. Is anything wrong?" Because, really, if something wasn't wrong, he couldn't imagine what Severus Snape would be doing at his door on a Saturday night.
Unless it was just to put a flaw in his nearly perfect day.