"Hmm." A demon taking the shape and mannerisms of Luna kind of unsettled Merlin a bit. Surely he would have sensed if it had slipped into his home? But no, no, it was definitely his Luna who came to (for) him every week. At least she was safe. He'd miss her while she was gone, though.
"I have been researching exorcisms and protective sigils," he said, nodding towards an open tome as he made the tea. It was on what looked like a ferris wheel for books, each tray supporting a book open on a different page. "Feel free to peruse. Do you take milk or sugar?" He took an internal guess at no milk, two sugars, but he wanted to see if he was right before he asked.