Magnus noted the pause, how Billy opened his mouth and then shut it, but he didn't take too much by it. He didn't think he had said anything wrong; his words were perfectly innocuous. Perhaps Billy thought to press and ask for details, beg for some more instruction, but there was no point, really. Magnus was no better armed to deal with this with his own Lightwood than Billy was.

He nodded and clapped Billy on the shoulder. "You'll be fine," he promised. "And for right now, you can enjoy your party. I think the fact that Isabelle decided to throw one is a very good sign, even if she is in white."