Sirius let himself remain still even after the knife was set down again he wasn't eager to have that come back into play, even if something like that was hardly a threat to a wizard he didn't relish the idea of fighting anyone, especially over something like a misunderstanding. So he stayed where he was, letting Will take his time to process what he'd just seen and been told.
He gave him a sort of apologetic look when Will repeated the word Magic, there was really no true apology one could make for magic, it was all he knew of course, but he was fully aware that here in this world it was not the norm and facing muggles with that fact could be a lot to deal with. "It's a lot easier." He agreed, "Sometimes it's really the only way to make it through a day." He admitted, lifting his shoulders in a slight shrug.
He huffed though when Will asked him about the food, giving up on trying to truly understand the magic and all of this. "It was good," He grinned, "Better than a lot of what I've eaten at times like that." It was the first time anyone had ever fed him like that, but a lot about this hotel was made up of firsts. "You do that for her every day?" He wondered, curious.