"They appear to be ordinary mortals," said Crocell, "with no magical skill at all – magical blood must run stronger in you for some reason. How interesting! My kind are hidden from their perception. Watch." He poked her father’s arm with one sharp-nailed finger, and her father absent-mindedly brushed his sleeve as if to remove a bit of lint, not noticing that he pushed Crocell’s arm away in the process. When Crocell moved as if to walk straight through Emily (while Hermione worried they’d crash into each other), she stepped to one side, as if she coincidentally felt like moving. Emily wandered away to tidy up a small pile of books on the coffee table.