Harry blinked. "Oh!" he said in mingled disappointment and relief. Not his dad, then. He was extra glad he hadn't actually got the question out - that would have been really awkward and embarrassing. But they were related then probably, with the same last name, maybe an uncle or someth-
He hesitated, frowning suspiciously. "How... do you know I'm a Potter?" he asked. It made him quite uncomfortable how everyone in the wizarding world seemed to know who he was when he didn't know anyone at all.