As if Sherlock isn't usually a real person. John gets what he means, of course, but he'd hardly call it a real person if it's just pretend. He much prefers what he gets to see, in that case, he's very certain. But, well.

Other people, and whatnot. That it's apparently unusual.

"Yeah, all right. Wouldn't have been that hard to work out." He can give Sherlock that much. But, moving on. "So. Alternative routes to Hogsmeade."