"That's understandable." That was also a lie, he was fairly certain, but whatever the truth was, it was none of William's business. Or, to be more specific, it was only William's business if Jon's absence was because he'd been hiding bindrunes in dusty rooms.
He didn't have any serious suspicions at the moment, so he switched back to the original subject. "I'm not here about the breeding. I'm here because this one..." He paused to hold it up against his robe, so that Jon could see the mottled shift as it tried to blend in with the black fabric. "Does that."