"The 'who' would be a fair long list," Little John said, cautiously. A long list, and quite possibly an overwhelming one... Perhaps best to move on past that, for the time being. At least till he had some sense of how they might react to finding out things like, Santa is real. The devil is real. Yeah, best to approach that one gently.
"I suppose the difference might be in the lasting impact a story makes on a culture. Take mine, mine's layered and layered over several centuries, a band of fellows stealing from the rich and giving to the poor has always been something people have needed, there's a lotta hope in it, a fair amount of wish fulfilment that's as true today as it was back then, guess that's why we've stuck around. But parameters? Hm. I suppose when you get down to it, it must be measurable," he acknowledged, getting the impression that Rosario needed to hear something of the sort. "Number of people who know your name? Degree of belief, rather than quantity?"
"Strength of conviction?" Lyra asked, thinking about Avery. "Like if someone believes enough in a thing... It's real?" She shot a look towards Rosario, all wide eyes and dramatic brows. How could you believe things into existence, though?! This was backwards, surely this was backwards?
"Lots of someones," Little John said. "Lots of someones for lots of time."