Ivan Askwith (currently the Senior Director of Digital Media at Lucasfilm) is a leader in the New World of storytelling for a reason. For example, here is a Jan. 26th, 2010 blogpost written by Ivan (back when he was working as Big Spaceship) that explodes the myth - still prevalent among digital marketers and their clients - that "viral" is "a specific type of work that marketers can choose to create, rather than the resulting pattern when people choose to share something with each other."
Here's what Ivan wrote (with a nod to Prof. Henry Jenkins of USC) back at the start of 2010: "As Henry Jenkins points out, viruses are transmitted whether their hosts wish to share them or not; they can’t be stopped, and the participants are helpless victims. Content, on the other hand, is only shared through intentional decisions. Unless consumers have a strong, personal motivation to share with each other, nothing gets passed along to anyone. If we want people to share things, we need to stop thinking in terms of “viruses” and start thinking in terms of “gifts” — things that people choose to give for specific reasons. "