I'm not sure copyright protects you much against someone continuing a story. Trademark protection might. At any rate, fan-fiction is nothing new and while it m

I'm not sure copyright protects you much against someone continuing a story. Trademark protection might. At any rate, fan-fiction is nothing new and while it might be a bit iffy to do commercially I see nobody even trying something remotely similar without at least the blessing of the original author. So really I think society has decided who is allowed to continue a story and as far as I can tell it has little to do with copyright and everything to do with public perception.