I know unpublished authors shouldn't really think of doing a series right away, and I understand that if they do, they need to make sure the first book is very standalone. However, I have been working on a fantasy idea for a while that goes beyond a single book, and it's built around a group of villains, and the easiest way to construct the series, then, is to have each book focus on a specific villain that the protagonists have to fight. The problem is that the back story of the villain in the first book includes the other villains. They're all connected, so I can't simply rearrange the order of the villains, and it would be difficult to separate one from the others. So, my only solution is to leave some hints at the end of the first book that there are more of them out there, but somehow still keep the story self-contained. Anyway, my questions are: Do you think that if I mention the other villains that it immediately becomes less standalone, and will publishers read that and think "He's planning a series, so let's not publish this", even if I'm trying to make it as standalone as possible? How do you think I can suggest more stories, without losing the self-contained story of the first book? Do you think I should simply set this story idea aside until I already have something published, and focus on an idea that isn't a series? Then the series idea could be a side project? I know it might seem a bit silly to think about a series this soon, but I would appreciate any help. Thanks.