Ok, I’m the first to admit that I am a series junkie. I rarely pick up books that don’t have “Book 1 of blah” at the top. I love the feeling of total immersion you get from a series. You really get to see the wonderful world and people created by the author, and since it usually takes years for a series to play out, you have an ongoing treat for a long time. (This excludes those books for whom the author over stayed their welcome- some series have gone on waaaay longer than they should have. But that’s for another post.)
This obsession with series flows over into my writing. All four of my currently completed books are series. Now all four can also stand alone, but all of them have further books in my head and in various notebooks. Two are more trilogy based-aka- the big arc would be resolved in a total of three books. The other two are open ended series. Meaning that while the main adventure for book one is resolved in book one, there are plenty of further adventures in store. In both types of series I’ve got hints to the other stories- little bits of information that when the next book comes out will make the reader say, “OH! I remember that!” In a way it’s akin to planting the gun in chapter one that the killer needs to use in chapter four- only longer range.
For example, in my steampunk book one of the minor villains is tracked deep under water at one point, then later found with certain issues that indicate a time spent exposed under great depths of water.
Not alot is said about it, he’s a minor villain. But it leads directly to book two Jand a very large sea based threat that my heroine and hero have to face.
Since my main characters run through the entire series, they have secret plants/hints as well. As they go through their adventures, there are hints dropped that they may not be what and who they thought they were. Sometimes this is a good thing, sometimes it’s very very bad. But the point is, there are hints. Even though who they really are may not be part of the arc of the first book, there are enough hints there that when more is revealed in future books it’s not a shock. I hate it when an author pulls something major out of thin air that wasn’t in a previous book, then acts as if it’s part of the main story. The whole point of unveiling things is to entice the reader, but also to make them see how the pieces fit.
A word of caution about planting hints. If you plant them, they need to lead to something. This is true for long-term plants (things for future books) and especially true for bigger ones you use in a single book. If you as the writer focus on a certain action, event, type of shirt, whatever- I as the reader will think it’s important. When the author doesn’t do anything with it, then I as the reader get vexed.
Unlike real life where unconnected things happen all the time, there has to be a connection between everything you show your reader. And even everything you hint at.