I've noticed this concept coming up quite a bit while I'm editing my novel, particularly with my subplots. I've always called this method "planting seeds," as in, I'm planting just the start of an idea that will be in full bloom later on in the novel (that analogy works, right?). Sometimes I worry, though, if this actually works. By the time that idea is in full bloom, does the reader care anymore?
Example time! One of my subplots in UL involves Jordan's friends, Brian and Eric. Every time we see them, it's brought up how Eric has a crush on a girl, but he never says who she is. At first, it may seem like this is useless information, especially when there are much bigger things going on in the main plot. But later on in the book, who this girl is and how she factors into the story are much more important. She's not so important early on in the book, but when she actually does show up, I'm hoping that it's not so random because I've been hinting at her all along.
I've done something similar when it comes to certain character details. Maybe one character doesn't want to reveal something about himself, but since the idea has been brought up, eventually it has to be explored. Or, another example, there's a certain detail about Jordan's mother that he keeps secret from the reader, but later on in the book, he's forced to reveal it to another character. I've tried to drop hints up until this point but really spent a long time avoiding it (but on purpose!). When it's finally revealed, we can look back and think, oh that's what he was talking about!
Basically what I'm trying to accomplish is to just have a moment where the reader should think, "oh, ok, this will definitely come up again later!" Even if it's not necessarily important to the plot right at that moment. But my hope is that planting these seeds will make the moments later on where the idea is actually relevant not so out of nowhere. Hopefully the reader will believe it because they at least knew something was going to happen.
The thing I worry about is whether the reader will notice or even care when these hints are dropped. Or maybe when the real idea is revealed, they'll think back on all of those hints that went over their heads.
Do you plant seeds early on in your stories?