So you have come up with a wonderful idea for a novel. You have it all planned out. You know every detail of what is going to happen with your main characters. You know what plot twists are going to throw your reader for a loop. You're set! Then you start writing and find a huge problem. It isn't enough. Your plans for a novel have resulted in a short story with dreams of growing up into a novel. You add more details to your characters, embellish a little on the story, and even get creative with your spacing. Still not enough. You need a side story. Where are you going to come up with a side story? You fried out all of the creative circuits in your brain imagining the main plot. It's all over! The book is ruined! Time to go back to watching Star Wars way to much and living off of popcorn! (Not that there's anything wrong with that!) Before you format your hard drive and burn your printed copies, you should realize that a side story isn't that difficult to create, and it can make a world of difference in your characters realism. Think about it. Do you do only one thing all of the time? Even people who are obsessed with something take a break from it now and again. Your characters should, too. That is where a good side story comes in. It transforms your characters from characters into people. So where do you find a good side story? My suggestion for that would be the same suggestion that I give for most things. Open your eyes! The perfect side stories are all around you or have already been a part of you and your life.
One of the favorite approaches I have seen some authors use is to make the setting of the book a side story. That is a tried and true technique. It's especially useful if you are very familiar with the setting yourself. When this happens, the setting becomes a character all its own. Could Batman take place anywhere other than Gotham City? I really enjoy the Dresden Files series. In it, Jim Butcher often uses the setting of Chicago as a source for side stories. He takes common sites in the city and twists them to fit into his paranormal world. You can certainly do the same.
Of course, everyone doesn't want to use the same formula for creating side stories. That would make for boring literature. So what else can you look to for side stories. Think of your own life. I don't mean that you should make every story a biography. I mean that everyone can look back on an event in their life and imagine how it could have been different. You can positively or negatively change how things are handled by your characters in the same situation and create a good side story that will be very believable. After all, the situation did occur in real life, right? You can also look to your own activities. Why not incorporate some of your own hobbies, your job, or some of your interpersonal interactions into side stories. Once again, reality creeps into fiction, and it makes for a better story.
So, if it is big cities or family reunions, career moves or airsoft games, you can find lots of ideas for side stories for almost any book. Just look around, remember, go through a photo album, or talk to a friend. Personally, I am using airsoft in the book I am working on now. It gives me a good side story and an excuse to go and play!