I’ve heard writing teachers say that you should avoid subplots for your first few novels. What? We don’t get to play in the full sandbox? I don’t think I’ve ever written a book without a subplot or a bunch of ’em.
Subplots are story lines in addition to the main one. They often feature a different point of view character, but not always. For instance, if your detective falls in love, he may pursue his interest in a way that needs a new plot thread.
When to use subplots
The decision may depend on your story’s complexity. When the breadth or depth of your story may suggest that you’ll need more nuance to express your theme and/or deepen audience experience. Epic fantasy, for example, may gain breadth from subplots. Or the story needs to feel especially substantial because of the sweep of its plot. Another case is one in which the world needs the perspective of more than one through-line to be fully revealed. Or your story has a profound theme that can benefit from a mirror-story, or a counter-point story. That is, you want to underline your theme by proving your thesis in more than one context or you want to shade the meaning by offering a contradictory example.
Subplots can bolster the main conflict. Sometimes the main conflict needs more tension than can be reasonably found in the main story events. (Warning: this is a good reason to reexamine your concept!) A subplot can offer further conflict to your protagonist’s goals.
It may fill a structural gap. A long middle–an Act 2, if you like–may be taxing on the patience of an otherwise engaged reader. A subplot allows you to weave in another inciting incident and climax, possibly all within Act 2. Add in reversals for the subplot, and suddenly the middle of the story is keeping your reader awake at night. And at its simplest level, subplots can give us a welcome rest from the relentless momentum of the main plot.
When to skip subplots
Don’t use a subplot–not that you would–in order to spend time with a favorite supporting cast member. As interesting as that character may be, his or her story is in harness to the main plot. It is most useful when it augments the central plot in one of the above ways. Don’t let a great minor character run away with the story. She might be quirky and deep, but she’s there for the main plot or you’ll have to kill her. (And speaking of killing off characters, killing the POV character in a subplot is a nice reversal.)
You don’t need a subplot to show things outside the viewpoints of your major characters. Giving POV to a minor character for needful story information can be done without creating a story line of its own. Of course there are many ways to report information from off-stage. The choice to create a subplots should be more substantial than convenience.
Aside from these larger issues, here are a few guidelines I use:
Make sure the subplot relates in some way to your story’s premise, or it will fracture your novel, destroying its unity.
Try to connect the subplot with: characters who inhabit more than one plot or have shared goals or a close relationship.
Don’t let a subplot upstage the appeal and empathy of your main story and character. It seems wrong and unfair, but a reader’s allegiance can be siphoned away by a riveting subplot such that they are disappointed to return to the main story.
Provide structure to your subplot; give it it a rising action and a climax just like the main plot. (Usually place the subplot climax before the main one, so as not to upstage your main scene.)
You can have some fun with subplots. Give yourself and your readers a break; try some humor or over-the-top characterization.
There are stories that are multi-plot. “Crash” with Matt Dillon is a film example. If you’re writing one of these, you’re not really using subplots, and you’ll be operating in a different context.
A last caveat. I’ve heard editors say that they prefer novels with no more than two subplots. Otherwise they feel you are over-stuffing the story. I routinely ignore this advice in service of big novels. But if you’re just starting out, you might want to bear this caution in mind.