For your erotic scene to be integral to your plot, it must do at least one of these things;
Cause your character to question him/herself and/or change in some way
Change the relationship between the characters
Further the story – come closer to the resolution of the conflict
Alternatively, throw a spanner in the works by creating more conflict
Reveal something new about the characters or the story to the reader
For every erotic scene, ask yourself; what are the characters motives, what is the outcome, and how does it further the story’s development? If these have clear answers, then your sex scene is feeding the plot.
Motives
Why are your characters having sex right now? People have all sorts of motives for having sex, from love to curiosity to impending danger to a sense of solace, but whatever the motive, make sure there is one, and your story people aren’t just having sex because you’ve reached a lull in your story. Or just to arouse the reader.
If you’re struggling to pin down a clear motive, ask yourself – and your character – the following questions;
What has just happened/is about to happen that could throw sex into the mix?
What are the underlying tensions?
What emotions are being experienced? What emotion is your character trying not to experience?
What’s the setting? Is the location particularly enticing?
What does the character want to change about their current situation?
Outcomes and development
Whatever your characters’ motives for getting it on at that precise moment, it’s the outcome and subsequent plot and character development that will have the most impact on your story. No matter how compelling your characters’ motives or even how hot the actual sex scene, it will seem superfluous if nothing happens in your story as a result.
Strangely enough this is often harder to do when writing within the erotica genre, as it’s a given that the character is going to be having lots of sex. If you’ve got, for example, twenty explicit sex scenes in one novella then it’s relatively easy to lose track of the story arc and forget to make every encounter count. The impact can be subtle of course; your character doesn’t need to have a life-changing experience every ten pages, but every erotic scene should contribute to her development in some way, even if it’s as simple as her discovering a new sexual like that she resolves to bring into every further encounter. Or she has the best orgasm of her life and consequentially compares every encounter to that one. In my BDSM story ‘Wicked Games’ for example, whereas some of the erotic encounters between the couple have dramatic outcomes for their relationships and lives, others show a subtle unfolding of sexual exploration. But there is always an impact.
If you feel it’s the right time in your story for a sex scene but you’re not sure what the consequences will be for your story and your characters, then ask yourself the following questions;
How does your character feel about the encounter? Regretful, exhilarated, loved up?
Have the character’s immediate or future plans changed or been altered in any way?
Does the character want to repeat the experience?
Has their sexual knowledge or repertoire been expanded or altered?
Whether subtle or explosive, as long as the erotic encounters in your story have clear motivation behind them and a discernable outcome, then you’ll be able to ensure they are tightly bound to your overall plot.
Exercise; recognising motive and outcome.
Take three stories that have at least one erotic scene in them, some highlighters and something to take notes on. Read quickly through just the erotic scenes and see if you can discern for yourself what the characters’ motives are and what the likely outcome will be. Then, read through the scenes before and after and see if you were right. Determine what the actual motives and outcomes are and how the author has portrayed this. Read ahead a little and see how the encounter has affected the story. Do you think the author has done a good job? Would you do things differently? Do this with each story and then compare and contrast them. Which author has in your opinion used their sex scene most effectively?
Extract from ‘Passionate Plots; a Guide to Erotic Stories and Scenes’