During the conservative era of literature, the depiction of sex was considered taboo and was better left in the sanctity of the bedroom. But times change, and defiant writers believed that sex as a natural, biological function must be depicted. Otherwise, all things that come naturally like food, shelter, and clothing might as well pass under censorship. Literature has evolved with the mores of the times. Now that the world has become more open-minded to the concept of intercourse, a plethora of sex-themed stories continue to take a chunk out of the bestseller pie. No one can argue that sex doesn’t sell.

But what fraction should sex occupy in fiction? Given that writers now have so much freedom in writing about sex, it doesn’t hurt to stop and re-evaluate what the writer wants to achieve. How necessary is it, and is it just thrown in for the purpose of titillating? Whether the intercourse is heterosexual, homosexual, or otherwise, it must be written to identify the relationship between or among characters, and whatever changes might ensue as the story progresses. Exchange of body fluids and how two human bodies slither against each other may arouse interest in reading, but if it does not open an opportunity for self-realization in the characters, the plot becomes tenuous.

If a man and a woman met in a bar and decided to make out at her apartment for the first time, the writer must use the sex scene to establish a new relationship and reveal aspects of how the man and woman view their make-out session. It must reveal concealed sentiments rather than just showing a juxtaposition of genitalia. 

Example (their first time together): As soon as she locked the door, she grabbed him by the face and kissed him ravenously, the smell of alcohol in his breath arousing her. She pinned him to the bed, ripped open his shirt and slapped him. “Ouch! Take it easy,” he said. She grinned and said, “I like it rough.” From the drawer of her bedside table, she pulled out a pair of handcuffs.

This ephemeral relationship reveals more information about the characters. We do not project our true selves when meeting people for the first time. The sex scene has helped reveal character and their one-night relationship may or may continue depending if the man is a masochist or not. Whether the writer depicts sex as rough or romantic, it must bring about transition and help define character.

Example (long-term relationship): Lexie spread her legs, anticipating his move. As he positioned himself on top of her, he asked, “What are you gonna be this time-- a nurse? A secretary? A lady cop?” She shook her head and said, “Please, no more role-playing. You’re hurting me!” He looked at her with consternation. “It doesn’t matter. Today, you’re a homemaker.” He ravished her while inflicting bite marks on her perky breasts. Alexine cried in silence. Her mother was right: It was time to leave him.

Smut writing is an entirely different thing where sex is thrown in just to trigger arousal. Similarly, lust and romance operate on different levels. Either way, both must be written to establish the relationship between the characters and help readers gain more insight as the story unfolds.