Writing sex is hard, as I said in a previous post, because the palette of actions is so limited. But writing attraction (the emotions and behaviours that precede sex) is easy because you have a wide range of choices, most of which allow you to fill out the reader’s sense of the character and push the plot forward.

• Naïve or unreliable responses. Your character may be unaware of what is happening to her, though you can make the reader aware. Other characters may also clearly see the attraction, including jealous partners.
• Fighting the attraction. Related to the first, your character may fight the sensations and thoughts that come with her attraction. She may deny or be disgusted by the attraction (attraction needn’t be experienced by a character as a positive thing).
• Dangerous things threaten. Again, related to the point before, there may be strong plot consequences of the attraction that lead your characters to fight against it
• Fast or slow. The attraction may be something that builds slowly during the course of the story or it may become a tension that threatens to  boil over.

So how do you write it?

Attraction manifests both physically and mentally:

• Physical sensations may include a heightened awareness of the other person, including eyes lingering on them (especially on mouth and lips, as well as breasts and pecs, buttocks and bulges) and responses to their scent. There will also be a strong reaction to any physical contact. There will be wetness and erections. And, of course, the old standby of romantic fiction, the palpitating heart
• Mental and emotional responses include day-dreaming about the other person, a sense of being intensely in the present when with the desired one (time stops), and bringing up the other person in conversation without any appropriate reason (obsession). Your characters may feel a sense of having always known each other. They may feel a sense of being perfectly matched. In the fighting the attraction scenario, there may also be anxiety or fear.

Here are some tricks:

• Make the attraction immediate and powerful when the characters first meet.
• Tease your reader. Vary the tension
• Make the chemistry stronger each time the characters are together.
• Use descriptive details (such as awareness of the texture of things touched) that show the character’s heightened awareness
• You can have one or both characters deny and fight the attraction, especially where there are dangerous consequences.
• The old romantic trope of something tearing the characters apart before consummation always works well.
• Ensure your characters behave differently with each other than they do with other people