A friend of mine from Hollywood -- after looking at a query tied to a book series I'm working on with my wife -- suggested I watch Castle. She recommended that I write a TV pilot because our work has the potential for the kind of sustained sexual tension that's found in that popular TV series.
Now, while ideas may be the currency of science fiction and puzzles may be the currency of mysteries, sexual tension is the El Dorado of romance. What could I learn by watching this series? It turns out, the answer was pretty obvious. There is a power struggle between the two romantic leads. Both have things the other wants and both have vulnerabilities. And, most importantly, if either were to surrender to romance, the exposure in terms of prestige, employment, and self-identity would be too much. The stakes, without deep and abiding trust between the two parties, are just too high.
Spoiler alert: let me get specific about Castle. With his writing career at a crossroads, and writers block threatening, Rick Castle needs the inspiration of real crimes and enough participation in and appreciation of the real process of solving crimes to create the stories in his next series—featuring a stand-in for Detective Kate Beckett.
Detective Beckett benefits (somewhat) from Rick Castle's wealth and connections. She also is under orders by her boss (and apparently up the line) to show Castle consideration.
When each enters fully into the other person's world, there is potential for humiliation. Detective Beckett can be demeaned in front of her peers by Castle's remarks and actions. And we see that happen, so the threat is not idle. Detective Beckett makes a point to going to a book signing where she's able to show her power to knock Castle off track in his world. (And, with such a powerful hero, the writers are very clever to include his family members who are able to ground him and expose his weaknesses.)
So, both characters need each other and both characters are vulnerable in an interlocking relationship that is not optional and ongoing. It is this relationship that both ensures interactions over a long period of time, with interesting variations, and makes full commitment to romance (and sex) problematic. Any time they edge up to the line between work and love, they get reminded of how badly things could go. They feel pain.
Of course, this sort of a guide to sexual tension has uses beyond romance. Most obviously, a buddy movie has the same elements with friendship replacing love. An argument could be made as well for stories where the bond between an individual and the group or between competitors or between a hero and the villain is central to the narrative.
For me, an immediate outcome of this analysis was an understanding that both characters throughout need many opportunities to take action that matters. Their agency must be demonstrated. In addition, the stakes need to be present and clear in almost every interaction.
So, I've taken my lesson, and I hope you'll take the opportunity to watch a story that has sexual tension (or at least, tension around the friendship), and see what it has to tell you about your own work.