Mathematical plot devices.

Technically this should be called a “love angle,” and “love triangle” should be reserved for situations where the two suitors are also in love with each other.

Been a while since I’ve seen it, but I’m pretty sure this is what Lion in Winter was about. (Note that the backstabbing can be figurative or, if you’re working in a genre with a high level of violence, literal.)

Not always a fun story. Sometimes too real. (Also, there’s no law that says each character’s in-degree must be the same as their out-degree. But it’s just good storytelling.)

My friend Becky Dinerstein Knight wrote a juicy book called Hex that was, to oversimplify its geometry, a more scandalous version of this.

Watch out for characters falling in love across enemy lines. This may make for good theater, but it totally ruins the bipartite structure.

There’s just no rational way to factor that guy.

Freaky Friday-style plotlines often overlook a crucial source of horror: all of those people who wake up, mortified and aggrieved, to discover that they’re still in the same stupid body.

Pro tip: if you’re writing this screenplay, you’re going to need a bigger whiteboard.