Duology vs. trilogy - a battle to the death

Writing trilogies is rather straightforward.

That's not to say it's easy, because writing generally isn't. As a rule, writing is difficult. But structurally, trilogies make sense. They have beginning books, middle books, and end books. Of course, generally those books must each have a beginning, middle, and end themselves.

But duologies are a bit different, what with having two books. Each book gets a beginning, middle, and end, but what about the series arc?

An illustration with glitter pens. So sorry for my handwriting.

See how with trilogies, the middle of the middle book is the middle of the series, too? But with duologies, there is no middle book. So where does the middle go???

My friends, it falls in between the books. As if middles aren't tricky enough, the middle of a duology plants its weird little flag right between the books. (This makes a great place for cliffhangers, hahahahaha, sorry readers I love you.)

Let's look at what kind of things usually happen in middles. (Conveniently, I have written a blog post about middles before.)

My feeling is that middles should always make things worse, either by building on the already established conflict, or complicating it. In the middle of the middle book, that's pretty straightforward. But at the climax of the first book? In the beginning of the second book? How do you also make that The Middle?

Carefully, gentle reader. Carefully.

So, in the climax of a duology's first book, you can middle it up by changing the game to make things worse for the characters. Send in a new character. Reveal that something they thought they knew to be true . . . is actually false. This is the time to do the big turn -- and make it really dramatic because this is the climax of a book, too.

In the beginning of the second book, it helps to try to pull back and see the longer arc of the story. What would happen here naturally? It really helped me to stop thinking of it as a beginning -- at least for the first draft -- and instead think of it as more of the middle. Like, if I'd finished the end of the first book and just kept on going like there was no break. Then, when I had my plot and character and everything down, I looked back to see where I needed reminders about the previous book, and how I could make this middle also a beginning.

So, you may be asking where is the battle to the death between trilogies and duologies. There isn't one. That was mostly click bait. Trilogies and duologies are both awesome.

What are your thoughts about duologies and trilogies? Do you have any tips for wrapping your head around the long-arc structures?