Status Updates From The Outlandish Companion: I...

Drums of Autumn-now this one is interesting but less easily defined. It’s shaped like a curving rose stem, with a budding offshoot (Roger and Brianna’s story) and a lot of thorns, ending in a big showy whorl of flower, where all the petals of the plot come together.

Claire is telling her story backward (to Roger and Brianna), and Roger’s story is set in the present moment and provides a turning point to switch between Jamie and Claire’s.
(Yes they get more complicated as we go on. Anybody’s life gets more complex as they get older.)

Now, Voyager is shaped like a braided horsetail. It has a triple narrative through the first third of the book, with Jamie’s, Claire’s, and Roger’s voices taking turns, then falls into a simple linear narrative in Claire’s voice through the second two-thirds of the story. I quite liked the structure through the early part: Jamie is telling his story forward as it happens,… continue

Dragonfly in Amber is dumbbell-shaped.
You have a small arc of framing story at beginning and end (these would be the nuts or fasteners that hold the weights on), then then two larger arcs, one dealing with the political intrigue in France, the other the actual battles and events of the Rising (these are the weights); these two main arcs are connected by a relatively level stretch of peace at Lallybroch.

Outlander, for example, has three slightly overlapping triangles. There are three emotional climaxes in the story (these occurring at the spice of the triangles; when Claire makes her choice at the stones, when she rescues Jamie from Wentworh, and when she saves his soul at the abbey.

PART SIX: WHERE TITLES COME FROM
All my books have an internal geometric share that emerges in the course of the work, and once I’ve seen it, the writing goes much faster.
…
These internal shapes are normally invisible to the reader-who isn’t looking for them in the first place-but if pointed out, the reader can certainly see them.