The structure of this snippet is simple, but there are some interesting details that help create the feeling of suspended animation.
Background action: This could be your secondary character or a new tertiary character for this scene, or both, it’s up to you. It’s just background action.
(Notice the verb tense. Tim Winton writes “Mr and Mr Mann are arguing…” not “Mr and Mr Mann argue…” This is called the present continuous tense, and you might notice it enhances that floaty, timeless feeling.)
Narrator action: This could be anything, but again you can consider using the present continuous tense (I am doing).
Callback to earlier metaphor: One of the best ways to end a story is to reincorporate a significant detail from earlier in the story. We set up a strong metaphor in Lesson 3. Bring it back here and find a way to make it fit into the scene. If you do this right, it will create a sense of closure and finality.
It’s interesting to notice that you can end so well on an image. You don’t have to resolve everything in your plot, you don’t have to answer every question. Ending on the right detail can feel completely satisfying, so long as the detail has been given weight and meaning earlier in the story.
FAQ: What's the deal with Mr and Mr Mann?
It looks like a typo, but there are two Mann brothers in the scene, and Ort only knows them both as Mr Mann.