After finishing an extremely rough draft for my Cinderella retelling, I realized that I write in layers.
The first layer is the biggest layer. It's the main plot. Each additional layer is a subplot. And I've discovered that I cannot really think too much about the subplots until I've nailed the plot.
And, I don't ever seem to come up with an ending the first time around. So this time, I did what I did in Starcaster on purpose, and in The Sevenfold Spell by accident. I left the ending unfinished. (With The Sevenfold Spell, I thought I had an ending, but I discovered I did not.)
But more on layers. As I was writing, I knew there would be an uneven romance between commoner Yvette and nobleman Pierre. But I didn't know exactly how it would work out. I also knew that Pierre's sister would be a problem for Yvette, and I knew how she would be in the overarching plot (she's after revenge), but I didn't know how I was going to make it personal for Yvette. I'm a bit closer now--and it will involve Pierre.
I also have this whole jealousy subplot with the stepsisters, and I realized that overcoming jealousy would be the whole theme behind the novella.
So there's four layers - the main plot, the romantic subplot, the revenge subplot, the stepsister subplot. Each plot/subplot equals one major character, so we have Yvette, Pierre, Esmerele and Agnes.
Since the main plot--the extremely sketchy main plot--worked out to 13,000 words, I think that will fill up a 20,000 word novella quite nicely.
In other news, my proposed series title for my fairy tale retellings is now official! The series will be called Accidental Enchantments. I'm thrilled!