When I think of the crowdedness of The Sundial, and the overstocking of characters I wonder if it is a sign that Shirley Jackson did not know what to do to feed the plot so she threw more people in to keep the meat-grinder going with introductions and minor permutations, but very minor; Arabella, Julia, Gloria and Maryjane could have been merged somehow I ween or reckon, a nudge and one could have taken on the plot-functions of another, the other could have been dismissed, the initial one could have been written to explain the new behaviour. What if Julia had been eliminated and Maryjane had run away instead? Is Captain Scarabombardon essential? Why did she bring in this mob, why didn't she stop where she began; she began with a small group of well-delineated people in a closed space, a house, the setting for a closet drama, tensions there, etc, but then she draws more people to the house, a woman and her daughters, then another man, then introduces the reader to the people who live in the village outside the grounds of this mansion, and then diverts away into the story of a murder among the townspeople decades ago; everyone who was involved is dead, including the acquitted woman who might have been the murderer and this, although the readers at the time didn't know it and possibly not even Shirley Jackson herself when she inserted the murder-story in the book, was going to be the seed of We Have Always Lived in the Castle, published four later in 1962, with two women living in the house instead of one, sisters, one of them accused of the murder, and the townspeople whispering about them as they do in the story Jackson has inserted into The Sundial.
So one book has fed on the other; the Sundial has this first draft in it and so many things about it feel like the first sketch of a story, the jotted flattened characters, the dialogue of the arch young man that could have been lifted from a stock character in a movie, say one of those 1940s comedies with quick to and fro. But then the way he keeps tapping or scratching on his love's defenses without any apparent hope of actually getting in, like a dog with its door nailed shut, this habit that acts like a nail, nailing him into my memory, poor arch young man (whose name is Essex, the sad bastard), stuck with his love and his stereotypical lines, until the stereotypical lines feel like the well-worn social thing he resorts to because appeals for affection do not work.* A sign, not of lack of imagination in the author but of deprivation in the character. So my imagination works on him, I concoct a character for the man, and I had a similar reaction when I had to read L.P. Hartley's The Go-Between in Year 12 English and over the course of six months became fixated on the extremely minor character Denys, the lead woman's brother, who does virtually nothing except offer to play tennis and I resented the young lead woman, the protagonist-boy, and the annoying lover, who were taking valuable page-room away from forgotten Denys and depriving him of any chance to display the personality I had invented for him in private.
I disliked the boy-protagonist even more after I had seen the movie by Joseph Losey, whose scriptwriter Harold Pinter (though I like his Proust adaptation) had parenthesised the plot with future scenes in which the adulted boy-protagonist visits the now-elderly lead woman and engages with her sadly because the thing he saw in that garden shed thanks to her scarred him for life, her betrayal made him frigid forever, moped this mournful stoic as I sat there throwing objects mentally at the screen and invisibly shouting unsympathetic mottoes I had learned from my time in the world, eg, "Build a bridge," though my feelings I believe were more complicated than those phrases suggested, a mixture of my psychological depths which I evidently preferred not to recognise, signalling this absence of recognition with brief abuses.
*If you have read the book and you want to argue that Essex is only being diplomatic not genuinely affectionate ("Essex is primarily a politician," the older woman says) then I agree with you to and I can see all the evidence for it.