I’ve lurked since August 1. I haven’t added anything yet, mainly because I read the book in January.
Oops: I see @Mary13 just clarified the following for me.
I knew Duchess couldn’t read or swim. Hints were dropped in early. Billy read something to him early in the book, maybe more than once. I forget the exact excuses but something along the lines of something in his eye or read it to me while I do whatever. Duchess refused to swim back when the boys slipped out to see a movie (or something like that). Again Duchess had an excuse.
I like the book, but more than that I like how Towles writes. A Gentleman in Moscow and The Lincoln Highway: did the same author even write them? I mean that in a good way. Towles doesn’t repeat himself.
Re Duchess: I think of him as the catalytic character.
A catalyst character, also called the impact character, is a supporting character who in some way does something to annoy or urge the main character to take action and start the show. He is also the Jungian archetype called the Magician. Although Jung may see him as a visionary, this character is usually the shaker-upper of the status quo. A catalyst in a work of fiction can surely be an event or another force other than a character, but in this editorial, we shall concentrate on when the catalyst is a character.
The catalyst character can be likened to the spark that lights the fuse. It is, therefore, a very good idea to create him before plotting the story extensively. One thing to keep in mind is: the catalyst character’s action hints at the psychological foundations of the story. This is because the true natures of the various characters are glimpsed during the catalyst’s action. On the other hand, while the other characters may change by the end of the story, the character arc of the catalyst character usually stays flat.
To choose a catalyst character we need to keep in mind these facts:
The catalyst character connects to the other characters in some way. He may be a friend or a rival. He could also be a coach or a father figure. He could also turn out as an antagonist or the ally to the antagonist.
The catalyst character has to do with or relates to the inner conflict of the protagonist or the plot. For example, Dickens chose the ghosts to urge Scrooge out of being miserly and self-serving.
The catalyst does not change himself but urges the change in the other characters or the plot. In addition, he should be written out of the story once his role is finished.
Drama: Creating the Catalyst Character - Writing.Com
I figured Duchess as a picaresque hero:
… a picaresque hero is in no way a virtuous person. He often emerges as a low character who resides in an infamous social structure. No hamartia is there to mold his fate. Wits are the ultimate tool that forces him to design his destiny. He is the architect of his future, and it is up to him to decide whether he should fit for a job or whether he should hold on to a job.
The most significant contrast between a tragic and a picaresque hero is that the latter never enjoys any improvement in his character. It means a rogue always remains a rogue. Even if he is put in a better social environment, he can’t afford any changes in his rogue characters. The primary thing is a tragic protagonist always tries to maintain a positive development in his thoughts. But a change of heart is a rare or almost impossible trait for a picaresque hero.
Moreover, because of the wit, a picaro often never reaches the point of criminality, although his character obtains immoral, dishonest behavior. And, most surprisingly this characteristic helps him to emerge as the sympathetic outsider. Unlike a tragic hero, he is more realistic with no exaggeration in his character. That means he lives in a society that never opens up any scope for imaginative or false rules.
https://makewordslouder.com/define-a-contrast-between-a-tragic-and-a-picaresque-hero
And off the Duchess topic for a moment: @Mary13 hit the nail on the head with her thoughts on why Sally appeared in the story at all. She bothered me till Mary wondered if Towles needed a female presence no matter how ill-fitted into the tale.