I’d asked in the spiky book club server what topics they’d like to see me touch on in posts, and the first response was to ask about fleshing out supporting characters. Which is a good point. No one wants to wander into a book and see a bunch of cardboard cutouts propping up the joint.
The quick and easy answer to filling out a supporting cast is to remember that each of them is a person (whether human, cat-dragon hybrid, or silicone based lifeform) with motivations and reactions. They will act, or react, based on what is being done in the story. You have to give them logical motions or the reader is going to wonder if they are just part of the scenery – hence the reviews complaining about wooden supports. Why logical? Well, real life is full of mysteries and conundrums, and while sometimes you might be able to figure out the underlying rationale of the people around you, mostly you won’t. In fiction, though, you should give some reassuring clarity to the readers.
The counterpoint to giving them motivation is that it needs to be a weaker, less fully-defined motive than your main character. If it’s stronger, you begin to invert your main character into a supporting character. The more formed they are the more likely they are to take on a life of their own and start taking over, in my experience. This is easier in a short story, where you don’t want a large cast of characters, and in a series, where you can promise that character a spin-off all their own, if they will queue patiently over there while you give your MC the conflict plot arc of their lives, dropping them off into a resolved state before you come back to the impatiently toe-tapping side characters to give them a thrill as well.
One side benefit of fully-formed characters is that your book will fill out, too. From the bare bones of the plot, you suddenly have a population in it, running around doing things. Those things might be tripping up the protagonist while he’s trying to get to his end goal and resolution. They might also be helping him get where he’s going, especially if he’s taking on a task too large for one person to handle all his ownself.
To fill out a character, you don’t have to go into minute detail of physical description. In fact, you really should refrain from that. For a side character, a thumbnail sketch is sufficient. However, by giving the reader some idea of the people surrounding the MC, you are also limning that character in reflected light. We are who we hang out with, in fiction as in life. Showing the motivation through reactions described in action in the story will give a support, or a contrast, to the main character. If he’s buddied up with a group of thugs, you don’t expect him to be pure as the driven snow. More like where the dogs have been walked. If the MC is surrounded by a group of elite fighting warriors who treat him with respect (in their own way, which may look like abusive teasing) then you don’t expect him to be a yellow-bellied coward dealt the white feather.
Here’s a good place to use the primary questions: who, what, why, how, and where. Who is the character, and I don’t mean who she says she is, but the deep underlying motives that drive her. What is she doing in the story? Why is she doing that? How will she accomplish her goals – not the MC’s, but the supporting character’s – as the story progresses, and yes, that might be her going along with her friend to help her friend the MC win through. Where did she come from and where is she going in the scope of the story, or beyond in a series where she has the opportunity to audition for her own leading role in a later book.
When it comes to supporting characters, the further out from the central characters they get, the more they can be simply Ionic, Doric… oh, fine, you know what I mean! They can just hold up the place, rather than needing to have things like arms and legs, much less clearly defined personalities. However, it’s not difficult to ask the character a few questions, when they have a speaking role, and then as the author you can put a little of that on the page, and voila! They will spring to life. If you’re like me, then you’ll spend more time beating them off with a stick to keep them in their place in the story!
(header and three women at the well are by Cedar Sanderson, rendered using MidJourney)
Mad Genius Club 
I find the secondary characters (and sometimes walk-ons) are also useful for providing POVs about the main character (not just about off-screen events). They can describe or wonder about the main character’s appearance/actions/reactions in ways where we want the reader to puzzle about it, too, when we’re not ready to lessen the suspense and give the readers the main character’s POV about something.
I find it much more absorbing for a reader to do that via a secondary character than via authorial voice (which I hate), and as a bonus you get to flesh out the secondary character’s personality as well.
In a long series, though, you have to give thought to the more important secondary characters’ life stories and fates, as you say. I’m not a big fan of spinoffs (looking at you Nathan Lowell), but I don’t have any issues with the secondary characters living their lives along with the main one’s, as secondary punctuations of events. A secondary character’s wedding can provide an important spying opportunity for the main character, after all.
Readers vary… I don’t usually kill a secondary character just to make the primary character react, but I have killed secondary characters. Every time I do that, I hear about it from First Reader. In one book, a tragically damaged powerful teenage girl was (necessarily) killed by the main character female wizard (instead of being somehow rehabilitated as an apprentice), and ever after I’ve been hearing about my propensity to “kill Robin”.
Some people (raises hand) love big sprawling interconnected series. Others (looks over at husband) loathe them. I think it’s yet another case of knowing your audience, or better yet, knowing what you like to write and finding the audience who also likes that.
My problem with big sprawling series is that what I really want is my (entry point) main character back. I didn’t fall in love with the world-building, I fell in love with the characters. So when I read the spinoffs, I’m always looking for the momentary glimpse (if any) of the original main character or his life, and always being disappointed. I’ve never been fond of generation-spanning historical novels either. My interest isn’t retained by dynasties or worlds — I want to know more about people I know.
The Liaden material has gotten large enough that there are now (to me) several main characters, but that’s a rare exception for my psychology (and even so I waste far too much time trying to remember how they are all related/associated). I wish Nathan Lowell, fond as I am of him, would concentrate on more existing-character stories rather than putzing around with peripherals, but readers can’t (and shouldn’t) try to tell writers what to do. So this is just one reader’s perspective… 🙂
I’m with you as a reader, and kind of on the other side as a writer, because I tend to get bored with my main characters after a while. Granted, the replacement main characters sometimes end up being fun-house mirror versions of the previous ones, but they’re different enough that I can’t pass them off as further adventures of the same people.
I felt that way for my first two series which weren’t planned for a long run and came to a natural conclusion after 4 books (though I left enough wiggle room that I could extend them if it seemed like a good idea).
My current series is different — the MC is building an Industrial Revolution of magic, and I spent my career in tech businesses — I can screw around with this sort of theme indefinitely, and thus so can my MC, even as his life matures. That’s one reason I’ve spent so much time setting it up and holding the first releases until all my ducks are in a row after book 3.
That sounds like a lot of fun honestly, good luck to you and MC 🙂
Rushalentar thanks you. 🙂
Well, you could do an Agatha Christie, who created a character (Ariadne Oliver, a mystery writer) in her Poirot series to let her complain about Poirot (Oliver complains about her main series character, a Finnish detective, just like Christie at times regretted creating Poirot)
Hah, yes, was watching/reading some of those lately.
The joy of working with romance tropes as well as mil-SF ones: romance readers expect a series to be one book (and HEA) for each character in a group. Which means when Twitch showed up on the balcony, they rolled with it as “perfectly normal”, while I was still staring in horror and going “What are you doing here? Is this a… a… a sequel?”
And then when he showed up outside Jenna’s dressing room, and maneuvered AJ into tightening a corset, well, my romance readers squeed and told me they’d been expecting this. I hadn’t, but they had.
… And then started putting in requests for who they thought should be next.
I read some Romance, so I recognize the 4-books-to-marry-4-sisters sort of thing, but it always seems forced to me (Nora Roberts can pull it off sometimes – e.g., The Inn Boonsboro, but that one has all the relevant players on stage from the first book).
I like the great-big-family/one romance (maybe hint of another) 1-book versions better. The big-family aspect deepens the mise-en-scene, and 1 romance within it is all you really need to complete the story.
Of course, it’s notorious how (professionally) idiosyncratic Romances and their readers are — specific keys to fit specific psychological locks. SFF is much broader in its “a few sizes fit many” approach.
Oh, I wouldn’t say romance as a genre is idiosyncratic and SF/F isn’t – after all, it’s a much broader genre. Given it’s making billions of dollars a year to SF&F’s tens of millions, most of its many sizes are definitely fitting many, many more readers.
One of the biggest problems to me is that if you stick with the same main character(s), then the nature of the story almost inevitably has to change. Outside of a few genres like mystery, where you can (not must, but can) be as episodic as a sitcom without seriously changing the main characters, the story makes the characters grow and change.
Which then means the next book must address that growth, and the one after that, and so on. The plucky midshipman becomes the captain, and then the admiral – and the kind of story you can write with the plucky midshipman is completely different than the kind of story you can write with the admiral.
Even if your plot is “the monster comes to town”, the main characters or party will get power creep, and corresponding scope creep… and sooner or later, you get Fate Of World instead of plucky adventurers having fun.
…Or you get Latest Installment Of Power Politics with a small crabbed fight scene, or a solid short story padded out to novel length by Who’s She Sleeping With This Week (and all the ensuing drama).
So changing the character allows you to keep the story size and scope you want, while staying in the world you like, and seeing the others in the distance.
There are all sorts of adventures where the main character does not change.
A good tactic for those is to have important secondary characters who change and grow — and leave.
I have good luck with assigning character traits. Make your characters like the Olympians — this one picks fights, this one drinks too much, this one does crafts. Oddly enough they may demand larger parts and develop motives.
Which reminded me that I should take notes on the wonderful varieties of magic a knight can have in my world, so I don’t stick to the same ones in the later books, and also because they’re personality powers. . . .
I was considerably more wild and woolly than I had thought.
I seem to recall a half-joking comment about the Weber-verse (Honorverse) that when a very minor character got a full-page description, the reader knew said character wasn’t going to live to the end of the book. It’s been so long since I’ve read in Weber’s world that I don’t know if it still applies. Granted, he writes books long enough that he can get away with lots of description.
I seem to focus on one characteristic that’s memorable “industrial Goth wearing an Imagine Dragons concert tour shirt” or Lady Fatima the actuary/drag-club owner. Or the partial antagonist in the new WIP, who wants the MC to be trained as a healer, but only so the MC can take care of Master Ari’s livestock and family, and who will try to legally force the young man to stay on the farm. Master Ari has very good reasons for wanting a beast healer who doesn’t need to be paid for his services, or paid only in room, board, and clothes. The MC has other ideas, even if he’s not certain what those ideas are.
Primary characters get a lot of details, because they need those details. Hell, I’ve got five, six page biographies written for each of my main cast in Solist At Large and the sequels, nearly a hundred pages of details.
Secondary cast is a bit looser…but there’s some interesting details there. I also tend to…file serial numbers off when I can to get the right secondary character and Hilarity Ensues when that happens.
Thank you, I found this helpful 🙂
One thing about naval fiction (and military fiction in general) is that you have a pretty much built-in set of secondary characters.
If the MC is a junior officer, you will have at least one officer senior to him / her, along with fellow juniors and usually a relatively senior NCO acting as a mentor. As the MC grows in rank & experience, the list will expand to include other peer officers and more senior superiors.
When the MC gets their first command (a very common mil-fic trope) there can be more characters to play with (subordinate officers, senior enlisted, etc.) In naval fiction particularly, the ship can become a character in and of itself, the classic example being USS Enterprise from Star Trek.
Finally, when the MC is a senior officer, they may start encountering the political leaders of their nation / kingdom / empire, and possibly those of other nations.
Then, of course, there are the bad guys…
This was an absolutely brutal part of the space opera I’m working on (final revisions) right now. I had an enemy Admiral as a somewhat important POV character, the captains of his strike force as minor character who were somewhat relevant to the plot (mostly with regards to his decision to defy orders), plus the main characters from the previous book, plus another Admiral, plus the captain of Other Admiral’s flagship. It was a lot of people to juggle and give names to; at one point in the revisions process one of the captains in the strike force had two different names.
The classic example being David Weber’s Honorverse, as well as his series inspiration.
Yep, and like in the Honorverse, you can reach the point where your MC becomes too senior to be out there having first-hand adventures. This leads to secondary or even tertiary characters stepping up into a quasi-main character position.
I did this semi-deliberately with Karl von Stahlberg, fast-tracking him into a senior command role because it was necessary for the overall plot of the current story arc. But not too senior. He still gets shot at, but the guns are somewhat larger now, both literally and figuratively. 😁
And his peers are men like Chester Nimitz and Sir James Somerville, which brings its own kind of fun.
LOL, yeah, that is always ‘fun’… But after 20+ years, I have PLENTY of good/bad examples to draw on.