In the story I'm writing there are a lot of characters who have roles in contributing to the plot, but are out of the main focus of the story. For example, the MC in my story is a soldier and his commander weave's in and out of the story at various times. I need the readers to easily recognise him when referenced but I don't want to spend time on his character and away from the plot. Any help or advice is appreciated.
As much as I can in the limited space they have. That's how much depth. Make them real, give them more than they neeed; but then show as much as much of that as fits, hinting at the rest. Or that's my thoughts at least.
Every character should have just as much depth as any, the difference is the space you have it to show it in. Main characters have the entire novel, secondary characters have key scenes, and anyone else just the one moment they show up in. It doesn't have to be a pool of depth, just enough to not make them bland non-talking NPCs.
Depends. Some characters have a soul purpose for showing up - kinda like the barber in Lolita who is talking to Humbert about his son who doesn't realize that the son is dead. And this character forshadows the whole story - Humbert becomes him, locked into discussing people who have died. Or they have their own quirks which just add to the flavor of the story. In my WIP there is a handful of cons that appear and reappear along with the main characters one for example is the 'librarian' who tears books in half and sells the front for cheaper and ups the price for the last section. It all depends on the tone you're going for.
I think a great deal of this question begins and ends with the goals you have for the character. If your MC repeatedly walks into an office and passes a secretary on his way to meet his boss you probably don't need to give much personality to the secretary if the real focus of the scene is always the boss. If you have a character that is going to have an affect on the MC then maybe you need to fill it in some. For these little side characters I only follow one absolute rule and a one minor rule. The major rule (for me anyway) is that I never give two characters similar names. I've read too many books where this has caused unnecessary confusion. Especially important for little characters where the reader doesn't have enough information to differentiate between them. (Please say the names out-loud. If you want to publish your story keep in mind that it may end up in an audio format.) Of lesser importance, I try to give the little characters one identifying characteristic. Maybe they limp, or speak in a very different manner than other people. I had one character that only showed up at the most inappropriate times so the MC was always saying things like "Of course he would show up now." reminding people who the character was. There's my nickle advice.
I try to give them a little one paragraph backstory in my notes. So say I had this Commander character, maybe I note he has a rocky marriage, that he has cheated on his wife with several assistants and she knows about some of them. Maybe he plays poker too much, loves college football, etc, etc. And use those little facts if I thought it was warranted. It helps me get a feel for how the character would act/react. If a character like that were weaving in and out of the story, maybe he could smoke cigars. The scent would precede him and hang after he left. Or he's always wearing an LSU hat against dress code. I think I would go with a little flavor like that, something that readers would remember, the other characters would remark upon, something that would etch itself into the scenes.
It depends on the character. If the tertiary character has to make a decision to drive the plot, that is a very questionable and complex decision than I will have to spend time developing that character to make that decision. If the character is very simple, then he/she may not need much time spent on development, if that makes sense.
I tend to give EVERY character in my story backstory even if it isn't going to be in the book. It just helps me
I do too! even if I don't mention it in the story I know exactly what makes each of them tic, But thats kind of my problem. I know all these side characters backstories and why they make the decisions they do, and what led them to play whatever small role it is they have in the plot. I know these things, but the readers don't. and most of it is unimportant (to the overall story). So Im just wondering how other people treat their one-off or rarely seen characters.