My characters are the driving force behind my stories. I would say their personalities definitely influence the plot, probably similar to choose-your-path video games with the good and bad and in-between endings. If I modified their personalities enough, they wouldn’t participate in the plot, or there simply would be no plot. They definitely are not interchangeable between stories . . .
But I also want to point out, I spend a lot of time just thinking about the characters: what they would do in random situations, how things they have done affect other characters, how their pasts affect them, how they would react if they knew their futures (for some of them, they’d definitely do things differently), etc. This is not done on paper at all. Just in my head, daydreaming and entertaining myself so I’m not bored in real life. Listening to music really helps enhance this.
Basically, I feel like in order to properly create a character, someone should be able to ask you any question about the character in question and you be able to give an at least semi-coherent answer.
That said, my characters get short leashes. I’m mostly deciding things for them because I know them well enough that I know I can do that. I’ve already daydreamed, tried it out in my head. But they do have leashes. And sometimes they seem to tempt me to change my decisions. If that happens, I feel like that may signal a plot hole I need to sew up (because if I see it, others will, too), or I may need to actually listen to them and lean more into whatever they seem to be suggesting.
That does sound a lot like what I do, just better put. Main difference I'm seeing is I give mine some pretty damn long leashes, occasionally to my and the story's detriment, but I feel the potential reward is worth the risk. I like to follow them down different potential story paths, as a process of elimination and place to pick up stray ideas. It's something to do while waiting for the Muse to crack me over the head with the good stuff.
I’ve never experienced the ‘ character won’t do what they are told’ thing because characters can only do what we make them do
In most cases this is short hand for the author subconsciously feeling that the actions aren’t right . That also doesn’t happen to me often but if it does I may go back and change things
It can also be a short hand for pantsing the plot and creating characters without a clear idea of what you are going to have them do before you start… I do that all the time.
They certainly will do as instructed, if one insists. At points in the process that becomes necessary. It's all just suspension of disbelief, metaphor and framing device. Helps me connect to what I'm working on and keep my interest going if I pretend I'm watching something unfold rather than thinking it up. If I sit down and actively try to think about it I'm very prone to tripping over my own mental feet. I've tried both ways, and both have their uses. Logical thought is something I bring on board more and more in later revisions, but the first few drafts are for figuring out what I'm even supposed to be thinking about. So yeah, very much a discovery writer and far more interested in people and worlds than plots, so I guess it's natural I work the way I do. It's not very efficient, but generally produces higher quality stuff than other methods I've tried. Suspect I've erred a tiny bit too much on that side of things, I'm still trying to fine-tune it.