If you're asking about the technical side of things, I mainly use Blender, I do some texturing there too, and Clip Studio Paint for the rest of the textures. Those are my main programs and not the only one.
I don't know how to draw, so I almost never have concept art. I just model from my head, which doesn't always work out, so most of the time it's what I call “3D sketching'"until something works out.
I usually have a concept for the character’s personality, storyline, etc., and I build the character based on that. A lot of my characters don’t turn out well and don’t make it into the game, but there are also a few that are pretty close to making it into the game.
If you're asking about the concept and idea behind the character itself,I’ve never actually been short on ideas, I don't really have any specific inspirations. Sometimes throughout the day, I'll come up with a few new characters in my head, complete with a full backstory, personality, and so on, and I try to bring to life the ones that really captivate me.
As I mentioned in a recent reply here, I have a few hundred of these fully developed characters (talking about the plot, appearance, personality, etc.), and I'm sure they'd each attract their own fans, so there's plenty to choose from.
The elf wasn’t planned for the game this early on, but since I really liked her story, its various endings, and other elements which, admittedly, aren’t in the game yet but will be, Eli just kind of snuck her way into the mix of other characters. So with me, you can’t be sure what will make it into the game or in what order, the only thing you can be sure of is that I’m working on the game.