@Owlor It's a great writing principle! But I'd say that what an author really does is create a good *illusion* that this is true of their characters? I mean that in kind of an esoteric and really specific sense, though, so let me see if I can clarify a little...

To give an extreme example, you know for years there were debates about what state Springfield from the Simpsons is really in? And people would rush in seriously insisting they could prove what state it was, because there were only 50 choices, and there HAD to be a real answer, right?

Well, of course not. Because Simpsons is a very, very low continuity show, where the creators not only don't always care about internal consistency, sometimes they go out of their way to make it impossible.

And yet fans will often try to apply this same kind of logic to series that don't even take place in reality. They'll try to figure out things like, say, the exact genetics of centaur hybrids in Centaurworld or something.

And those things are fun to play with, but when people take them as Objectively Real with only one solution, it's... kinda silly. And I feel like one of the fallacies fan theories like these commit is assuming that a literary reality has to work like a fictional one.

Like, to give another extremely silly example, "If Cap'n Crunch is a captain now, doesn't that mean that at one point he was an Ensign Crunch and had to work his way up the ranks? Yet there was never an Ensign Crunch cereal. So CLEARLY what happened is that he started out as an officer. But this practice was abolished by the British Navy in 1852*, so the only explanation left is bribery or nepotism. Is our Dear Cap'n CORRUPT?! Is he the true villain of the Quaker Oats Multiverse?"

It's that kind of stuff I'm talking about. There's a little bit of "because the author said so" in even the most realistic of stories, because that's just inherent to fiction. And sometimes there just is no answer to "what is this character doing in the moments we don't see them," just like the Simpsons... kinda don't have to live anywhere in particular, because there are really no "Simpsons" except for the actual moments in the show -- the "text" in lit-crit terms. (Well, except there are, but that's the "meta-text" and I have already rambled at you long enough, you are very patient and thank you. :) )

(*I have no idea if this is actually true. :) )

Of course, all this gets complicated for the furry crowd, where very often our characters live in our heads 24/7, and their lives are intimately tangled with ours! The leads in my webcomic are really just headfriends of my wife and mine, for instance, so they do have a tendency to leap in and rewrite themselves. :)

I'm not really saying that *that* sort of thing's a problem, if that's what you meant! If your characters have an independent imaginative existence that is completely awesome. :D And if you meant, like, giving them intricate backstories and motives and a life outside your plotline, that is also awesome. :D