Evolution of a Game World

I have often gone on and on (and on and on) about allowing your game world to not become stagnant, but instead letting the years roll by. Let the nobles marry and have kids. After a major war, have an uneasy period of rebuilding. Allow other organizations to grow in the spaces left open after your adventurers destroy the previous groups. But there is another way that you really need to let your world grow - let it evolve. What I mean isn’t obvious. Let me use an example: I made up a barony, back before I was married. The baron was a wimp and his father pretty much still ran the barony, but by intimidating his son into doing what he wanted. The barony had been turned over when the father had an illness, which he never recovered from and is now bedridden. But he screams from his bed until his son comes in and promises to do everything the father tells him to do. This of course is a bad idea because the father isn’t out there mixing with the people or the other nobles, and has a VERY skewed perception of what is going on. Anyway - The baroness was supposed to be this nice, kind of mousey woman - a match to her mousey husband. Truth be told, when we were role-playing the baron hiring a party, I forgot to include his wife. I just forgot she existed. After all, I had named her probably 4-6 years prior, and cannot be expected to remember everything. So later on, when I sort of had to explain why this baroness who did not seem to exist now existed, I said that she had been ill during the earlier meeting(s). Well, that kind of took root. She happened to be ill a lot! Through role-playing the NPCs, I converted a boring mousey character into a woman who controlled her husband through the passive aggressive use of her hypochondria. She is always pretending to be sick in order to get his attention, to avoid going where she doesn’t want to go, to avoid eating foods she doesn’t want to, etc. Now - She’s interesting! Now she is hated more than most of the villains I write, because the baron is actually a nice sort of guy and the players have taken a great dislike to the way his wife and his father abuse him. Hopefully that helps to describe the sort of evolution I mean: Just because you wrote that the NPC was a certain way doesn’t mean they have to stay like that, especially if they have not yet been revealed to the players. Changes on a whim are OK too. And if it doesn’t work out, then you can explain to the players something along the lines of: No, you met her during a really troublesome period. She was a real bitch that season because of other things, but she’s healthy again now, and her nicer personality has returned. They don’t have to believe you, but that’s part of the fun too - when different players have different perceptions of the same NPC.