Well, I got an idea recently:
Depending on how the person eliminates the enemy, the rest of the enemies will act differently upon them. Everytime they kill an enemy in a skillful way, their threat level increases. Every time they kill it in a slow, weird way their threat level decreases. The enemies will use different skills, items, or other sorts of things on them depending on their skill level. :/
Sound good?
How would you determine "skillfull ways," because that could be debated for quite some time. Not saying that it isn't possible- maybe the enemy has an element attribute and you killed a water enemy with a lightning spell. Or maybe it was an enemy with high defense and you killed it with some "armor piercing" or magic attack.
On the up-side of this, I had already come up with this idea(though I won't doubt you thought this up for yourself, since I never published such info) and I do think it is a good idea. I've got an idea for an RPG, but it's on hold until my graphical skills improve...greatly. As a matter of fact, both of those examples I gave were taken from my idea on such an AI system.
Hiead