Actually, I thought about something.
One thing that I like aesthetically in War for the Overworld over any Dungeon Keeper is the heroes are pallete-swapped to look more evil if you convert them (but then again, at the time DK was made they didn't had resources/time for that). But since you can also put a Underworld Gateway for the Empire and still spawn Gnarlings and the like for them, I thought "what would they look like if they were more 'goody-two-shoes'?".