The Shadow Knight was originally developed by Mike Rayhawk as a single character who would act as Vladek's Dragon. In the final story, the Shadow Knight was demoted from a single Dragon to an army of Brainwashed and CrazyFacelessMooks.
As shown here, Mike Rayhawk's original concept for the Castle of Morcia would have had more than just blue and red transformation to show whether King Mathias or Lord Vladek was ruling Morcia. Under Mathias's rule, it would have had a lion-shaped gate, and under Vladek's rule, the entire castle would have had a a scorpion-like appearance. When LEGO expressed doubt that such a castle transformation could work without taking it apart and rebuilding it, Mike Rayhawk proved them wrong with an animation mock-up in Maya, showing the lion castle transforming into the scorpion castle without need of disassembly! In the end, though, the final product was simplified so the transformation of the castle was limited only to changing the colors, not the appearance, of the castle.
Daniel Lipkowitz, the writer of the Knights' Kingdom storyline, goes by the username of Swiftone on BZPower and answered a lot of fan questions back in the day. One of the more amusing trivial tidbits he revealed was the names of King Mathias and Lord Vladek's horses: Leo and Pinchy, respectively.
Mike Rayhawk, who did a lot of artwork and concept sketches for Knights' Kingdom, also provides a ton of Word Of God information and insight on his website.