Not sure if this should go in GD or Treasure Vault. Oh well.
Theory: Connection between Almire, Scarlet Fortress, and Candlestick Keep
Margrel/Margel, said to be the unluckiest Kat of all, is said to have brought about the destruction of the Owlites and the damnation of the Kats. Right? So, here's what happened:
-Kat Tribe, Owlites, and Almire are fighting.
-Kats attack Owlites, in the raid described by the Kat gear during the Black Kat event.
-Margel opens the Book of Grey Feathers.
-Margel reads the book and gains knowledge of the Owlite Magics, which combined with the Kat abilities gave him the power to unite the Owlites and Kats and attack Almire.
-United army approaches Almire.
-Vanaduke sees it coming, flees into mountains, gets cursed, blah blah blah.
-Vana comes back as a fire demon. Owlite/Kat army runs away.
-the Owlite kingdom is closer to Almire, so it gets destroyed and all Owlites are killed.
-the Kat kingdom is farther away, and before Vana reaches it, Margrel attempts to use his new powers to save the kats.
-It turns out Owlite Magic and Kats don't mix well, and combined with the fact that Margrel is inexperienced and desparate and that an ant walked into the ritual circle (hence the unluckiest Kat of all), he instead creates a curse, cursing all Kats to forever wander the living world as ghosts.
-Most are turned into the normal Spookats and variants we see today, but those who set foot in Almire are turned into Grimalkins.
-Grimalkins go to Candlestick Keep pursuing Vana and the Owlites, who they now see as traitors.
-Black Kats were a by-product of being in really dark places when the curse hit and too much negative energy to start with, as well as the Kats that were close to Margrel when he cast the curse.
-Scarlet Fortress is Scarlet because Vanaduke approached the castle seeking revenge, but realized all the Kats were dead anyway and left. He didn't get close enough for eternal flames everywhere, just a red tinge in the air.
Does that make sense? :D
EDIT: Added Grimalkin and Black Kat creation.
Not quite. According to the lore, the Kats and the Owlites were at war with each other. Margrel found the book of owlite magic, and read it, casting a spell that destroyed the owlites, and turned all the kats into spookats. Therefore, they could not have been the two kingdoms that attacked Almire, as neither the kats nor the owlites could have had the resources to attack Almire, as they were in constant conflict with each other, and therefore would never have been able to unite. The gremlins, however, could have had ancient medieval ramparts and kingdoms during this time period, as their civilization would have had to come from somewhere, and we know that the slimes have had a monarchy established for some time now, but there is little evidence that either of these two had anything to do with Almire. There are some references to another kingdom,however. The ancient plate set mentions the armor being worn by titans. The ironmight shield's crest's meaning has been "lost in time". I believe that the answer to the question lies within the plate sets. The ironmight crest is similar to the Almirian crest, but it simply cannot be the same crest of the same kingdom, as why would there be two different sets for one kingdom: the ironmight and almirian crusader? So who were the plate user's, or as I like to call them, the ironmights or the titans, we may never know, but I believe that they are likely the kingdom or kingdoms who attacked Almire.
As for the Scarlet Fortress, that is a difficult question, with no real answer that we can find.
Man, we need to make a timeline for this stuff. It's confusing.
~Magnicth the Magical Bush