The Demon, The Dragon and The Wolf

Once upon a time there were three kingdoms with three different species: The Dragon, The Demon and The Wolf. They all used to live in harmony with the ability to shift into their creature and would prefer to stay in that form. From there they created their own kingdoms and had their own kings: The Dragon King, The Demon King and The Wolf King. The Dragon king was known to be the wisest, the Wolf King was known to be the most unified but the worst of the worst was the Demon King, who was known to be the most evil, deceptive and savage. Funny how they were actually able to create piece right?
Due to the uncaring Demon traits, the Demon King caused an uproar within the species. Unlike the rest, Demons only had one form and possessed deadly curses. So because of their greed and need to hate, they cursed the others, causing them to be forced into human forms, leaving the Demons with the power to conquer. That's when The Demon King decreed if anyone were to cross their territory or not abide by their rules, there would be severe and cruel consequences for their own source of entertainment. Therefore The Demon King created an empire, with him being on top, giving The Dragon King and The Wolf King less reign to rule. They were able to create their own tiny kingdoms as far away as possible from The Demon King so they can survive. Creating new lives with The Demon King in power was hard, but they managed and stayed put, until they could one day find a way to overthrow him once and for all.
Of course as time goes by each kingdom has an heir. The Dragon and Wolf king pull their forces together in hope that their sons can one day have the potential to overthrow The Demon King. But what happens if his son is bigger and badder than the previous threat?
And what of the legend of the Guardian who is said to protect and keep the piece within the kingdom?
Can the offspring of the three creatures create conflict or solve the past problems to unite the kingdoms again?

Not a fanfic