That's a cool idea. I kind of thought the same, except its more of the enderknights turning the Ardoni clans against each other 300 years after the second great war. The enderknights did this to take over the Ardoni provinces, and by directing their hatred towards each other's clan, they were able to weaken them and take over.
I'll lend some of my OCs ^^
Lorveth Kaltaris - The son of the Kaltaris master. He is a young adult male whose ideologies and personal beliefs of the Voltaris differ from the rest of his clan. He views the lot as refugees who crave redemption and acceptance, and hence, has a softer approach on them.
Ephyra Voltaris - A young adult female who is driven by anger from the years of torture and trial. Her backstroy has shaped her both physically and mentally, and has pure hatred for the other Ardoni clans. (Half of her face and her shoulder burns with an eternal red flame, making her look menacing in the eyes of the other clans)
Ione Mendoris - A middle aged female Ardoni who served as a war nurse during the nether invasion in her teenage years. She was forced to serve as a spy during the great war, and during her time navigating the Voltaris camps, she grew sympathy, eventually taking a young baby Voltaris in during a raid, and raising him as her own in Mendoria.
Feel free to change the backstories according to your story. Please give credits though if you do end up using them. I hope this helps