Is Kindred the Ruined King and Queen?
If you read Hecarim's new lore recently added, it says the king conjured a spell that bound their two souls together for eternity, and in Kindred's splash art you can see a dead king on the floor, possibly the ruined king shortly after the spell. Also when Kindred buys the Blade Of The Ruined King from the shop, it says "I personally tested this" which could refer to the sword the king used before they turned into Kindred and "forged in a land unwelcome to us" which could refer to the King being responsible for the current state of the Shadow Isles.
Anyways tell me if you see any flaws in your theories and I'm interested to see your thoughts.