That's awesome, anon! Well done!
I have a theory about Princess.
Why was Vladok willing to shatter his own mask? He did not seem the suicidal sort, he seemed the wily survivor sort. I mean, how old must an Ebon devil BE to show signs of age?
Plus, doesn't it seem odd that there's two Ebon's fallen and bound to Allison? Aren't those guys rare?
Cio is fairly well explained: She's around because White Chain went and found her.
I think that Vladok was stalking the Key of Kings to increase his power... because Vladok was once Himself.
What, you ask?! Isn't Himself the King of Devils? Yes, but he's also stuck in a hurtbox with a dozen badasses keeping him down.
I think that Himself worked some scheme, inside the box, and deliberately bound His own flame, and took on the name Vladok, to get out of prison. I suspect he probably switched places with another devil.
Why do I think this? An experienced demon binder exclaimed at the vast size of Vladok's flame. Indicates huge power which is not in line with Vladok being old and shriveled.
Vladok broke his own mask, why? Because he knew he could keep Himself together long enough to easily kill everybody present and take the Key of Kings.
Why was Vladok there at all?
I suspect Vladok/Himself has been stalking Zoss! He probably saw Yabalchoath get her hands on a sliver of Mammon's power, and decided it was time to graduate upwards from King of Devils to Black King of All Universes.
He slipped his prison, making himself an Ebon, and has been stalking Zoss. When Zoss dumped his Key on Allison, Vladok bided his time until she came back out of the sealed dimension of Earth, and as soon as he found her, challenged her to get at that sweet, sweet key.
Vladok/Princess IS HIMSELF.
I bet Allison binding him was a horrible, horrible surprise.