My theory is,
Zovaal was the originally the Arbiter, who resided within his own Realm.
For reference, I’ll just call this realm Eternia. (Eternal City)
Arbiter Zovaal lived in Eternia, within his castle Torghast. Torghast was originally the Karazhan of the Realm of Death. Filled with knowledge from all around the cosmic universe.
His helpers, paragons, servants, etc… were the Brokers.
But the Brokers, pre turning into their glowy eternal forms.
Arbiter Zovaal and his servants maintained order within the Shadowrealm, they made sure that souls were “categorized” and sent to their rightful place, they were in charged with the duties the Arbiter does now.
Arbiter Zovaal discovered something, or whatever happened, to cause him to rebel against the First Ones. The System was flawed.
Arbiter Zovaal asked his siblings to join him, to rebel vs the First Ones and “rewrite” history.
The Pantheon of Death refused, and fought back against Zovaal.
The result of the war was the actual destruction of the Realm “Eternia.” This shatter realm, became the Maw.
Torghast was the only thing surviving, and Zovaal had been banished to it.
Arbiter Zovaal’s servants, however, were treated as humanely as possible giving the circumstances. Using Kyrian magic, they erased their memories of being servants, and were scattered across the remaining First One’s outposts with no recollection of what had happened.
This is why they tend to seek knowledge but are usually absent from the other realms of the Shadow Lands. The Pantheon of Death don’t welcome Zovaal’s old servants into their domains.
The beings and creatures within Eternia, unfortunate enough to be there when the Realm was destroyed. Were sent into the In-Between to eventually be morphed into the Devourer creatures.