NPCs taken as spoils by the victorious orcs at the end of Rosetta's Faction Wars.
When Rosetta's Faction Wars ended and the orcs made the transfer to the Scolopendra Club, they took the librarians and other NPCs as spoils while mocking the surviving crawlers through the glass.
It was that seizure that Brooks tried to stop, casting spell after spell at the portal screen in his rage — and it was in that moment that King Rust lassoed him and pulled him through the glass. The taking of the librarians is thus the direct trigger for the death that shaped Rosetta's entire life.
The NPC spoils whose seizure provoked Brooks's fatal defiance.