Shadows Linger Edit
There were several people who delivered bodies to the castle for money, including Raven, Marron Shed, and Lisa Daele Bowalk. Two unidentified Rebels who had been arrested by the Black Company and who were interrogated by the Taken, admitted to selling corpses to the castle as well, but in much smaller quantities.
The Black Castle was actually a portal designed to free the Dominator upon completion. The Dominator's minions managed to spread the seed of the castle through amulets given to several people, including Marron Shed. The amulets kill their hosts unexpectedly and begin growing a new Black Castle.
The castle in Juniper, the only one that grew to significant size, was destroyed by The Lady and her Taken at the Battle of Juniper. During this event, the Black Company suffered hundreds of fatalities.
The proto-castle, and "seeds" Edit
A much smaller proto-castle, outside Meadenvil, was also in the process of growing. This one was reported by Croaker to The Lady, who had it destroyed. The last remaining "seeds" were stuffed by Croaker into the mouth of the barely-living Limper, for The Lady to find and destroy as well.