How much could the Witch possibly know about Hamlet?
From what Grendel relayed of the Witch's words, it was clear the Witch's main complaints were accusations against the scumbag ancestor; she truly had little understanding of the territory.
The exchanges between the Witch and the old ancestor primarily concerned Herbology and certain Clairvoyance arts. Their relationship deepened, and only then did the ancestor, smitten with the Witch, share his secrets. This ultimately drove her mad.
Having learned all he could from her, the ancestor then heartlessly cast her aside and turned his attention to studying Necromancy.
As for why these two individuals ended up collaborating again?
The reason was simple. Lance had brought back a large population and resources from Totnes. Once these were invested, Hamlet's development skyrocketed. Its subsequent outward expansion threatened both the Witch and the ancestor.
