Vyerith is a doppelganger that seems to work for the Black Spider. The Party found her at Bloodshield Keep, torturing Gundren Rockseeker while disguised as a female Drow and attempting to take his visage, but they managed to fight her off before she succeeded.
Vyerith shifted into goblin form and fled into Neverwinter Wood.
The party later found and killed her at Wave Echo Cave.
While questioning Nezznar, The Party finds that he was unaware of the Dopplegangers and believed them to be Drow. The Party believes it is likely that they were in service to House Xorlarrin and that Nezznar's mother, the matriarch of House Xorlarrin, paid them to follow her youngest son and report to her.