Esvele is a character played by guest star VividVivka. Her parents are Valen (deceased) and Valencia. The Rosznar family, former smugglers and slave-traders, are in Waterdeep trying to redeem their family name.
The outer skin of the Strahd doll was found in her home. How it came to be there is unknown. Esvele had approached the Waffle Crew at their home, hoping that they could help her enter the vault of dragons, where the hidden 500,000 gold pieces were kept. 
It became apparent to the heroes that Esvele sometimes operates as a masked viglante known as the Black Viper.
She showed up at the home of the Waffle Crew and subdued the Chicken Foot Coven, and then got into a chaotic melee with the crew, two drow, and a Zhent sniper.