Esvele Rosznar was a member of the noble Rosznar family of Waterdeep. Raised to be the perfect noble woman in an attempt to repair her family's sullied name after their banishment from Waterdeep, she eventually rebelled against her noble upbringing, embracing the legend of the Black Viper.
Esvele was fully aware of the danger she put herself and her family's name in every time she went out in costume, but that did not deter her. She rested well satisfied that at least one member of the Rosznar family was earning the respect they deserved from Waterdeep's nobles.
In the late 15th century DR, the Rosznar family returned from their banishment from Waterdeep after being convicted of slavery 100 years prior. But they were unable to regain the respect they'd lost due to the scandal that got them banished in the first place. Many members were resentful of the loss, rationalizing that all families had skeletons in their closets and they were just unlucky that a family squabble had let their secret go public. They argued that the slave trade in Amn remained in good standing, as well as in other locations.
When she was younger, Esvele partook in dance lessons, proper etiquette, and poise, among others. Her education was intended to make sure that she was worthy of her title and position. She openly rebelled against her family's wishes, but when met with resistance she changed tactics. She taught herself to pick locks, pick pockets, move silently, and even fight. She was the perfect daughter by day, but by night she hid her identity with hoods and masks, snuck out, and cut loose.
Esvele's escapades around the city of Waterdeep came to prominence when she embraced the title of the Black Viper, making her own costume to complete the transformation into the famous criminal who had died 100 years prior. Often she needed do nothing more than throw back her cloak and reveal her costume to have nobles throwing their money at her and running, maybe brandishing a dagger if they were brave. Though she understood the dangers of taking on such an identity, she knew how to fight if it came down to it.