Violet Grey is the mistress of Viscount Campbell. She's first introduced in volume 5 in chapter 36. Men who are watching her say that she's a 'high class' prostitute worth 200 guineas a night. Since the Viscount is in debt she's not really being paid so she slepts with other men to support her lavish lifestyle as the Viscount's title is really the only thing that stops him from losing his house and other things.Near the end of the manga we're shown that since Violet was kicked out by Viscount Campbell she has moved on. The man who she's seeing wants her to move to France and whatever money is left that he has will be hers.