Vermouth's background is very mysterious because she has been secretly living at least two lives through the art of disguise: that of actress Sharon Vineyard (now "deceased") and her supposed daughter, Chris Vineyard. 

As the actress Sharon Vineyard, Vermouth gained much fame on Broadway and in movies, even winning an Oscar. Even then, she was a member of the Black Organization. Twenty years ago, she murdered Jodie Starling's FBI father who had collected information on her. Jodie Starling would eventually grow up to be an FBI agent and one of Vermouth's most bitter enemies. As Sharon, Vermouth became close friends with Yukiko Kudo back when they were studying disguise under Toichi Kuroba.