Jeannette was introduced in the fourth issue of the ongoing Secret Six comic book as the sixth—and most recent—addition to the team, whose roster had changed many times over since its inception.

Jeannette was born into a family of impoverished nobility, and as a child was sent to serve Countess Elizabeth Báthory, a murderess.

When the Countess was imprisoned, Jeannette was assigned to care for her, and used the position to slowly murder Báthory by placing ground glass in her food.

[2] Her status as a villain was not made explicit, but due to her apparent relationship with her soon-to-be teammate Scandal Savage, it is implied that she had engaged in some unsavory business prior to her introduction.

Their relationship suffers another blow later, when Deadshot shoots Jeannette after she threatens to break a contract the team has entered into with a group of slavers by rescuing the imprisoned Amazon Artemis, whom she is shown to have met previously.

"[5] While the full extent of her sound-manipulating abilities have yet to be depicted, Jeannette has shown to possess at least some characteristics of the mythological banshee, including long life and a "death sense", which causes her irises to become black when someone nearby will die.

She has been shown to be a whole lot stronger physically than a normal human, snapping iron locks and chains with her bare hands alone, and at one point throwing an airplane wing at an enemy.