Astarte

Duchess Astarte is the twin identical sister of her brother Astaroth. The two twins are able to share the same body by being able to alternate back and forth, from a curse placed by Lucifer by Astaroth's own request which was done by using a two-headed hermaphrodite snake. When Astarte takes control of the body, it becomes female and Astaroth becomes trapped in the black snake, and when Astaroth becomes in control the body becomes male and Astarte becomes trapped in the white snake.