Anastasia Tremaine

Anastasia Tremaine is one of the sidekicks imprisoned on the Isle of the Lost. She is the daughter of Lady Tremaine, the younger sister of Drizella Tremaine, and stepsister of Cinderella. She is now the mother of Anthony Tremaine and aunt of Dizzy Tremaine.

Cinderella
Before being sent to the Isle of the Lost, Anastasia Tremaine was one of the daughters of Lady Tremaine. After Lady Tremaine married the father of Cinderella and he died, Anastasia like her sister and mother, began treating Cinderella not as a step-sister but as a servant or slave. She best demonstrates her disdain for Cinderella when she rips at Cinderella's attire part of which consisted of an item which she had discarded but did not wish Cinderella to have to wear to the ball. Later when the proclamation was made that whomever the lost glass slipper could fit on would be the person Prince Charming would marry, Anastasia tried to convince the Grand Duke that the slipper belonged to her. However when it did not fit, this lie became evident. At some point after Cinderella married King Charming and moved into the castle leaving Drizella, Anastasia, and Lady Tremaine. she along with her mother and sister were sent to the Isle of the Lost for abusing Cinderella. Anastasia like her sister has multiple children which leads to the conclusion that while on the Isle of the Lost, Anastasia found someone to marry

Trivia

 * Her (as well as Drizella's) crimes are abusing Cinderella as a maid and destroying her mother's dress.
 * In the second and third Cinderella movies, she turns good and lives happily ever after, but in The Isle of the Lost: A Descendants Novel she's still a villain. The same fact rings true for Iago. This might mean that the sequels/spinoffs of Disney movies don't exist in the Descendants Universe.
 * She, her sister, and her mother are the few villains on the Isle who weren't brought back from the dead, along with Captain Hook, Cruella De Vil, Governor Ratcliffe, Yzma, Shere Khan, Jafar, and Madam Mim.
 * Captain Hook, however, is an unknown case because his last shot is him running from Tick-Tock the Crocodile, but it's never implied he is actually eaten.