Astrid Pertridge is a pre-made Sim who lives in Hidden Springs. She is the oldest daughter of Lonnie Pertridge, sister of Eunice Pertridge, and stepsister of Ella Carlisle. She is the only one among her mother and sister to be friends with Ella; this might be a reference to the Disney adaptations of Cinderella: in the sequels to the original movie, one of the sisters, Anastasia, slowly becomes friends with Cinderella and slightly turns against her mother, disapproving of the way her mother and sister treat Ella. She works as a Fan in the Music career track, level one. She has always dreamed of becoming a princess. It is also mentioned in Hector Mendoza's bio, who also works in the Music career track, that he might have come to Hidden Springs in order to encounter a young and mostly wealthy debutante, who is highly likely to be Astrid.
Astrid and her sister Eunice are thought to be a parody of the cruel stepsisters in the fairy tale Cinderella. Eunice and Lonnie's fondest wish is to see Eunice marry the "prince" at the expense of the goodhearted stepsister.
In A Cinderella Story, Astrid is the name of a classmate to the Cinderella character, not a stepsister. She ends up in a relationship with another character, Carter. It is possible that the game is implying that Liam O'Dourke, who may be based on the Carter character, and Astrid will become an item.