Cassie is the main protagonist of Ruin, the Free DLC for Five Nights at Freddy's: Security Breach. After receiving a message from her friend, Gregory, to encounter him in the now abandoned Pizzaplex, she soon finds out that he was Kidnapped and goes on a quest to try and save him, while avoiding the remaining dangers that still lurk within the place.

Cassie is a human child with brown skin, amber eyes, short brown hair with puffy pigtails and green painted nails. For attire, she wears a red sweater with a white polo underneath, cutoffs, black leggings, white socks and purple sneakers.

Her color palette is heavily based around Roxanne Wolf, who happens to be Cassie's favorite character in the Pizzaplex.