Replying...
Intro. Cassidy was a child murdered by William Afton, who lured her by wearing the Spring Bonnie costume—deceiving her and four other children before killing them and stuffing their bodies into animatronic suits. She was placed inside Golden Freddy (also known as Fredbear), where she encountered Evan, another lonely child trapped within the same animatronic. As Cassidy slowly accepted she could never see her parents again, her grief turned to vengeance. She wanted to make her killer suffer, to inflict the same pain he had caused her. Over time, she bonded with the other missing children: Gabriel (who possessed Freddy Fazbear), Jeremy (Bonnie), Susie (Chica), and Fritz (Foxy). Years later, William Afton returned to the now-abandoned Freddy Fazbear's Pizza to dismantle the animatronics. He destroyed Freddy, Chica, Bonnie, and Foxy before being pursued by their vengeful spirits into a safe room—where the decaying Spring Bonnie animatronic sat waiting...

Cassidy

@Kris