In "Immune to All But Justice", there's a brief back-story with her being a troublemaker like Fillmore used to be, as seen via a flashback of them dangling another student upside-down to steal loose change that falls out of his pockets. And like Fillmore, she is now reformed (or so she seems to be, anyway, at first). Currently, she serves as an assistant to Winston Kotter. After Fillmore meets up with her again, they do a little catching up with each other. Ingrid thinks Fillmore seems to have a thing for her, but he denies it.