In Episode 19 of CEREBRO, Connor and artist Valentine M. Smith analyze the X-Men's living computer, Sage! Introduced in 1980 as Tessa, a mysterious Hellfire Club attaché, a major retcon in 2001 revealed her to be one of Xavier's original students, kept apart from the X-Men and deployed as a spy.
The CEREBRO character file on Sage begins at 1:12:36.
(Content Advisory: Tessa's story includes sexual violence, sex trafficking, and torture.)