Ellie’s been haunting Petrichor’s library since her her murder there in 1982. Even though she’s fully lucid and accepting of what happened, she’s unable to move on, bound to a reference-only book that hasn’t been looked at for decades.
She’s ended up becoming somewhat of an urban legend- using the hallucinatory powers ghosts have just to make herself a little less frightening. She’s happy to help library-goers find what they’re looking for, just to have someone to talk to.