In 1899, Esme was one of the first students who James Herondale met on his first day at the Academy. She joined James and another mundane student, Mike Smith, in the dining hall when she overheard that James's mother had been raised a mundane, incorrectly assuming that she Ascended. She curiously asked him about her Ascension, and he deflected the question by talking about his aunt's Ascension instead.
Esme expressed interest in changing her name—even her first name, which is not typical or necessary after Ascension.
During the following weeks at the Academy, she and Mike became friends with James, keeping him company during lessons when he had nobody to sit with. However, after James showed his ability to Change into a shadow, both Esme and Mike began avoiding him and whispering behind his back. When James began to spend more time with everybody's favorite Shadowhunter Matthew Fairchild, however, Esme apologized to James for her and Mike's behavior. She also asked him to put it a good word about her to Matthew as she apparently liked him. She later visited him at the infirmary when James got expelled and promised to "look him up" once she had become a Shadowhunter.
- Nothing but Shadows (first and only appearance)
- A character of the same first name, Esme Hardcastle, was featured in Chain of Gold. It has yet to be confirmed if they are the same character.