In September 2007, her nephew Sebastian went to Idris to represent the Institute at an emergency Council meeting about Valentine Morgenstern. While en route, he was killed by Valentine's son Jonathan Morgenstern so he could take his place.
While in the guise of her nephew, Jonathan killed Max Lightwood in the midst of the Mortal War. Upset and disbelieving, she sent the Penhallows pictures of Sebastian to show the Lightwoods that whoever killed Max could not have been Sebastian.
- According to Jonathan, Élodie has a vast network of informants that keeps her updated in Idris even though she seldom goes. He also said that she collects spell books and dislikes leaving the Institute. Whether there is some truth to this or was made up by Jonathan is unknown.
- Earlier editions of City of Glass referred to Élodie as "Aline's father's sister"; this line was later corrected to "my father's sister".