She seems to be in an altercation with Ariane.
Has she fallen to madness?
A deceased hero and veteran adventurer.
During The Blood Pact you must help her save a young woman from being sacrificed by a group of Zamorakian cultists. After the quest, you can claim a Helmet of trials from her after obtaining 300 Quest Points.
During Heart of Stone you must track her across Gielinor with the help of Kipple after she steals Ariane's research and murders one of her friends. Towards the end of the quest you'll confront her and learn that she is trying to prevent the Elder Gods from ever awakening, but this will result in nobody being able to use Magic anymore and as she refuses to stop, Ariane fires a spell that knocks Xenia into the Abyss, resulting in her death.
After Heart of stone, She is replaced by Wizard Ilona in Lumbridge.