Madeleine

A magician who claims to be from a distant land. As a stranger arriving in the capital, she drew much attention for her wondrous magical abilities that seemed to transcend both the arcane and divine. Claiming her powers were all granted to her by her mistress in that distant land, she became somewhat of a sensation. In reality, she is a centuries-old warlock who serves the @Queen of Shadows, working against the revival of the Demon King.

Two centuries ago, there once lived a witch in the deserts near the village of Zalambur. The villagers treated her with a mixture of fear and respect, and kept their distance. The witch had no problems with this arrangement, and kept to herself.
tl;dr something bad happened and the villagers chased her out
She was forced to escape into the desert wastes, and wandered for seemingly countless days and nights.
She was at the edge of death when she finally reached the end of the desert sands. She had traveled all the way to Land of Shadows before finally collapsing.
Her life was saved by the Queen of Shadows. However, it came at great cost: she no longer aged, she lost her original memories, and she was no longer able to feel emotions... Is she alive, or is she just a walking corpse?
She became a servant of the Queen of Shadows in gratitude for her life, and was able to learn some words of the Astral script, enough to understand the prophecies of the heroes' return. However, she lacked any motivation to do anything else, and did little for the next 150 years.
Finally, after hearing troubling news of the forces of darkness stirring into action once more, the Queen of Shadows sent her back across the desert to find the rising heroes and stop the demons' plans. Hopefully, she would find a new purpose in her artificially-extended life helping others.
She became convinced Reiter and his group were the heroes of legend and attached herself to them. Now, she sits around their house and eats their snacks, occasionally offering cryptic guidance.
She often flirtatiously teases those she meets in an effort to feel something and get a reaction, but her advances have no greater meaning behind them.