Isabel, growing up in a convent, was deemed as a potential assassin by the Chief Inquisitor when she was only four or five years old, and then was taken back to the Inquisition, where she started learning to spread the ideal grace in some strange way—assassination.

With a pious bone in her body, Isabel has been convinced that everything she does is to better spread the ideal grace. She believes that those killed are not really dead, but just exchange their physical demise for spiritual salvation.

When executing the ideal grace, she always puts on an innocent look, which allows her to easily approach her targets. When they let their guard down, she will mercilessly terminate their life while praying devoutly that their spirits could be saved.

Rumor has it that the forbidden magic reappears in the Chrono Tower. After hearing that, the Holy Church seeks help from the Inquisition and has Isabel work for it, outwardly claiming that Isabel would assist the Preacher in search of the Sacred Relic. But the truth is that Isabe is ordered to terminate all those trying to engage in the forbidden magic.