With warfare never ending, a person can be an angel or a demon. All it takes is a change of heart under 2Masters that grant you powers to heal the world, or to destroy it.
READ RIGHT TO LEFT - Asian way
So its fine if she stays to possibly die and put him at risk but its not okay that when she refuses to leave with him that he go because of his own mission? Moments like this are why so I have grown to dislike so many female characters. -_-'