short summary: jalter is literally the wish-fulfillment of an obsessed, scorned man, gilles de rais. grieve-stricken by jeanne d'arc's execution, he used the power of the holy grail (which has the power to grant its owner any wish) to bring her back from the dead. however, what he conjures is not jeanne d'arc herself, but a concept of her. in his anguish he envisioned a jeanne d'arc that was enraged by the her captors that treated her as a heretic, of king charles vii for abandoning her, and god for misleading her.

thus, jeanne alter was born. she's nothing like her saintly half; she's obnoxious, arrogant, competitive to the extreme degree. she gets jealous easily and has no concept of interpersonal relationships, but that's because of the unique way in which she was summoned. she is insanely insecure for it, too, because she feels, correctly at that, that she has no identity of her own.

alter is a pretty complex character in that she yearns for veangeance but no amount of it will ever be enough for her, thus making her always feel incomplete.