She has magical powers that can enchant people. She almost marries King Gregor, but is stopped by Sunni, who figured out that sugar is her only weakness. She usually appears as a beautiful woman, but this is merely a deception; her true form is that of an ugly, green-skinned hag.
She is named after the confection marzipan, which primarily consists of sugar.
This is ironic on some level, as sugar is her only weakness, and causes her to revert to her true form.