The pretty angle and the boy from hell

Lucy is on a mission to make a boy from hell become a great boy and make him come to heaven, she thought she could make the mission but she realize that it's harder then she expect, they start to get closer together and fall in love but there is a law that hell people and heaven people can't date, she try's to complete the mission but she can't she always get lost in his eyes trying to find a way out.if she dates the boy she will become the wings of darkness but if she complete the mission and change him she might be with the boy she did not fall in love with so now she haves to choose between love and become wings of darkness or will she complete the mission and suffer from loving a guy she don't even know?