Harry doesn't stand a chance against the forces of evil - he doesn't know that but many others do, including a younger pureblooded girl who doesn't want to lose everything. Astoria Greengrass intervenes on his behalf and forms an attachment along the way.
Harry saves Narcissa and her daughter Lacerta (FemDraco) from a stint in Azkaban. Lacerta saves Harry from solitude. Narcissa just gets to benefit from both of them. Harry/FemDraco and from what my Beta tells me, it's fluffy