HP: The Good Side of Black

Harry and Ron are whisked away before they can rescue Hermione and torture does not even begin to describe what happens next. Bellatrix has a Brilliant Plan of sorts, when Harry and Ron are rescued, but Hermione is not. She forces Hermione to drink a polyjuice potion. Transformed into Sirius, she is delivered to Narcissa, for the purposes of creating a true Black Heir.