Swirler of Silver

Harry died, and as a result the wizarding world is thrown into massive chaos. Azkaban echoes with bitter laughs from prisoners. The Ministry is hopelessly taken over. The house of Black...let's not go there. But with deceit comes a certain unfound secret. Who is this girl that was purposefully kept in Hufflepuff to fool even the professors in estimating her skill? How did she survive all these years with... Voldemort as her teacher?