Harry Potter and the Witch Queen

After a long war, Voldemort still remains undefeated and Hermione Granger has fallen to Darkness. But despite having gained great power in exchange for a bargain with the hidden Fae, she is still unable to kill the immortal Dark Lord. As a last resort, she sends Harry back in time twenty years to when he was eleven, using a dark ritual with a terrible sacrifice. Canon compliant AU.