Voldemort had won, and Harry was dead. It still caused one Hermione Granger grief to think that the love of her life had died before she could get up the courage to tell him she loved him. But that event had driven the path Hermione had taken, determined to destroy the Dark Lord at whatever the cost. He would pay for the death of all of her loved ones - Tonks, Lupin, Sirius, Molly, Arthur, Ron, Ginny, the twins, her parents, and especially Harry.
Following the battle at Hogwarts, Hermione had decided not to return to school, as it held far too many painful memories. She had taken her NEWTs during the summer, receiving an astounding 10 Os: Astronomy, Potions, Defense Against the Dark Arts, Herbology, Arithmancy, Ancient Runes, Herbology, Care of Magical Creatures, Muggle Studies, and Healing (which she had been studying on her own). She had, in fact, achieved the highest score ever recorded, shattering the record held by Tom Riddle, the famed Dark Lord known as Lord Voldemort.
Hermione had applied to the one position left into which the Dark Lord could get no insight: that of Unspeakable. Thankfully, all Unspeakables had to take oaths upon taking the position never to reveal the work they did to anyone living or dead. Even the people who entered the Unspeakable domain within the ministry took several binding oaths of secrecy. With her fame as the brightest witch of the age and her spectacular NEWT scores, Hermione was immediately accepted, and given an opportunity to design her own research.
Without hesitation, Hermione began to research time travel and began to train in several ancient muggle combat arts. As an Unspeakable, she was heavily trained in mind magics, developing her mental shields to the point that she was able to withstand simultaneous attacks from the five top legilimens in the department, and if someone were to, somehow, overpower her shields, she had developed a mindscape so detailed and dangerous that no interloper could traverse it safely.
She also took a position with M16, where she was taught how to use many different muggle weapons, how to dress to establish her superiority, how to fight in heels (which was surprisingly important, considering how often she had to wear heels), how to disguise her emotions, and how to lie. Hermione became one of their most adept intelligence agents within a year, and had helped minimize multiple threats of terrorism during her three years with the agency, after which she retired from M16 to focus on her efforts in time travel.
Less than a year after leaving M16, Hermione finalized her three main projects in time travel: manipulating a person's age permanently, or until the proper ritual was performed; travel to decades or centuries in the past, and travel into the future. After presenting her findings to her fellow Unspeakables, she requested permission to test her projects on herself. First, she completed a ritual that returned her body and energy levels to that of her eleven year old self while maintaining her extremely well-developed mental capacities and magical reserves (the greatest since Dumbledore, registering so far off the charts that no one was really sure what she could do).
After selling her flat and emptying her Gringotts account into her expandable purple purse, the one she had taken with her while searching for Horcruxes with Harry, she packed her belongings and began a ritual to take her back to the founding of Hogwarts. There, after explaining her very peculiar story, she was taken in by the founders.
Godric Gryffindor, the greatest Battle Mage in history, trained her in battle magic, teaching her powerful sorcery that had long since been lost. Rowena Ravenclaw educated her in wandless magic, until Hermione became so adept that she could do all but the most power-demanding spells with ease. Salazar Slytherin explained the history of the founders in great depth to her, as well as clearing up the rather muddled fact that he was not, in fact, the profound hater of muggleborns that all in her time thought him to be. Helga Hufflepuff led Hermione through the many branches of transfiguration magic.
Before she left them five years later as the most powerful sorceress in recorded history, they came together to offer her one final gift. Salazar spoke for the group, as he and Hermione had become very close during their lessons. "Hermione, my dear, we have decided to offer you one final advantage in your quest. Godric, Rowena, Helga, and I have put together a little something to make you a pureblood, as well as giving you each of our special powers. If you agree, you will become a parselmouth, have multiple magical animagus forms, have special healing powers, and be able to commune with plants. In addition, you will become our direct descendant and heir, so when you return to Hogwarts, she will do her utmost to assist you. Will you accept our gift?"
Hermione was loathe to abandon the last remnants of her muggle heritage, her blood status, but she knew that the benefits the founders' gift would bring far outweighed that petty cost. She accepted their gift with grace, thanking them profusely for their assistance in her mission. With that, she began her ritual, a ritual that would take her forward in time to one Tom Marvolo Riddle's fifth year at Hogwarts School of Witchcraft and Wizardry.