After the prophecy has been fulfilled and the Elements of Chaos have been awoken, there is nothing stoping Twilight from waging war with Equestria, and the only goal in her mind is to conquer all of it.

Twilight Sparkle is now a changeling queen. At least, she's supposed to be.

Twilight Sparkle: a name often associated with magic, friendship, harmony, and most recently, ascendant princess of Equestria. Nopony, not even herself, could have thought that she would be a changeling.

When the circus comes to town, Twilight decides to see the show but a certain magician has other ideas

Discord has won...all that remains is to create a pony who will cause chaos in Ponyville.

Twilight Sparkle finds herself plagued by frequent Nightmares. Unable to sleep, and believing an old enemy is responsible for her restless nights, she sets out on her own to confront the Darkness, only to fall victim to it.

A thousand years ago Princess Celestia banished her Nightmare corrupted sister to the Moon. But she did not comprehend that The Nightmare ever had a Daughter.

Twilight had an exhausting day and she just wants to rest, but Spike annoys her!

Twilight meets Sombra and joins the dark side.

King Sombra uses the Cutie Map to travel back in time to abduct an infant Twilight Sparkle and raises her as his daughter.

Twilight Sparkle was like everypony else besides the fact of being an alicorn princess. However her life turns around when she finds herself in the hands of a group of villians that change her into Equestrias new Villian.

A new Queen must be chosen, must be born, to reunite the disjointed Changeling Swarm.

Sombra was weakened by the crystal heart, allowing him to subdued and captured. Twilight decided to learn more about her foe. As she persists, however, something happens between them.

King Sombra forms a new plan for taking over Equestria--he just needs to take over Tartarus first. But before that can happen, he needs a queen. And he decides Twilight Sparkle is perfect.

story about Kng Sombra and if he corrupted the crystal heart