In S9, After King Sombra's horn was found in the Crystal Empire, the princesses have decided to resurrect him and reform him. The pony to reform him will be none other than... Fluttershy!
Fluttershy is faced with the task of caring for King Sombra, this time without the protection of the Princesses. Will she be able to reform him, as she did Discord, or will his dark will overwhelm her?
Fluttershy must make a choice she never thought possible. To stay in the world she had always known or to enter one she never thought possible. But she may not have had a choice to begin with.
Before Sombra became king he was a simple scholar attempting to give Earth Ponies an equal standing amongst unicorns. He didn't expect his quest for power to cause him to meet the one he could not live without. But his hunger for power still calls.