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.
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.