Everything Happens For a Reason Part One- The Return

Nightmare moon knew what she had to do. From her place in the shadows she had watched Celestia for months now. Learning of all the important events in Equestria, the perfectly timed moment when both sisters would be in bed, sleeping, oblivious to her plans. She had to latch onto Luna's soul without her realising. By the time she woke in the morning, it would be too late... but Celestia had ruined that! Just as Nightmare Moon had detached herself from Celestia's shadow and opened the window to make her escape, Celestia had woken up. Just in time to spoil everything Nightmare Moon had been planning for months now. But, no matter, she was here now, Celestia outside, and Luna asleep. Nightmare Moon used her magic to to steal into Luna's mind, body. and soul.