This story is a sequel to Celestia's Resignation

Twilight has ruled Equestria for over one thousand years. She always remembered how she became ruler. Celestia left her this role because she had to leave equus and assume the role of queen on a distant planet. She still wished Celestia had stayed. At least long enough to help her along the path of being a ruler. Today however she was going to see her one last time.

Once every five hundred years in Equestria an event occurs. It is no festival or holiday, it is the blood moon. The first recorded incident of the blood moon was three months after Luna was banished. During the first blood moon there was widespread panic throughout all of Equus. Monsters from all over the world ventured from their homes and wrecked havoc upon all nations. Many were killed during this time. Most were military personnel that fought to protect their homeland from the monsters that threatened them. The terror every nation felt died when the golden sun broke the horizon ending all of the monsters rampage.

A search for a mysterious energy reading leads a Commander to Equestria and reawakens some of his memories from a place he once called home, but his presence there is not welcomed by some of the nations.
(Note: rating may change later. Also the sex tag is for certain situations)

Celestia leaves Equis after ruling for over a thousand years. She is also an alien that was sent there. Who could have guessed that? Now this story has a sequel view it here .