you were hired to protect Equestria. or more specifically 6 Ponies and their families so they could live a happy life. You kept to the shadows to avoid causing commotion. If ANY Pony in their terms saw you they would probably scream monster and run away. Until that one fateful day you had no choice but to reveal yourself. Because if you hadn't they all would've died and if that happened you would never be able to forgive yourself.