It has been some time since Luna has returned. She has her own guards, her own duties, again. She even has her own festivals.
She also has her own fans.
So when an all-too familiar scenario plays itself out from the other side of the mirror, Luna enlists one of her most "faithful" subjects to collect a motley group of ponies to do their duty for their country and help out whenever they can.
Of course, all the solitary archivist has to work with is an obsessive gambler, a not-so-quite-zen martial artist, a hard-drinking retired soldier, a cellist, and a member of the guard who aspires to be everypony's knight-in-shining.
We're all quite possibly doomed.
[This is a legacy story from my Fanfiction.net account, and follows cannon up to the end of season one. Yeah, it's old. I haven't updated it in a long time, but, like Johnny Spurs, if there is interest I will pick it up again. Featured on EqD years ago.]