Princess Celestia understands that being an Element of Harmony is dangerous, and that Twilight and her friends are bound to make enemies. So, naturally, the only course of action is to send a guard to keep them safe, even if they don't know about it.
Dark Flame was a young stallion of the mining village, Stonewall. But after a dragon thought to be of myth attacks, Dark becomes the only survivor and now attempts to remake his life. However, his past isn't willing to let him go so easily.