A magician never reveals her secrets. The Great and Powerful Trixie just happens to have a few more secrets than most magicians. For example, she’s actually a princess of Transylmaneia. And she may or may not have doomed Equestria to eternal night. That's not even the biggest secret, either.
An entry in FanOfMostEverything's Imposing Sovereigns II contest, for the prompt Trixie / Coronation. Set between seasons 8 and 9.