This story presents a what if scenario.
What would have happened if Thorax had sought out Princess Cadance and Shining Armor upon reaching the Crystal Empire, instead of hiding in the frozen wastelands to be found by Spike? Would the Crystal Ponies be willing to accept him, or is he getting in over his head? More importantly, what will the two rulers, the same whose wedding was almost ruined by his kind, decide to do with him?
Takes place before the episode The Times They Are A Changeling, and of course retcons what happens in said episode.