Everypony knows of Twilight Sparkle, Princess of Friendship and previous star student of Princess Celestia. But do many know that Celestia has taken many students in her years of being a ruler? Before Twilight Sparkle, before Sunset Shimmer, there was a stallion called Moonstone. A devoted student with a drive to learn his magical studies and his studies of the cosmos, he could never be without a good book or be far from his telescope and charts. Though when the time came for the final phase of his studies, the final test, he felt unprepared and departed to study in solitude.
For years he never wrote or spoke a word to Celestia, but finally he has returned, feeling ready for his test. However, he soon discovers that not only has his final test opportunity passed him by, but that somepony else has completed it. The newest princess and his third replacement. Twilight Sparkle. Having nothing else, he concedes to studying the stars in the Canterlot Castle Observatory, his once loved home in the castle. But when Twilight discovers she has a senior in magical studies who might even know more than her, she jumps at the opportunity to potentially be his friend. Moonstone, will hear nothing of it.