The Sparkles are a very old Canterlot family. Like any old family they have traditions. One of these traditions is that a Sparkle must do noble deeds to win their love-a tradition going as far back as Sir Prancealot. These are the noble deeds Lady Twilight Sparkle did to win the hoof and heart of Princess Celestia.

Now has a sequel! (https://www.fimfiction.net/story/362471/seasons-of-the-heart)