Ava Ray, named for her wings and the way the sun made her mane glow, has had lots of big dreams throughout her life. The more she heard, "You can't," the more determined she was to prove she could. Now that Ava is all grown up and working as a teacher, she gets to watch little foals discover their own purpose. And yet... She is still seeking her true destiny. But each path seems to lead to a dead end. For the first time in her life, she might be running out of dreams. Maybe they were right. What am I here for anyway? Do I even have a dream anymore?

Twilight Sparkle is successfully fulfilling her destiny as the ruler of a kingdom somewhere. Although she has continued to write to Princess Celestia consistently, the latter has distanced herself in recent years. Twilight writes one final letter to her teacher.
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Personally, I prefer the first chapter on its own, but the story does continue in the rest.
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Part 4 in progress!