On the day before the final Summer Sun Celebration, Aita is playing cards with Cozy Glow and Spike when all three are invited in secret by Shining Armor to Canterlot Castle so that they may participate in a scavenger hunt for Aita to receive the belated birthday present of her dreams.
Huh???
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This is a fic in the The Lost Changeling series. A slightly earlier installment ended up redeeming Cozy Glow due to a friendship mission.