In the wake of the interrupted wedding of Princess Cadence and Shining Armor, the Royal Guard went on a changeling hunt, fanning out throughout Equestria to find any changelings living amongst ponykind. The captured changelings have been confined to a guard barracks in Canterlot.
Meanwhile Princess Celestia is finding herself swamped with petitions from ponies across Equestria asking for amnesty for their changeling friends, colleagues, and lovers. Princess Luna, who has been itching to regain some responsibility since her return, offers to take on the petitioners... and the changelings.
(sex tag for off-screen births and hinted baby-making)