Changelings and ponies had always been natural enemies of each other, especially with the crystal ponies when they were around. Why wouldn't they be? Changelings were like parasites, feeding off the love that ponies gave off and driving them to illness.

However, Changelings had begun to decline. What started out with as seven hives have diminished down into three, all of which had gone into hiding so well that most ponies didn't know what changelings even were. Even Celestia had not seen one for quite a while, a long feat for an immortal pony.

Until she found a nymph. A new Changeling Queen.

Unable to find it within herself to abandon the changeling, Celestia ends up taking the nymph back to Canterlot under guise as Twilight Sparkle. The plan was simple; find the hive that Twilight belonged to and return her back to be raised with her race.

Of course, despite everything she learned through her long life, she had forgotten that things were never that simple.

For starters, she did not anticipate herself to grow fond of Twilight as time began to pass, or to beam in happiness when Twilight began to refer to her as mom.

Many Many Thanks to my Pre-Readers: Rewrite and Doctor Disco (Welcome to the Team Doctor!)