This story is a sequel to New Friends Between Realities

The Explorers Guild. Ponies charged by Princess Celestia and Princess Luna to explore the wild and unchartered corners of Equus.

So when an uncharted and deserted island far to the south is uncovered, the Guild jumps at the chance to see what no other has seen before.

A thousand years later, what they find there will change the lives of two in ways neither had ever expected.