Long ago the universe was ruled by Chaos. The power he wielded corrupted him, and Order was too peaceful to fight back. Order had a daughter, Gaia, and Chaos had a son, Cronos. The two fell in love and created Equestria. During the reign they had two daughters, Luna and Celestia.

This is the story of what happened when Celestia and Luna were left to save Equestria from the true eternal darkness.

Note: Cover art is not my own. I got it here: http://browse.deviantart.com/?q=filly%20Luna%20and%20Celestia&order=9&offset=24#/d46t5rl