A story in the same vein as My Little Dashie, but not a carbon copy.
Awoken in the middle of the night by a mythical creature sitting on his doorstep, a man's life is drastically re-arranged by the sudden entrance of Princess Celestia. Struggling to accept things he couldn't ever think possible, he'll have to make a decision about what's worth changing his entire life.
(Note: I added the "Alternate Universe" tag because I imagined this being a reversed-roles universe where Luna is the big sister and banishes Celestia, rather than the other way around.)

No one can make you change but yourself.

Before Nightmare Moon, before Equestria, before the Alicorn sisters moved the Sun and the Moon in the sky, there was Luna.

Luna, and Celestia. Two ponies left alone by a twist of fate that came too soon.

In order to survive, the sisters leaned on each other. They became close, closer than any sisters could ever be.

Closer than any sisters should ever be.

For the April 2019 incest contest
Special thanks to ChudoJogurt for helping me make this story readable.

Cover by Akeahi

Celestia and Luna are a pair of sisters. They have always been known as a pair of sisters, since the time they went to study under Starswirl the Bearded himself. Yet perhaps over a thousand years ago, this wasn't always how things were. Sometimes, you have to keep secrets about the ones you love, even if you wish things could be different.

For the sake of the future, of course.

Entry for the April 2019 Incest is Wincest Contest
Art by Robiin