Save me from this madness

Wait whaaaaaaaaa?

Twilight reread the journals six times each to try and understand, she still had so many questions.
Slowly she began to piece together what was explained and she muttered to herself,

"So there was a Queen who made other princesses and princes in case anything happened and then she had the firstborn Alicorn...then there was a war between the Queen and Queen Chrysalis...and now we have to find them?"

Applejack who had finished making all the crystal empire food early came by and spoke aloud.
"How do we even know if tha Princess an' Queen are alive?"

Fluttershy whimpered as she spoke, arranging the white Roses with lavender.
"They could be hurt or worse..."

None of them could mention what horrible things could have happened but the silent thought of why wouldn't they have returned by now lingered in the air, the whole idea causing Twilight to groan. If it weren't for the gala she wouldn't feel so pressured to hold herself back from finding the answers she so desperately wanted.

Cadence, however, was more than pleased to relieve her of her thoughts, mentioning the scavenger hunt.
"Clues have been placed all around the castle, your friends can help too!"

Of course, Celestia had already been informed about the hunt and what the actual 'prize' was, the reveal of Cadence being pregnant. So while the main 6 ran around trying to find the clues Celestia pulled Luna into a private audience, wanting to speak.

"Luna, do you think that you have the power to restore the scroll? It may say the things we already know but it could hold the secrets to where Princess Nova is."
"Thyself dear sister? Why would thy have the power to restore the scroll?"

Celestia hesitated before taking in a deep breath,

"You are the Princess of the Night, you have embraced dark magic before and should the scroll be protected by dark magic you could-"
"No"
"But Luna-"
"Celestia. I cannot risk becoming corrupted once more, even if the reason is of higher importance becoming Nightmare Moon again would be worse than death."

Neither of them said another word, hearing the squeal of Pinkie, assuming that news of Cadence's pregnancy.
The thought of Luna embracing dark magic once more for a simple spell wouldn't stray from Celestia's mind, she understood her sister's contempt against it but it was as Starswirl had said, they needed to find Princess Nova and Queen North.

Twilight seemed thrilled at the news of her niece or nephew, her laughter only halting when seeing the concerned and rather distant expressions of the Princesses.

"Princess Celestia? Is everything okay?"
"I think I know what we can do to get the scroll restored and unshielded."

Celestia could feel her sister's scornful glare but carried on,

"So far Cadence has tried using her spells to take down the shield and restore the scroll, but all have rebounded therefor I assume we are dealing with a dark spell. To take down a dark spell one must use dark power, such as Luna."

All eyes landed on the Princess of the Night who raised her wings, trying to steel herself at that moment.
"Yes, however, I have already decided not to tempt my fates with the corruption of dark power."

Rainbow Dash held up her hooves and pointed at all of the ponies.

"Can't anypony use dark power? Why not find a unicorn who does dark spells and ask them?"

Celestia shook her head, lighting up her horn with a gentle sunny glow. Showing all of them a vision of anypony who uses dark magic, beginning with Luna.

"There are unicorns born into the darkness such as Luna who are naturally gifted with dark qualities however for an average unicorn to practice dark power is extremely rare. We are born into the light, our power is created from it."
A pause filled the air before she continued,
"We use the light and love of harmony to live and are naturally tied to that so for anypony to attempt dark power it is unnatural and can lead to corruption."

The vision of Luna changed as she turned into Nightmare Moon, the actual Princess Luna turning away from the sight with her ears flattened. Only for it to change to a young colt, with a shadowy colt and hair as dark as coal.

Rarity tilted her head asking who it was, Celestia almost lifting the corner of her lip.
"Sombra, before he was corrupted."

All of the mares besides Luna and Cadence gasped, watching as the young colt played with dark power. Listening as Celestia explained,

"Whenever somepony leans into the power of darkness it is almost impossible to break free of, depending on the amount of use and the pony using it the corruption can spread to the mind and slowly tempt them to continue until it takes full control. It is a parasite that feeds on the light of your soul until there's nothing left, once you touch dark power it will never quit trying to persuade you. Luna only managed to hold it back for so long due to being born to wield the darkness of the night but not the darkness of the void."

They all understood now, why Princess Luna hesitated and why there were no unicorns of dark power in Equestria.

This complicated things...