Twilight was left pondering Azari's words. What did she mean by lies? How and why will Celestia fall? Twilight's head was filled with questions. She looked at the book again and then at the lock. Suddenly the book was engulfed in purple and green swirls. It transformed into a black and red book with a key attached to it. Twilight felt a strange urge to go to a room in the back of the library as if her instincts were telling her so. When she was inside the room, her consciousness returned. She didn't know why she went inside, she just did. As she looked around the room she realized it looked similar to her castle library, meaning it looked like it was only for 1 or 2 ponies. She sat on a chair and looked at the book again. It was still locked. Her frustration growing, she put the tip of her horn inside the lock and blasted it open. Twilight opened the book and looked at the table of contents. It seemed to be a history book, a lengthy one at that. Twilight flipped to a random page. It was a prophecy. It said,
In 104 years,

Two descendants of evil

Shall uncover a truth

and finish what was started

and claim what's rightfully theirs.

Twilight was confused. That sounded a lot like what that mare said. She flipped to the next page and saw that there was more writing.

Two mares,

One shall lead as queen,

and the other

shall conquer great lands.

Two times of day,

created from a shadow,

Shall connect,

and soon, shall set the sun. Next to it was a drawing. When Twilight saw it, her eyes were wide with horror and shock. Depicted in the drawing, were her and Starlight. "No, this, this isn't true. I know my parents. I never had a sister. It's somepony else," Twilight covered her mouth to keep from screaming. It said that two times of day would take over. Perhaps it had to do with Sunset Shimmer. Twilight turned the page. More writing. This time, it was more like a journal entry.

They have come, to try and strip me of my kingdom, as if they can do that. Fools. I am all powerful. I shall not be destroyed by two pitiful alicorns. My empire will not fall. It is rightfully mine and they dare challenge me for it? They are the ones who shall fall.

Twilight concluded that it was something Sombra wrote before he was defeated for the first time. On the next page, there was a second entry.

We have defeated Sombra but I fear the curse he placed on the Empire will have catastrophic results. It said that he would have two descendants who would carry on his legacy. I looked into the future and I know who they are. When they are born, I will watch over one and make sure they don't know. With their magical abilities, they will become powerful unicorns and hopefully use their power for good. Twilight felt angry. It really was her. Why didn't anypony tell her? At least her parents could have told her she had a sister. Her horn lit up. Purple and green swirls flew from it. She walked through the library inside there was a passage decorated with tapestries. She walked in.

They say she has a heart of crystal,
That she has never done any wrong,
That she’s the one behind the greatness of our land.
Tales are told of her victories and how she vanquished foes.
But not once have the mentioned, all her wrongs and all her lies!
Never once have they mentioned, the true hero of them all!
For they say she has a heart of crystal,
But crystals are simply stones! With every word, her voice grew louder. Metal armor formed on her hooves.
Everypony says she is loyal, kind, and just.
But tell me what is just,
About trying to destroy somepony who you’ve never even met!
About lying to somepony,
About her family, past, and destiny!
She claims to be a keeper of peace,
But peace according to who may I ask.
Herself?
Down with Celestia,
Down with her unrightful reign!
She says she’ll rule forever,
But times change.
A new rule must arise!
Down with Celestia!
Her hair turned a deep black. She walked up to a tapestry showing the princess of the sun herself. Her horn aglow, she set a spark to the bottom of the tapestry.
bring peace and more,
forevermore,
if down with Celestia!
she says she is brave!
she is not,
for she is not well behaved!
down with Celestia,
the lies told to us!
harmony will be,
only without Celestia! She closed her eyes. When she opened them, they were red and green, with purple smoke flying off of them, gazing as the tapestry burned.

Author's Notes:

I know this chapter has like, no dialogue but it is an explanation chapter. As for the song, I wrote it, except for the ending which was written by my friend who shall not be named.