Dear Princess Celestia,
In my recent studies, I have found more about the Nightmare that had taken control of your sister, and my adopted sister, Princess Luna. It wasn’t an easy feat, but I had been able to do it, with some wonderful test subjects.
What I have learned, is that the Nightmare wasn’t just something that Luna had. It’s in everypony.
The ‘Nightmare’ is made of Jealousy. When the Jealousy grows, the Nightmare grow with, until it can take control. It is also made of Hatred. It’s about a 66:33 ratio of Jealousy to Hatred.
When Princess Luna was overtaken by the Nightmare, she was extremely jealous of the power that you had. As I know, and what she has told me, ponies loved you, and barely even knew of Luna. The Day Court would be filled with ponies, while the Night Court was only accompanied by the Guard of Luna.
As the Jealousy grew within her, the Nightmare grew as well, until you confronted her at the Castle. It had finally grown enough to get the power to overtake her, and turn her into the feared Nightmare Moon that everypony knows of.
What I have also learned, is that the Nightmare rests in everypony. I went around to Ponyville, Canterlot, Las Pegasus, Trottingham, and Fillydelphia. Every city that I went to, I gathered up 60 ponies, and examined them. A Nightmare-like substance, the same thing I felt when we tore the Nightmare from Luna, was resting in these ponies.
Jealousy is a normal emotion that is emitted when somepony is envious of something that another pony has, that they do not have. In Luna, this was very big with your fame and power. She wanted to have it as well, but she never did. The Nightmare grew.
I have also found that the older a pony is, the more of the Nightmare that resides in that pony’s body. With their older age, they have had more time to build up a Jealousy towards a pony, or multiple ponies.
With that being said, it also makes sense that Alicorns would be more susceptible to the Nightmare. If they are ‘infected’ with the Nightmare, and it is beaten by the Elements of Harmony, or another Force, it resides back to what it originally was when they are born.
From what I have read, your Mother and Father were taken over by the Nightmare, but neither you or Luna knew until it was too late. The Nightmare had taken over their bodies past the point of fixing. What I have read, you and Luna were forced to kill your own parents, and for that, I am deeply sorry for your loss.
I also went to the Crystal Empire to speak with Princess Cadance. I examined her as well, and the Nightmare was larger in her, because she was an Alicorn. Even though Alicorns are not as susceptible to normal things that Earth Ponies, Pegasus Ponies, or even Unicorn Ponies can be infected with, the Nightmare is more prominent in the Alicorn race.
As Alicorns rule over a certain place, they see ponies all the time. Most ponies believe that Alicorns have everything they ever wanted, but that is not true. Many times, Alicorns are jealous of the normal pony life, with no bother of extreme politics. With that being said, the Nightmare resides more in the Alicorns, like I have said before.
Even with this being said, it is easier for the Nightmare to take over a normal pony’s body. They do not have the forces blocked up as fiercely as the Alicorns do, making them more susceptible to the Nightmare, or any illness, in fact. With that being said as well, Alicorns need a higher build of the Nightmare for it to overtake them.
From my studies, the Nightmare is a force created by the First Alicorns to inhabit the Earth. They made it to strike fear into their subjects. However, it backfired, and also encased itself into the Alicorns. No matter what they tried, they could not get rid of the horrible Force they had created. Over the many years, ponies became infected with it more and more. It would often kill them, for it’s strength that it had for being so new.
Just as filly Unicorns have surges of magic, because they have not learned to control it, the Nightmare did not know how to control itself. It would overtake ponies in a heartbeat, and kill them the next minute by mistake.
The Nightmare isn’t just a substance, it is a living creature, that will fight back. Even though it is living, it cannot live in it’s own body. You cannot remove the Nightmare from ponies. Even if you could, it would die instantly, as well as kill the pony it inhabited.
The Nightmare is a parasite, living off the Jealousy and Hatred of the pony that it inhabits. After the years, it has learned how to control itself to only feed off Jealousy and Hatred, thus making it grow quicker, since it is a dark force. When it began, it fed off all the emotions, and that is why it overtook ponies so quickly.
Ponies have also built up a resistance to the Nightmares power. This makes it harder for the Nightmare to overtake the ponies, but it still can. Alicorns haven’t changed their resistancy, for it already being very high.
Even though the resistance to this getting higher, that doesn’t mean that it still can’t overtake a pony.
As I saw the Nightmare being torn from Luna’s body, and how sorry she was for doing what she did, I knew that there was something more to the Nightmare than what we all thought. When I was in the flashback of you banishing your sister to the moon - I’ll explain when we see each other - I saw that Luna looked a little scared of being overtaken like that. I imagine that you saw her face, since it was obvious that she wasn’t talking to me, but she was talking to you. When she transformed into Nightmare Moon, it was like a whole new pony.
Even though I haven’t studied possession much, from what I do know, it turns you into somepony you aren’t.
Judging by the extensive research I have done, I can conclude that the “Nightmare” exists in everypony, but we just can’t see it, until we open our eyes.
Sincerely,
Princess Twilight Sparkle of Equestria, Co-Ruler of Equestria, and The Star Princess