Hello my fellow friends. Tonight, I have a very interesting theory about Princess Luna.

Is Nightmare Moon a sister to both Luna and Celestia?

Think about. We can understand that Nightmare Moon is the inner-ego of Princess Luna. She was created out of all the jealousy that Luna had on Celestia. If we look closely at how both Luna and Nightmare look, they look almost same. Sure. I understand that both of them share different looks. The fur, the eyes, tiny bit of the mane, and a little change for both cutie marks, but in end, they could be sisters.

Luna: the light sister

Nightmare Moon: the dark sister.

They should be biologically related to one another. Since we know she is part of Luna, that's bound to make them sisters to one another.

So, is Nightmare Moon considered to be part of the family tree of royalty? Tell me what you guys think about this theory. I'm up for a good conversation.

4714949 Hmm. An interesting idea, indeed.

I'm not sure they could be biologically related, as Nightmare Moon is the physical manifestation of Luna's anger and jealousy. Correct me if I'm wrong, but the show doesn't give a how for why this occurred. If anything, I think Nightmare Moon is a construct bred out of dark magic, fueled by dark feelings of neglect and hurt.

That's not to say that they aren't metaphysically related. As we've seen in recent episodes, Luna has created dream "demons" to help her "punish" herself (i.e., the Tantabus). This leads me to believe that Nightmare Moon is another "demon;" only, much stronger than any other creature or thing Luna ever created. This is possibly because it/she was bred of powerful, negative emotions.

Since emotions are linked to the individual, this leads me to conclude that Nightmare Moon is linked to Luna on a subconscious level. Perhaps she represents or is a construct of Luna's fears and pains, brought to life by powerful dark magic.

Either way, I wouldn't call them "biological sisters," but I do think there is a connection somewhere between them; other than sharing the same host.

4714949 If that's the case, Nightmare actually has a domain. If Luna controls the Moon and the Stars, the Nightmare rules the darkness between them.

I don't see it. They are physically the same being so the closest thing I can think of would be dissociative identity disorder.

4714971

That's the thing. We understand that both of them are different. I understand that Nightmare would be labeled as a 'demon' since she is the one pony that really did a lot of torment against Luna. There's the other thing. Did Nightmare not want to hurt Luna from the start of it all? Was Nightmare unable to control herself to where she ended up putting more pain toward Luna? If there is a connection to both of them, it could mean that they are both sisters.

4714981

True. Let's look at Stars Wars, for example. There are two sides that a person can choose. The light side and the dark side of the Force. Luna was getting closer to the dark side which ended up creating Nightmare Moon. Which, if I'm right, they're both sisters. Luna is part of the light side while Nightmare is part of the dark side of the force. Sisters of opposite sides.

And I agree on what you said.

Luna is I control of the Moon and stars, while Nightmare is in control of the darkness.

4715018

I'm not sure about the identity disorder. Nightmare Moon still looks a lot like Luna. You have to look at the face structure of both Luna and Nightmare. Their faces look similar to one another. But, was Nightmare Moon Luna's conscious? Nightmare was probably wanting to be unleashed from Luna to fight against Celestia. Which would be her being protective over Luna. An angel of darkness that protects the angel of light.

4715061 i'm still not quite getting when you say sisters. Are you saying that Luna and Nightmare Moon have separate bodies? My head canon is Sombra used dark magic to induce Dissociative Identity Disorder (multiple personalities) within Luna. Nightmare Moon wanted to separate herself from Luna so she used magic to change her appearance when she managed to take over Lunas body. Celestia wasn't quite sure what was going on and thought it was still Luna, however the elements of harmony revealed what was going on. This puts Luna's banishment in a different light. The moon is less of a prison and more of an asylum.

I believe that the Nightmare is basically a magical parasitic entity, who took command over Luna by using her weakness (insecurity, jealousy etc)
and eventually strted growing within Luna, later reaching a point where it could physically manifest itself by partially absrbing Lunas
physical form and change it into Nightmare Moon.

Which ALSO explains how, in one of the comic arcs, the Nightmare entity was able to return and this time take Rarity instead,
and turn her into Nightmare Rarity (or as I call her, "Nightmarity").

So I would NOT say Luna and Nightmare are sisters, rather that Luna was the victim of a symbiotic parasite that gradually took over
both her mind and body.

4715391 2 things:

1- Comics are not canon to the show.

2- "It's not Luna's fault! She was possessed!" Yes, let's just ruin any sort of agency Luna had in choosing to kill Celestia, because why not. It'd be too mean and evil if Luna became Nightmare Moon all on her own, can't have that.

4715391
The show canon pretty much contradicts the comics canon on this. There is heavy implication from the show canon that NMM is a part of Luna, rather than an external entity possessing her.