If you’re wondering about the paradox  
and other science facts (la-la-la),  
Just repeat to yourself, “It’s just a comic,  
I should really just relax…”
 
PONI COMIC THEATER 3000!

@Background Pony #0F5D  
In the words of Queen Elsa:
 
Let it go, let it go!  
It’s just a kid’s show!  
Let it go, let it go!  
No need to get buthurt!  
The bronies need to learn  
To just roll with it!  
Why start a shitstorm?  
The fanworks are better anyway!

@HJSDGCE
 
@Sr Pelusa  
I love seeing discord cry and physically suffer.

@Niggoslav_Krawczyk  
There is a time and place for that.
 
This is only half such one.

@Background Pony #E057  

And now I want to see Evil Luna Before She Was Evil, Evil Luna, Good Luna Before She Was Evil Good, Nightmare Moon, and modern Luna all in one room together.

Oh…at least its better then the way she was portrayed to Cook in the one Fanfic I read

Luna: More pepper?  
Star swirl: just a tad more.  
Luna: dumps crate of pepper marked “a tad more” in the chili  
Star Swirl: Perfect.

@anonymouspegasus  
In that case, let’s share a brohoof.

Does anyone remember the rpg computer games Ultima? And then how it spun off with Ultma Online? How Lord Blackthorne had that magic crystal that shattered and created this multiverse where each contained a different version of Britania?  
I wonder if something like that could work for Equestria and their multiverse?  
For the ponies there could be an ancient type of magic that shaped their world and allowed for all sorts of different magical creatures to exist. But originally that magic existed only in a natural form, something that ponies and other creatures had no control over. As unicorns and pegasus evolved in both technology and started to understand magic, the strongest ones eventually learned how to control magic and learned how to shape pony genetics and started a new breed of pony type the Alicorn.  
But as they started to mess too much with controlling both nature and magic, such as raising the sun and the moon, and controlling the weather. And even learning advanced stuff like time travel. They eventually dug too deeply in how the universe works and actually caused a crack to occur. Which lead to the multiverse.  
Starswirl the Bearded actually knows of this crack. Hence his traveling through mirrors into parallel universes, he was trying to map out all of these cracks to try to fix the universe. But he died before his research was finished. And now his research in traveling through the multiverse exists souly for entertainment purposes, like watching hot princess sisters fighting their evil twins.  
>_>

@PonyPon  
True, that’s also a possibility, but since we haven’t been given any explanation at all on Celestia and Luna’s origin within the show, we can only guess. Since moving the sun and moon was originally the collective responsibility of the unicorns, most assume they were born alicorns and/or had at least one unicorn parent.
 
Hell, with Tirek’s existance and purposely vague explanation of how he was defeated, as well as Sunset Shimmer in EG #1 finding (and throwing at her teacher in rage) THE book on how Celestia and Luna became godly Alicorns, we don’t even know for sure if Celestia and Luna were ANY of the 3 tribes originally.
 
A book called ‘History of Equestria: Who was Megan’ is a pretty curious title of a book to find the key to becoming a godly alicorn. Especially since it was a history book that was made forbidden for anyone to read…

@Background Pony #7236  
Or,  
Luna was a pega before Alicorning, supported.

Alternate-Luna putting less emphasis on the unicorn’s traditions and wearing Pegasi formal wear as princess?
 
….OMG. Lunar Republic Luna is canon.

I hate you Price!

@Sr Pelusa  
Stop posting that everywhere!

@CronoM  
Or since this is the mirror verses
 
That isn’t Luna its nightmare moon

@HJSDGCE  
Its implied that when Evil Celestia returned from banishment, she used her magic and influence as Luna’s big sister to corrupt her.
 
One of Luna’s most prominant issues shown in As the Sweetie Belle Tolls and Sleepless in Ponyville it is psychologically hard for Luna to escape the influence and shadow of her larger-then-life older sister.
 
However, based on Alt!Luna’s comment about any version of Celestia being a pushy older sister  
>>634781  
Evil-Alt!Luna still has some misgivings about how Alt!Celestia controls her life.
 
Our Luna has darkness in her heart but has strong morals and a very, very strong will. One that can bounce back.
 
Alt!Luna is outwardly cheerful and kind but she has a very weak willed and doesn’t have a strong moral center, ergo more easily influenced to become evil by her domineering sister.
 
P.S. On a side note, one REALLY interesting thing is how Alt!Luna decided to re-define herself while her sister was gone. LOOK!
 
Instead of conforming to unicorn Mid-European standards of regal-wear, she wears traditional pegasi Anchient Greece regal wear.
 
I LOVE these little touches :)

@HJSDGCE
 
I can see happening something like this…warning fan-fiction in the comments time
 
“You are getting familiar with your fake sister, Luna?”
 
“Celestia, what I do or my aquaintances shouldn’t be relevant to you”
 
“Oh, excuse me. I was just asking myself how could you be so friendly with somepony that is clearly stealing what should be yours”
 
“What are you talking about?”
 
“I am talking about Sombra, my dear sister. It must be dissapointing, knowing him for centuries, only to see him fall for somepony else, somepony that is not even from this world”
 
“You are talking nonsense sister, I am not interested in Sombra in that way”
 
“You can fool yourself, but you can’t fool me, sister, maybe after he leaves this world then you will you see the error of your ways”
 
“Leave…this world?”
 
“But of course my dear, how else do you think this lovely relationship will end? two Celestias can’t exist on the same dimension for long, so sooner than later dear Sombra is going to elope with his girlfriend, and you will be left alone here, forever”
 
“No…that can’t be…we are friends…we are…”
 
“Don’t cry dear sister…I can help you, I believe I have found the way to separate Sombra and her new friend forever, trapping them in their respective dimensions…but I can’t do it alone, I need your help, and only then, Sombra and you will be together forever”
 
“Together…forever…I don’t want to lose him…I don’t want to be alone…I…him…”
 
“So, what do you say Sister, are you going to help me protect this dimension…or you are going to side with a stranger from another world”
 
”…What do I have to do, Sister?”

@HJSDGCE  
What I got from the comics so far is that by traveling through the mirror numerous times to that specific world, really messed things up for their world.  
I guess its the same as going back in time and messing with your younger self or your parents or something…  
Whats that word..  
Paradox! But I don’t know if paradoxs is the word to use when visiting a parallel universe and messing around with different versions of people you know and then bitch slapping the different you.

@Background Pony #CE37  
I suddenly have a theory.
 
What if she was jealous of Good Celestia and Good Sombra that turned her evil?  
I mean, jealousy was the catalyst of Good Luna turning into Nightmare Moon, so why not this universe as well?

@HJSDGCE  
Maybe Mirror Sombra – with the help of Discord – used brainwashing to turn her into a good pony until Celestia with the help of the evil Mane Six could break the spell and she became evil again.

Wait wait wait… so the Mirror Luna was like Canon Luna before she became evil and joined her sister on the Dark Side?
 
…I feel like Andy Price is now playing with us like that.

But how did Luna turn evil?!  
You don’t turn evil for no apparent reason!  
D:

captain…goodguy? You srs nga? U SRS? That’s more terrible than when Sunbutt stole all those cakes! I thought this series was meant to be written for little kids, not BY
 
@Masem Altworld confirmed for Amestris!
 
@Background Pony #A41A It’s a shame they didn’t go the Sliders route. Would like to see one with the princesses all retired because Blueblood is so competent he can rule both kingdoms at the same time and still has time to show his Shy lady a night on the town.