I don't mean the name as we all know now it's Starlight Glimmer (Really? Come on Hasbro), but name aside we know next to nothing about her. So let's analyze what we do know.

Besides all the communist talk about her (Actually resulting in her fan name [a better/smarter choice]) we know she runs a town found on a map in Twilight's Castle where everypony has an equal sign replacing their cutie mark. We know this from the various trailers in which all the town's ponies have equal sign CMs, also we can take an educated guess it's some kind of spell cast by her or somepony she works with. This is shown by some of the mane six's marks also getting changed (and also because it's hard to believe an entire town has the destiny to be equal with everypony) and we can guess it's a spell based on the faces of the affected ponies.

Let's be honest, you all probably already knew that. So let's talk about why. Why would she do this? How could she do this? Why didn't Celestia do anything?

My theory is this
As a filly she must have had a rough time finding her special talent only to either not find it or feel it's lacking compared to her friends. Let's be honest which would you take Applebucking Farmer or Magically Talented Alicorn Royalty as your destiny? If this is the case it tackles a huge issue which will spark a lot of controversy. It tackles fairness of life. If you had to wear a brand saying "next in line to run the farm" and your friend got "Royalty" I can have an idea your saltiness level would be higher than McDonalds fries, unless your Applejack.

So she figures out her destiny and was unhappy for some reason, so she decided to defy it and instead create a world of equality. Now that seems drastic even for the cast of villains on the show. "I'm unhappy with my future, time to change everypony's," yeah maybe a little drastic. So why would she? For the most part everypony is happy with their destiny they get on their cutie marks, so why would she? She wouldn't at first. Like all ponies she would be happy to earn it and show it off, until... Somepony get's a similar, but better mark. In this world not all ponies are equal (true to reality, no one is the same) however in this world your fate is decided at a relatively young age and you can't change it. For most it's not a problem not to mention their culture is made so that they don't care about the differences much or that they have a relatively assigned place in life. But let's say she was a grape farmer, she's happy doing this until some other pony comes along and is just a better farmer in general. It wouldn't bother her at first besides being a little jealous like a normal human would be, but in pony society where your cutie mark can define your place in life and somepony gets a better one that's really close to yours, again Micky D's level of saltiness. But still even that wouldn't drive any sane being off the edge, unless it was a friend. Imagine your best friend get's your special talent (cool) but is just born to be better in a world where your talent defines who you are (not so cool now).

Driven over the edge by her friends involuntary betrayal (She didn't choose her destiny), by seeing her close friend be better at the thing that defines her as her. Get a job? Too bad she's second best. Something else? Nope her destiny is permanently branded on her backside.

Like a bad RP your opponent is always going to be better because reasons. Unless everypony is equal. If everypony was the same, nopony would be better or worse. You could do anything because you have no set destiny. There's no winners or losers only ties. With this world she would no longer have to deal with second best or worse. So she sought out the means for her perfect world.

But hey, that's just a theory. A pony theory!

Oh my God, I just realized the similarity between the names Starlight Glimmer and Twilight Sparkle.

Really? This is just as bad as Sunset Shimmer!

By having such a similar name, and the fact that she runs a small town like Twilight does, could this be a possible indication that her character and life might be a parallel to Twilight's?

Anyway, interesting theory. I wouldn't be surprised if you're right.

4141341 Thank you, thank you. Turns out watching about three hours of game theory can help you.