So in the Power Pony episode it is established that Mane-iac seeks to destroy Maretropolis. I was wondering if the comic(s) established her reason for wanting to do so?

If not, then what are your theories?

6330034
Well considering her inspiration/she is a parody of comic-book villains who have no clear motivation for doing evil other than just because, and she shares many similarities with the Joker, I would say her intended motivation by the writers is: "She's crazy and evil, so she wants to destroy things because it is fun to cause chaos and destruction".

To throw out some slightly deeper ideas though, I would wager she could be crazy enough to either see herself as, like the Joker himself, "throwing off the mask" of sanity and "freeing" others from the trappings of society and morality. She also could be both crazy and delusionally vengeful, taking out her accident and the pain it caused her on everyone and everything she can.

6331332 Indeed, however we should also keep in mind that while she is inspired by villains such as the joker, that doesn't mean necessarily that she is 100% like the joker. She could also be a lot like Dr. Octopus, who was under the influence of his own tentacles (which to some extent almost mirrors Dr. Jekyll and Mr. Hyde) in most of his stories, after all her mane is fairly similar.

Personally when it comes to villains I prefer most of my villains to have a good reason for doing their lawless deeds. When I was younger I loved the Myst series, however the one thing that bothered me about it was that 90% of the time (if you include the books) the villains were bad guys because they were insane and that was the excuse given for them being the bad guys.

Keep in mind that I'm not saying your wrong. Like I said at the beginning I agree that Mane-iac's motives could very well be like that of the joker.

Out of curiosity what do you think of Mane-iac being a Dr. Jekyll/Mr. Hyde like character? Like a part of her is just like any regular pony and can be reasoned with, while there is the Mane-iac aspect that seeks only to sow chaos and despair. That these two aspects are continually at war with one another.

6331859
I don't know, it is possible, as to my personal feelings... I think it would certainly add a Two-Face-like duality to her that, thanks to her much zanier personality, would be... interesting, to say the least.

6330034
I thought it established that she wanted to rob the city. Then again it's been awhile since I've sat down and listened to the whole episode.

I need to do that one of these days.

Personal head cannon is that she's a adrenaline junkie thanks to her accident, and she gets a thrill out of flouting the law, but that's just me.