Plays a key role in-universe: the more politically-minded Celestia prefers living among her subjects as a guiding light. Luna sees this as stifling and fears her sister is abusing her powers as a goddess to forcefully rule over her subjects -- a tyrant suppressing their growth and independence so that she can control them eternally.
In-universe, Luna is starting to realize this might really be the case.
The Author spent way too much effort trying to make Canon Luna fit into his Luna, most told him he was trying too hard.
Captain Braveheart comes off as a Complete Monster for the reasons outlined below. Later chapters have delved into his motivations for this behavior to paint him as a Well-Intentioned Extremist, and insists he is a hero -- at least, in the eyes of his soldiers.
Recently the author had one with the recent Hearth's Warming play, stating that the real history would have played out more like real life European Settlers and Native Americans, ignoring the fact that just would have resulted in Windigos showing up again.
The author's Fluttershy “really, really, really hates dragons”.
Sadly so far the writer decided not to do anything, opting for a rewrite of the notes page explaining the flaws. The sad part being due to a minor *Creator Breakdown (due to backlash about said flaws) it comes off as rather meanspirited and insulting (which of course is leading to more backlash).
The author's notes have since been removed, as it was a violation of one of FanFiction.Net's few rules.
Broken Aesop: The author has stated that two of the major themes of the story are that neither of the Princesses are wholly right or wrong, and that it is the responsibility of an individual to face the consequences of their past actions. It hasn’t really held up terribly well as the story has worn on.
Celestia’s actions have increasingly seemed those of a stereotypical Machiavellian despot, clinging to power through any means necessary. The nobles of her court remain the decadent would-be tyrants they’ve always been. Her fanatically loyal guard’s behavior towards her subjects is less that of a policing body or defensive army, and more that of a hostile occupying force. Her former right-hand man is a murderously insane dragon who was abandoned once his usefulness expired.
During the middle portion of the story as it currently stands, it was revealed that Luna was not the wronged innocent she had initially portrayed herself as. Her plan to leave Equestria was born of her own desire to be free of the responsibility and frustration of governing its inhabitants. The nobles who had backed her merely wanted to seize power and enslave the lower classes, and Luna herself was fully aware of it. Despite casting aspersions upon Celestia for the bloody civil war she fought to retain control, Luna justified her attempt at selling the masses into servitude by predicting that they would eventually win their freedom through violent revolution. While she did briefly seem to regret her past actions and recognize her own role in the missteps of the past, it doesn’t seem to have taken. The reservations about her own beliefs acquired in earlier chapters are tossed aside with ease, accompanied by a mental noting that Celestia’s methods and philosophies have proven themselves useless. Her ancient advisor and confidant Morning Star, introduced as a self-serving manipulator and mastermind of the attempted coup, has been revised as a benevolent reformer whose proposals are recognized as flawless even by those who hear them second-hand and lack any knowledge of the matters involved.
Chapter 8 big time. Most of the chapter is used in order to make Braveheart look like a hero that most of the Royal Guard likes. Equestria losing all of its Sugar Bowl nature. The Government falling apart because Celestia has been gone for less than a day. And Luna didn't even come up with the idea of trying to "save" Celestia; she was just manipulated by the power-hungry nobles and turned into their puppet.
Complete Monster: Captain Braveheart, who truly embodies all of Luna's worst fears about her sister and the system she set up during her absence. He flagrantly abuses every last scrap of power that he has, lording over the 'commoners' and relishing every last bit of pain and suffering he causes. He's less concerned about solving the situation that arises than taking advantage of it to torture and destroy Princess Luna and anyone else he perceives as being in his way, all the while justifying his actions with Blatant Lies and trumped-up charges.
And later, it turns out that while he's always been a blowhard, he's A Father to His Men who just really hates Luna after watching a foal die in his hooves thanks to the panic caused during her escape.
Even his superior, General Hawkeyes, flat out tells him that he's a loose cannon and in need of therapy, but that he's allowed his position because he's the best suited for capturing Luna.
Also everyone sees Luna as one Then again, the Dragon Ajax tells her that her actions only caused a bloody civil war, and she's been acting ever since her return as though she were in the right doesn't help.
Luna was revealed to not even have been involved in anything that occured during the civil war however, and much of her perception as a monster is the result of Celestia's smear campaign.
Despite being the antagonist, Captain Braveheart becomes this in later chapters, as the author has defended his callous behavior in his notes and dedicated Chapter 8 to trying to change the audience's perception of him (it didn't).
The Author "defends" Braveheart by not only calling Braveheart a hypocrite, but also describing him as a bully who insults and picks on others to feel better about himself. It would seem the author doesn't understand that these aren't sympathetic traits.
Braveheart has been given the better part of Chapter 8 as an effort to paint him as less than a total monster, with his squad mates coming to stop him from getting arrested.
Pinkie's only role in the story so far seems to be to provide a main character that doesn't completely hate him.
Chapters 11 and 12 have retconned Braveheart into a wise, merciful, and insightful leader who refrains from the use of excessive force, cares for the well-being of civilians, and respects the rights of the accused. He now also rejects the concept of revenge – the most notable change, as it was his primary motivation.
Chapter 13 is dedicated entirely to Braveheart's glorious battle against the dragon Ajax. The rest of the characters watch from the sidelines, alternating between marveling at his courage and skill, and being wracked with guilt due to the negative feelings they harbor towards him. He wields Celestia's own sword, being one of the few mortals ever to live capable of controlling its power. The Element of Loyalty around Dash's neck glows in reaction to him. The dragon eventually flees, but not before Braveheart has been mortally wounded. As he lies dying, all present gather around to eulogize his greatness and to reflect upon their own evils (which is to say, the things that have been blamed on them throughout the story). The pinnacle of it all comes when Applejack apologizes for wronging him. Despite the author's claim that he didn't intend Braveheart's death to be heroic, it's pretty hard to call it anything but a hero's send-off.
Big Macintosh is clearly the author's favorite canon character, with Chapter 3 effectively being a session of praise and worship for him. It verges on Ho YayPerverse Sexual Lust at points.
Inverted with Celestia, who the author has claimed to be his favorite. She has not been seen (outside of flashbacks) since Chapter 1, leaving no defense for her actions or voice to tell her side of events. Her dragon, who calls out Luna's actions, is quickly pointed out by the author to be murderously insane. It's to the point where every single character who is clearly designated as “good” is opposed to Celestia in most every way. Made worse by the fact that the author's notes made Celestia out to be even more dictatorial than she appears within the text of the story itself.
Evil Versus Douchebag: Braveheart's "court martial" by Prince Blueblood in Chapter 8. The reader has a hard time deciding who to root for.
Braveheart vs Ajax. Ajax mortally wounds him by frying and savagely crushing him, though Braveheart manages to cut holes in his wings and stab him in the chest.
Chapter 4: Angel Bunny repeatedly slaps and pinches Fluttershy. Readers didn't react. When this happened in the show...
Season 2 shows that 95% of the things that really threaten the lands are things that can't be harmed/beaten by blunt force, making the recruiting Aesop about ponies like Braveheart being needed kinda silly.
Idiot Plot: Celestia's historical revision relied on Luna never reading any accounts of her banishment, nobody ever talking about Nightmare Moon again, and Luna never noticing the castle's tapestries and stained glass windows portraying the falsified version of events. It took her a year to figure it out.
Given the author's previous attempts at squaring the fic with canon, it would probably be entertaining to see the rationale used to justify Luna's participation in the Halloween-analogue built around Nightmare Moon.
Informed Ability: The story attempts to give us a darker, more manipulative Celestia though one who wishes to protect Equestria while making Luna someone who tried to fight against her sister's rule but suffered from her own flaws. Unfortunately, this story has gained a great deal of notoriety for claiming to be a lot more even-handed than it actually is. Celestia never gets to speak in her defense; she's absent after the first chapter. Luna's flaws are never presented for the reader, at least not without an immediate argument in her defense. As a result, it started coming across as a bog-standard Tyrant!Celestia story.
On the way to the princesses' old castle, Applejack argues with Dash over her unreasonable loyalty to Luna, eventually deciding that she no longer trusts her judgment enough to continue following her sense of direction. She chooses one of the possible paths before them and leaves Dash behind, eventually finding that she has made the correct choice. As she celebrates, a sudden gust of wind snatches her hat away and deposits it at the entrance to a cave occupied by a giant spider. Somehow, this convinces her that she's been wrong all along, and that her view of Luna has been colored by irrational hatred and mortal hubris.
Dash then catches up with her and defeats the spider, proving to her the need to forgive Luna for ever having doubted her.
In what may be the only sound logic in the entire chapter, seeing Dash make an immediate recovery from the wounds sustained in the fight against the spider causes Applejack to realize that Luna's immortality has indeed been transferred. It doesn't last, however, as she immediately believes this to mean that everything the Princess has told them was truthful, and that she should join her friends in accepting her every word doubtlessly.
Karma Houdini: In-universe, Princess Luna is viewed as one, for despite being 'saved' by the Elements of Harmony, many innocents were killed in the stampedes and riots that occured during the temporary 'eternal night' she tried to lay upon the land. And these innocent victims -- including foals -- were not brought back to life after she was 'rescued'.
Braveheart is shaping up to becoming one, although getting humiliated by Prince Blueblood in Chapter 8 comes the closest to bringing him down a peg.
And as of chapter 13, he finally meets his end after Ajax burns and crushes him. But while he technically pays for his crimes with his life and weeps when he realizes he's going to die without seeing Celestia or the sun again, everypony present seems to have changed their tune about him, so he's still Easily Forgiven.
Moral Event Horizon: Played with in that Luna believes her sister has crossed the line with her lies and manipulations, thinking that she did it all to establish herself as a tyrant. Thanks to Celestia's 'enhanced' legends of Nightmare Moon, meanwhile, the public thinks Luna has crossed it -- if not long ago, then by making her sister vanish after their argument at the Grand Galloping Gala.
Most Writers Are Human: A major problem some fans have with the story is that the writer injects human mindsets and beliefs into a world where there shouldn't be, such as sexism against women despite being a female dominated world.
He also seems to have a hard time understanding the more supernatural elements of the show and Blue And Orange Mortaly. For example Discord is merely just an evil tyrant rather than a god of chaos who did everything For the Lulz and Windigos are missing for his retelling of Equestria's founding.
New Powers as the Plot Demands: In Chapter Ten, a wounded Lt. Nightshade flies more quickly than a healthy Rainbow Dash. This could be seen to double as an unfortunate implication, being an instance of a male character easily upstaging one of the canonical female main characters.
The character whose defining trait is her speed, no less.
Real Women Never Wear Dresses: The only reason why Rarity isn't "a model feminist" (in her own words) is because she runs her own dress making shop, it seems. At least, according to career soldier Storm Cloud. Rarity only seems to agree with her point of view on her profession in order to drive home her overall point: that she chose to become a dressmaker instead of taking her cutie mark's meaning (finding gems) at face value and becoming a miner or something that more precisely fits. She didn't see her destiny as set in stone, but uses her talents to support a career she really enjoys.
Then Fridge Logic kicks in when you remember Rarity didn't get her cutie mark until seeing her outfits in the play, which was hours or even days after finding the gems, thus it really means "makes dresses dazzle like gems".
Ron the Death Eater: Despite the author's claims otherwise, this is one of the earliest and most vicious "Evil Celestia" fics.
Spotlight-Stealing Squad: A pretty decent chunk of the story focuses on Braveheart and his squad. He even more or less becomes the protagonist from the end of chapter 11 to the end of 13, when he's killed off. Hoof, just take a look at how much the fics' trope articles mention him.
The inclusion of the Real Women Never Wear Dresses incident detailed above has led to a somewhat Broken Base among readers. Some feel that transforming the female-heavy world of My Little Pony into a patriarchal society is unnecessary and/or makes very little sense and is filled with unfortunate implications. It doesn't help that the primary antagonist, Captain Braveheart, is a misogynisticJerkass.
Chapter 8 heavily implies that most of the government has fallen apart (Celestia having been missing for roughly one day), with the male-heavy Royal Guard being the one exception. As mentioned above, most of the government is female-run, implying that women can't manage things unless they're overseen by a Dictator.
Of the Canon characters, Big Mac is depicted in the best overall light, shown as being closer to Earth and wiser than his sisters. Twilight also has a potential Love Interest added in, implying her being conflicted about the Luna and Celestia situation isn't enough -- there has to be a male thrown into the mix for her to be Wangsty about as well. (Spike is a no-show.)
Speaking of Twilight conflicted about Luna and Celestia, she pretty much on Luna's side since chapter 2, despite Celestia being like a second mother to her and knowing Celestia better than Luna does, even thinking making Luna immortal again is more important than finding Celestia, only thinking otherwise thanks to said potential Love Interest, reducing the shows lead character into a Satellite Character.
It's gotten so bad that the author has decided to revise the fic to remove the patriarchal sexist connotations. The first step is apparently removing all of Braveheart's sexist language.
Which is leading to more Unfortunate Implications as the writer is also trying to make him into an anti-villain by removing most or his horrible actions: so women (or mares) can be flawed and make poor decisions, but men (or stallions) can't and don't.
All throughout the story, from the author's justification for the actions of the guards to Mac's speech to Applejack regarding Luna, there seems to be a nonstop implication that nobody can or should be held responsible for their actions so long as they're Just Following Orders.
Any responsibility male characters hold is downplayed or blamed upon women.
Braveheart's assault on Sweet Apple Acres is blamed on Applejack being arrested and spilling the beans.
Rarity impersonates Nightmare Moon in order to scare the flighty Lighthoof, who has been assigned to guard her. He then runs throughout the streets screaming that the town in under attack, leading to a riot in which a foal is trampled. Naturally, Rarity is the only one blamed.
Chapter 13 sees Applejack apologize to Braveheart. Remember this is the person who threatened to burn her home with her family inside it.
Seinfeld Is Unfunny: When it started the ideal of this story was rather new and interesting, however over time the Fandom started seeing as Celestia the more sympathetic of the two sisters. Now this is just another "Celestia is evil" stories.
Speaking of which this version of Luna was once praised for being so different then other fandom version, now she's a borderline Scrappy.
Villain Sue: Braveheart, whose abusive behavior wasn't kick-started by the tragic rioting deaths caused by Nightmare Moon's return, merely 'justified' by it. So apparently witnessing a tragedy makes it okay to be a sexist racist who abuses his authority, makes false accusations, and threatens innocents with Cold-Blooded Torture to 'bring them into line'.