Pony POV Series/Analysis

Despite coming from humble origins as an attempt at humanizing the Mane Cast's fall to discording, the series has become increasingly deep and interesting, particularly in the second story of reharmonizing.

the reharmonized series and the importance of facing reality
Note: Spoiler ALERT for all those not wanting spoilers for the Reharmonized Series!

In the Reharmonized POV Pony series, the importance of facing reality and its complexities really comes into play as a theme of the series. The author uses all the mane cast for this work, and each of them eventually have to face reality in their own way to be the better ponies.
 * Rarity had to face the reality of her Greed, and gain insights about the nature of Generosity. Broken by her inner faults, she initially lashed out at any gem, angry at their natural beauty betraying the beauty of relationships. Yet she eventually began to realize that they could still be useful tools in her line of work, and that to be generous to those who deserve it least is also for those who might need it most. This was accomplished in three ways. First, Rarity reconciled with The Diamond Dogs, allowing them to have some gems as she knew they had an appreciation for beauty as well. Second, Rarity realized that giving time is being generous as well, and finally, that the most precious things we already have: Family and Friends. From that, she chose to be generous not only with old antagonists, but even with those whom others would shun away, realizing freedom in her heart.
 * Applejack had to face the Awful Truth about Life. Those other ponies? They had UNIQUE problems. People will die. That family and friends are fleeting in this world, and that even in places you told yourself you'd be miserable, there can be joy. By facing this reality, Applejack is devastated at first, but afterward, she uses every fiber of her being to make certain that people's REAL problems are at least addressed. It also gives her a unique look into the reality of their world, and become a sort of secret keeper for Luna and Celestia as a Living Lie Detector given unique knowledge about how their world is changing.
 * Pinkie Pie tried to categorize herself as only happy, when she knew that there was sadness in the world as well. She fought this idea through denial for 3 weeks with no sleep, until her Battle in The Center of The Mind forced her to accept that laughter can be cruel, and that unless she learns to accept all parts and emotions of life, she'd never be a true element of harmony. After accepting this reality, Pinkie Pie suddenly becomes Wise Beyond Her Years, and uses this and all her knowledge of reality (including Medium Awareness) to help others through love and joy.
 * Rainbow Dash tried to run away from the reality of loyalty to one thing might mean betrayal of another. She tried to bury her guilt and think of her friends as Invincible Hero team. It almost sent her into shadows. Yet it's only when shown the impossibility of not choosing something that Rainbow was able to make peace with herself, and show that since she cares about so many things, she is indeed still an element of loyalty. With this reality, she chooses to reward her loyal fan Scootaloo by helping her with her Real problems, and becomes all the more free for it.
 * Trixie tried to hide in her talents and loneliness rather than deal with the reality of her life. It took several long talks with Twilight Sparkle before she was reborn, grew into a better pony by learning all about friendship, trust and individuality within a group. And before long, she could declare  The final acknowledgment of her new reality as something better.
 * Luna was forced to be the Only Sane Man when Discord ruined Equestria, even discording Celestia, and so was witness to all the absurdities of his reign. She even contemplated returning to be Nightmare Moon to try to stop him. Yet after seeing how Celestia treated her former conspirators with mercy, she realized that she had to take responsibility for her actions as Nightmare Moon as she was mostly responsible for them, and chose to feign madness while she found the one thing that could save the world: Twilight's friendship letters. She sent each of them and saved the world. Afterward, she sought to allow the reality of her actions be accepted and forgiven, while assisting her sister and conversing on how they wanted to change Equestria.
 * Luna also wanted  Note: all this is technically optional canon, but still hinted at in the main stories.
 * Twilight Sparkle had her Darkest Hour when her friends abandoned her against Discord, and thus thought she wouldn't need to deal with her element being compromised after the fact. (Her element being the Magic of Friendship) While Lesson Zero showed that she still needed some therapy to help with her compulsion for order, her real challenge was on deciding whether other ponies could learn about friendship. But it was more than that.  This lead up to her greatest challenges in being confronted with the problems of Trixie and Fluttershy. Somehow, simple magic couldn't overcome Trixie's problems, and Twilight felt responsible to help trixie through her problems. In her work helping Trixie's Case study, Twilight got to understand the importance of Friendship by seeing a pony like herself. It also lead to a surprise  . In taking on the role of teacher, she grows more free in beginning to grow.
 * Fluttershy, OH MAN! Fluttershy had perhaps the most dramatic re-harmonizing of all. Originally just challenged by her Shadow self Fluttercruel, she sang that being into submission as a Badass Pacifist, slowly teaching "Cruel" the ways of caring and kindness. Fluttershy even allowed Fluttercruel to come to the surface when more certainty and force was needed. Yet it was when Fluttercruel had her rebellion of mind that the great trouble arose.
 * Fluttercruel, her shadow self skulked in darkness, seeking to get out and make Fluttershy cruel. Once it happened though, Fluttercruel was confronted by the reality that no matter what, she'd always start as Fluttershy's copy. Trying to teach fluttershy about reality almost sent "cruel" to oblivion without truly teaching Fluttershy what needed to be learned. Yet as The Determinator,
 * Similarly, all the side characters had to confront their fears and sorrow in reality, and while some continued to grow from it, others, well, others still have a ways to go.
 * Spike
 * Spike needed to realize that if he really wanted to be noticed, he had to conscious in his actions with others, and be willing to be more than just a friend of a friend. From this he becomes the fourth crusader with the cutie mark crusaders, and a mature voice of knowledge and reason within the group.
 * Silver Spoon
 * Having you opinion about world around you is really damn hard. Fighting for a right to have it is firstly is fighting with yourself and only then with those who boss you around. I think Silver Spoon went a lo-o-ong way and she will have to go even longer but i'm sure she will be able to do it on her own.
 * Also, family is super wonderful. After an important talk with the crusaders, Spoon finally realizes how important her family is to her, reconsiles with her father, and becomes a much happier and healthier filly for it.
 * Celestia
 * Zecora
 * Diamond Tiara
 * Onyx Tiara
 * Onyx Tiara

On the nature of the Elements of Harmony
According to the series, each of the Elements have at least four "states". 1. The normal one, where it's recently awakened or not stressed. This is what the cast have for most of the first series in general, where it's a main trait of their personality.

2. The "reversed" one, as in their discorded selves. The opposite of the trait is as fundamental to them as the original used to be.

3. The overloaded one, where their personality has focused on the element to the exclusion of almost all else. This comes up a lot in the POV series, from Pinkie running away from her problems by engulfing herself in a constant party, to Nightmare Whisper, and so on. This is generally what leads to a "Nightmaring" state, and may be accompanied by the belief or realization that the element is self-contradictory, at least at some level. Officially, we've seen AJ's, Dash's and Pinkie's versions in AJ's recent Vision Quest, and Shy's version in reality. Rarity... probably would see possessing things as wrong and evil, and Twilight or Trixie going Nightmare may involve over-boosting magic to the point of national devastation, or alternately an overwhelming obsession for friends regardless of the consequences. The question then is, does pride count as a virtue under certain circumstances, and was that what made Luna go Nightmare?

4. The fourth state, one that only Pinkie, AJ and the Flutters have at least partially reached with certainty (there's still an element of uncertainty with the rest of the mane cast). This is a sort of apotheosis, where the element and its' counter-trait are balanced, and an internal harmony and peace is reached. Dash is close, but she hasn't really conquered the overloaded version of herself yet.

Nightmares and Alicorns

 * If Nightmares represent a mono-directional force, then Alicorns represent a duality or spectrum.
 * "An Alicorn is a part of everything." This duality is the part that exists in everything, regardless of being in the positive or negative form. For Pinkie, she can represent either the joy of laughter or the frustration of anger, which are both feelings, therefore she is likely the Alicorn of Emotion.
 * Nightmares are formed from a single part of the spectrum, in theory, it can be any part, as Word of God mentions RD as either Nightmare Manacle or Nightmare Victory, but in practice, it will always result in the strongest part seizing full control.
 * For this reason, a Nightmare is much stronger than an equivalent Alicorn, as demonstrated when Luna in AJ's Dreams believes she would have been overpowered and prevented from sending a distress signal in mere seconds by Nightmare Mirror.
 * In exchange, Nightmares have much less freedom/discretion, acting more like a force of nature than a character, in addition, at least four of the Mane Six Nightmares have the MO of stripping away free will by geass.
 * Nightmares are not necessarily evil or even bad. To state they are, just because of their focus, is the Golden Mean Fallacy in action.
 * On the other hand, there's no way to tell for certain if Nightmares are right in raising one virtue above all others, as such a position has been criticized before.
 * None of the Nightmares have interacted with each other yet, but the ones with mutually exclusive objectives would probably be hostile, eg The Kindest of Lies vs. The Cruelest of Truths.

The Element of Trust

 * When talking to Trixie in Second Family, after the others listed off their elements as being important, Twilight mentioned "Trust". And despite how it's not an Element, it's still an important personality trait, which has a normal, reverse, overpowered and apotheosis state like the others.

Normal is obvious, a trusting person. Reverse is someone who refuses to believe anything others say. Overloaded is when a person gives of their heart instantly to anyone, and enacts terrible vengeance on anyone who is even perceived of as betraying them. And Apotheosis is when the person can evaluate the trustworthiness of others, and trust them in return.

I think that's probably the central character trait of Princess Celestia. (Witness her reaction when Twilight messed up! Good thing she wasn't in the overload state mentioned, or Twi would probably be an integral part of Iapetus or something.) This also explains why Nightmare Moon got as far as she did - Celestia's trust was used against her.
 * This analysis is read by the author clearly. Apparently, the elements of harmony were originally 7 elements, but discord crushed the element of trust into powder, forcing the sisters to cheat. Yet the element still exists, just not in physical form.

Nightmares and their part in the series

 * The suite of Nightmare forms we see really fit well with how a deranged obsessive would try to bring them about.
 * Rainbow Dash's Super Powered Evil Side: Nightmare Manacle attempts to induce a situation that maximizes loyalty beyond all comparison. However, the nightmare actually renders it meaningless - in a hive mind, there's no such thing as loyalty because there's no such thing as the individual, and loyalty becomes self interest. Similar to how Kindness has no real meaning with no choice in the matter.
 * Pinkie's nightmare, Nightmare Grandfalloon is hopefully averted by her apotheosis, but we see it nevertheless - and it again matches the pattern. The nightmare exists to create a constant state of laughter (like the joker?), but this removes the meaning of it. Laughter's joy is that it's fleeting, and laughing no matter the situation is dishonest and unnatural.
 * And as for AJ's side: "Nightmare Mirror" is the most appropriate name, yes. It shows the bare truth, and nothing more. But as AJ pointed out, the cruelest of truths aren't the whole story. While truth is not something that becomes a lie on over saturation, it becomes... well, there was a Discworld story where Death pointed out how there is no such thing as an atom of mercy, a molecule of truth, a nucleon of justice. But they still exist. They're emergent properties. And laying bare every single fact about someone doesn't add up to the whole, as they're not weighted.
 * Fluttershy meanwhile actually became Nightmare Whisper as a reaction to the cruelty inherent in nature. She tries to remedy this by not offering more kindness to those who need it, but instead by forcing on everything, whether they asked for it or not. In sort of a strange inversion of Nightmare Mirror, Nightmare Whisper represents a world where cruel truths are hidden behind comforting lies and illusions so that no pony will have to deal with them. On the downside, no pony would ever have need to become something greater than themselves. Fluttershy overcomes this by accepting certain truths about kindness.

Alicorns
Alicorns have shown up in three different ways in the series. The first is in the Loose Canon side story with Pinkie, wherein they are the "creation" aspect of the multiverse, and opposite to the Draconequui. The second are the group of whom Celestia and Luna are a part, who appear to be based off the Tarot. Only two of them survive at the moment. The third are the formerly mortal ponies who have undergone what could be called alicornization, whether by way of Nightmaring or some other, unspecified process. Most of the Alicorns that show up are Nightmares (counting the ones from visions and aborted timelines) and it seems as though the transformation is reversed when the nightmare state is dropped (excluding Nightmare Mirror, who wasn't on a physical plane of reality at the time anyway.) Princess Gaia's "good end" has been seen in AJ's dreams, as has Princess Bubbles - both of these appear to have become stable through some other means. This means has not yet been revealed.

The series as a meditation on philosophical and ethical principles
The POV series is extremely meditative on different ethical and moral principles, and touches on quite a few interesting topics.
 * Free Will
 * The series provides a potential defense of Free Will and Pain. In the fight against Nightmare Whisper, they tried to figure out if it was better to let one pony suffer everything so that all else would be happy. While the conflict ends with a hint of ambiguity, the game changer is that a world without suffering doesn't allow for ponies to grow into something better. Or to use an in-universe term, "Keeping butterflies as caterpillars."
 * Speaking of Butterflies arc: freedom of will is a dual power - from one side it can cause us to do horrible things but from another side, it's the same thing with help of which we do great things, it let us choose how to be and how world is going to be. Poor Pinkie, it was hard for her to accept it i think, what with the world of POV becoming divergent from the heart world.
 * Moral Ambiguity
 * The idea of moral complexity is very much used, particularly when it comes to reaching the 4th state of harmony. Applejack was probably the first of the mane cast to realize that on some levels, Discord was right in his accusations, and that there are ways in which their elements can be misused. This ranges from telling a truth with no potential benefit, laughing at someone rather than with someone, how we face a Sadistic Choice in every action we take, to that the magic of friendship can be lost if you don't maintain it since people do and will change. All these are acknowledged and used and even Celestia has admitted to making mistakes.
 * Forgiveness
 * The question of forgiveness is also constantly over the story, with the questions of fluttercruel, diamond tiara, silver spoon, and Trixie all begging the question: "Who deserves forgiveness, and how easily should they get it?"

Further Analysis of the Various Nightmares
NB: There is already some analysis of the Nightmares (Good stuff by the way. Very astute.), but this is what I found out. I will be adding to this as the series progresses.
 * Rainbow Dash's Nightmare (aka Nightmare Manacle): Nightmare Manacle is a very fitting name for RD's Nightmare persona. Loyalty is binding, connecting forever the people they apply to. When used correctly, loyalty is like flax, strong and flexible but able to be rotted away or broken if the loyalty means hurting others. It is not blind loyalty. Nightmare Manacle's loyalty is completely and totally binding. It does not allow for expansion if you want to be loyal to another person at the same time. Loyalty strengthens the people attached to it, but Nightmare Manacle's loyalty wears away at you like a heavy iron chain. It is a burden and not a privilege. Blind loyalty is worse than conscious betrayal.