Nyx's Family: Nyx and Spike travel to the Crystal Empire with Twilight Sparkle when she is called in to update the empire's library. Unfortunately, Shining Armor, whom she's staying with, has bitter feelings toward the filly formerly known as Nightmare Moon... and the Crystal Ponies, who were ruled by unicorn kings and queens and then enslaved by a unicorn tyrant, have bitter feelings towards anything with a horn...and this is before a gang of teenage dragons decides to raid the place in search of lost treasure. Complete.
Nightmare Night and Nyx: This is Nyx's first Nightmare Night, a holiday she has no knowledge of, especially the darker connections with her past. Complete.
Alicornundrum: After the events of Magical Mystery Cure, Twilight has become an Alicorn. However, not everyone's happy with the shift of power or how close Nyx is to the throne now, and both their lives are turned upside down by their new status as royalty. Incomplete.
Cheerilee's Class: This fic focuses on Willow Wisp, a thestral, moving to Ponyville and getting acquainted with the more eccentric members of his new class. Incomplete.
Bright Eyes, the friend Nyx makes through their shared love of Bilbo Burro (the Hobbit Expy), is this as well. They become fast friends after Nyx saves him from a Gang Of Bullies who were making fun of his Bilbo Burro plushie.
Alternate Universe: What with Nyx's presence, and everything. Oh, and apparently, Pinkie Pie was put in charge of reforming Discord, instead of Fluttershy.
Anachronic Order: The list above puts the stories in chronological order. In publication order, it's Nightmare Night and Nyx -> Nyx's Family -> Cherilee's Class -> Alicornundum.
Author Appeal: Immortality. Both the concept itself and the means to achieve it. Luna and Celestia are on a quest to bring immortality to the citizens of Equestria. The astute reader will pick up on several hints that this quest is eventually successful. For example, near the end of Nyx's Family, Rarity and Cadance get into a conversation over the peculiar beverage they are drinking. Rarity will eventually find herself thinking back on that talk more than a century later.
Author Filibuster: Considering who the author is, the truly interesting thing is how few of these there are. Reality Check clearly is more interested in telling stories here than expounding on his often controversial political views. Still, if you are looking for them, there's at least one example per fic, some much subtler than others.
Night Light: Don't mess with me, boy. I am one of Equestria's fierce beasts. I am the original steam powered animal; I have dual pistons and a built-in cowcatcher and I will roll over your tiny ego like a herd of pie-crazed buffalo. I have SEEN horseapples.
"I spent a portion of my daughter's cuteceneara day as a potted cactus. I nearly was father in law to a giant cock-a-roach. I have alicorns in my kitchen on a regular basis. My family pic-a-nics in Everfree Forest and likes it.
"The Elements of Harmony swap Hearth Warming gifts with us. The fruits of my loins are forces of nature, boy. My daughter juggles ursa minors for a pastime, makes Nightmare Moon sit in the corner when she's naughty, and turned a chaos god into a birdbath. She and her friends destroyed the Grand Galloping Gala and Princess Celestia applauded. My son slaps armies out of the sky by snogging his wife. My daughter in law sits on a THRONE and held the sky up for three days by sheer force of will.
Shining Armor chews out the parents and grandfather of an underachieving colt when they try to sign him up for the Royal Guard (Nyx's Family).
After putting six overgrown dragons in the hospital, Spike promises to do far worse to them if they ever threaten his friends again (Nyx's Family).
Twilight Velvet catches three nobles gossiping about her daughter's upcoming wedding and goes into full Mama Bear mode, verbally ripping them a new one (Alicornundrum).
Fed up with the petty scheming of the nobles bringing petitions before the throne, Twilight Sparkle unloads on them with such ferocity that two-thirds of them simply clear out on the spot (Alicornundrum).
So far, the only immediate family member who hasn't gone off on an epic tirade is Nyx. Word of God said that she would get hers in this verse's version of One Bad Apple.
Cerebus Syndrome: The stories never get too dark, but they do tend to get darker than they started out.
Continuity Snarl: It's small, and easy to ignore, but in Alicornundrum, Ink Spot claims to have been involved with Twilight by the time of the events of "Lesson Zero", which would place Nyx's Family and Nightmare Night and Nyx early on or before Season 2... except they clearly take place after "The Crystal Empire", putting them somewhere in Season 3.
However, this may mean that something caused it to happen later than in canon.
Department of Redundancy Department: One of the Royal Guards looking after Nyx is named Lightning Blitz, with Blitz being German for "Lightning". The author admits to the redundancy.
Glamour Failure: Special lanterns that act as a kind of Anti-Magic, dispelling Changeling disguises, are mentioned and show up multiple times throughout the series.
Hidden Depths: For Diamond Tiara of all ponies. Turns out one of the reasons she hates Nyx is she blames her for her father getting brainwashed in Past Sins and thinks she is a Karma Houdini who avoided punishment for it. She also helped Silver Spoon deal with a trauma-based fear, albeit in a meanie fashion.
Hollywood History: In-Universe, it turns out that the Hearth Warming's tale is this. For starter's, Chancellor Puddinghead was actually a brilliant scholar named Level Head ("Puddinghead" was a derogatory nickname by the unicorns and pegasi), and it was actually the Crystal Heart that scared off the Windigoes.
If You Ever Do Anything to Hurt Her...: Consistently subverted. When Twilight and Ink Spot start dating in Nightmare Night and Nyx, Shining Armor gives his "obligatory big brother greeting and death threat", but shrugs it off as a joke and says he likes the guy. And when the two become engaged in Alicornundrum, Twilight's father Night Light actually refuses to do this, stating that if he thought Ink Spot was the type of guy who might hurt Twilight, he wouldn't have let them date in the first place.
Modest Royalty: Celestia , Luna, Cadence, Shining, and Twilight are all, of course, this, since it is one of their defining character traits in the show itself. But it's really taken Up to Eleven with Nyx, who dislikes being reminded at all of the fact that she is royalty. Understandable, given how much she detested her tenure as Queen of Equestria and how her birthright to the title of Dark Queen of Equestria has been the source of every major trauma in her life, including kidnappings, multiple assassination attempts, and being feared and despised by many. Her royal status is essentially a trigger for her. The typical result when someone brings up the fact that she will inevitably be granted a royal title of some sort is as follows:
"But really, y'all," Applebloom said. "Nyx, Twilight Sparkle's a princess now. And that means sooner or later YOU'RE gonna be a princess too—"
Amplifier Artifact: Fire Opals make dragons grow larger, temporarily. In large doses, they can even grant extra heads.
Author Filibuster: Chapter 11, wherein Market Forces, an economist in the employ of the Royal Sisters, lectures the audience on the virtues of free market capitalism, and labels France's Ancien Regime as an example of the evil and oppresive nature of socialism, before we are treated to a flashback of Celestia and Luna using a magic mirror to consult HUMAN economists in order to create Equestria's economic system.(According to the author, because it was too much of a pain in the behind trying to "ponify" the names of various economists so as to be recognizable.) From that point on, no mention is made of the topics in that chapter. Word of God is these elements may reappear in future stories, however.
Brown Note: The MythBusters expys use a giant tuning fork against a dragon to try to invoke it: the tuning fork ends up breaking the fire opals he ate with… disastrous results. When asked if the myth was confirmed, Jamie wasn't sure.
Bullying a Dragon: Fluttershy tries the same method she used in "Dragonshy," which looks successful for a moment, but an angry maternal tone doesn't have the same effect on a dragon who disdains his mom.
Comic Book Adaptation: Fury of the Purple Dragon, on deviantART, focuses on Spike's transformation during the final battle. The author and the fans approve. Go to the Awesome page for a link.
Dangerously Genre Savvy: Sombra gets even more points with this here than just what he shares with his canon counterpart. Basically, the reason Twilight and Nyx (plus Spike and Peewee) go to the Empire is so Twilight could help reorganize the library system. They need to do this because Sombra had destroyed all their card catalogs, keeping anypony that wasn't him from finding anything so he wouldn't have to destroy information he might need later.
Genre Savvy: Nyx. Part of the reason she decides to give away most of the gifts she received after the attempted bombing (besides the fact that there wouldn't be any room in her room for her if she brought them all home and that it was fun to share) is that she's apparently read a story like that situation before:
Plus, she'd read enough books to know how this story went: the little filly gets all sorts of nice presents and then she turns into a horrible spoiled brat from getting so much stuff and has to have something terrible happen to her and learn an awful lesson at the end. Well no way was she going to fall into that trap! She'd already gone through turning into an evil Princess; flirting with one bad storybook plot in her lifetime was enough for her.
Glamour Failure: When Nyx is magically made to look like an ordinary filly, camera flashes briefly reveal her true appearance.
Power at a Price: The adolescent dragons learn the hard way why older dragons rarely gorge on Fire Opals.
Relationship Upgrade / Ship Tease: Rarity promises to give Spike a chance in a few years. Cadence assures her that it's not a false hope; they have ways of overcoming differences in species, size, shape, and eventually age.
Schizo Continuity: This fic conflicts with Pen Stroke's Winter Bells, in that both deal with Shining Armor getting over his fear of Nyx, but in different ways. What makes this significant is that part of another story in Pen Stroke's In The Family series is mentionednote Having Apple Bloom sit on an upturned basket with Nyx under it while Granny Smith calls the police, as described in Nightmare or Nyx. As such, Winter Bells is not canon to RealityCheck's Nyxverse.
Senseless Sacrifice: Spike attempts to persuade the attacking dragons to leave by offering himself up as requested. To no one else's surprise, it doesn't work.
Spit Take: Of the liquid-out-the-nose variety. Shining Armor does this multiple times in Chapter 4 with coffee, then orange juice, due to Nyx's actions and dialog.
Suicide Attack: Attempted by a lone terrorist. Fortunately, he didn't count on unicorns proficient in shield magic — and what he thought was the Equestrian equivalent of The Anarchist's Cookbook turned out to be a book of pranks.
Super Mode: This time, Spike's greed-induced growth spurt is this.
And not only because he's in control this time. He's much bigger and with Hulk-like muscles.
Nightmare Night & Nyx provides examples of the following:
Accusation Fic: The story briefly turns into one of these pretty much out of nowhere, when Bruce Mane reveals to Applejack that he knows about her being one of the Mare-do-Wells. Particularly jarring, since it has nothing to do with any of the surrounding story threads and relies a lot on non-canon events to make Applejack feel more guilty.
More appropriately, Celestia and others are made to feel guilty for perpetuating the old Nightmare Night traditions now that Nightmare Moon has become Nyx.
Adult Fear: Flitter goes off without her parents. They come looking for her in forbidden, decidedly dangerous territory.
Always Chaotic Evil: Subverted. Flitter and her parents reveal that the Changelings are not this trope. In fact, most of the species consider Chrysalis a "rabble-rouser" who almost destroyed their food source.
Anticlimax: A surprising number of chapters follow the biggest, most suspenseful event of the evening.
Author Filibuster: Bruce Mane lecturing Applejack on the Broken Aesop from "The Mysterious Mare-Do Well." Also Thunderlane urging Rainbow Dash to embrace her feminine side.
Disney Death: Nyx is seemingly killed by the conspirators, only for it to turn out she was just knocked out by her magic being drained. Of course, it is said in-story that a non-alicorn would indeed have been killed if they went through the process.
Discontinuity Nod: The Alphabet Conspirators' plan for Nyx, believing she's just a malignant blob of magic, is to dissipate her. This was originally what Celestia planned to do to Nyxnote if it turned out she was Nightmare Moon reborn in the original version of Past Sins.
In-Universe superhero BatStallion, a thestral, is one to Batman. Bruce Mane dresses as him for the ball. He is also the inspiration for BatStallion: He saved an aspiring artist from some thugs, and his transformation trinket accidentally got ripped off, revealing him to be a thestral. This inspired the artist to make a thestral superhero with a tragic backstory named BatStallion. Whether or not Bruce Mane is BatStallion isn't revealed.
Bruce Mane is dressed as BatStallion and turns out to be the In-Universe inspiration for the character.
Has Two Mommies: The realization that Nyx is technically related to Twilight leads to the realization that she may also be related to Luna by the same reasoning. After an epic Spit Take from Celestia (or was it Luna herself?) disguised as Nightmare Moon, she summarily discards the notion.
Hidden Depths: Pinkie Pie has an extensive education in psychology, which she explains is necessary to be the best party-planning pony possible.
I Can't Dance: Luna's as bad a dancer as Twilight. Then it turns out that was actually Celestia disguised as Luna.
Imagine Spot: When Twilight finds out about Celestia's hoof in her and Ink Spot getting together, she imagines her dancing on the ceiling above them holding marionette controllers.
Love at First Sight: Seems to be the case with Twilight and Ink Spot, though it's not until later that they admit their full feelings.
Mama Bear: Twilight towards Nyx, as per Past Sins canon. When she thinks the conspirators killed Nyx, she goes berserk and almost kills them. She's only stopped by Celestia showing that Nyx was still alive.
Fluttershy, also for Nyx, is no slouch herself.
Mind Screw: There's a lot of this In-Universe when it's revealed that Celestia and Luna have been impersonating each other off and on for most of the party.
Poor Pipsqueak suffers this when ponies try to explain the relationship between Nyx, Luna, and Nightmare Moon to him.
The Reveal: Played with. It was strongly implied that Ink Spot was an undercover Royal Guard... but it turns out he really is a book editor as he said, but one who's been hired to help the actual undercover guards keep their cover.
Shipper on Deck: Nyx and all of Twilight's friends are this for her and Ink Spot. And Celestia was pretty proactive about it too.
Ship Tease: Primarily Twilight/Ink Spot, but there's also Nyx/Rumble, Rainbow Dash/Thunderlane, Applejack/Bruce Mane, and Fluttershy/Caramel. (Pinkie Pie's time with Pokey Pierce gets little coverage; Rarity's time with Big Macintosh gets even less.)
Those Two Guys: Lightning Blitz and Sundiver, a pair of Royal Guards assigned to discretely watch over Nyx and Twilight.
Vegetarian Vampire: Apparently Twist's candy includes a secret ingredient produced by earth pony magic that is nutritionally equivalent to Changeling nectar (love bound to sugar water), solving Flitter's family's food supply problem. And before that they had been subsisting on the adoration of forest animals, plus it's implied that their original method of feeding on love from ponies wasn't harmful.
Writer on Board: Rainbow Dash feels uncomfortable slow-dancing and doing feminine things out in public, because she is afraid people will view her as weak and not awesome. This results in a scene where Dash realizes that her animosity to "frilly froufrou stuff" is leaving Scootaloo, who looks up to her as a role model, conflicted.
You Just Had to Say It: In Chapter 13, the other foals try to explain to Snails that there is no real Nightmare Moon, just Nyx. Snails points out that, if Nyx was grown of the scraps of Nightmare Moon, couldn't another piece have grown up and become another Nightmare Moon, too?
Scootaloo: Of all the times and places in the world, you had to pick THIS one to get smart...
Alicornundrum provides examples of the following:
Arranged Marriage: Lord Blueblood gets Night Light drunk in order to trick him into agreeing to setting up one of these between Twilight and Prince Blueblood. When Twilight finds out, she... forces him to sign an annulment. When he protests that he did so under duress, Celestia points out that she outlawed arranged marriages centuries ago (specifically that it constitutes rape, enslavement, and kidnapping, plus contractual fraud, blackmail, and treason in this specific case), so it'd be illegal anyway.
Technically, she didn't (probably couldn't) outlaw arranged marriages themselves. If all parties (bride and groom included) are in uncoerced agreement, then such a marriage arrangement is still legal. She got the other laws passed to kill the practice of trading heirs like possessions.
Big Bad: Lord Blueblood, who's willing to sink to any level to take advantage of Twilight's ascension to increase his family's own power.
Big Bad Wannabe: Ponies whom Duke Blueblood attempts to ruin tend to wind up better off through mysterious circumstances. Servants told they'd never work in Canterlot again win massive sweepstakes prizes, guards Reassigned to Antarctica get diverted to the verdant Crystal Empire... You'd think he would have realized he was outclassed by several orders of magnitude when that "uppity" cousin he married off to a brutish wife beater found herself a rich widow after a sudden crocodile attack.
Big Entrance: When Ink Spot hears about the above mentioned Arranged Marriage, he uses a network of unicorn teleportation to get to Canterlot, and bursts into the throne room wearing gryphon armor (loaned by a sympathetic gryphon), and challenges Prince Blueblood to a duel for Twilight's hoof in marriage. Even though the whole thing had been resolved already, it's still impressive.
Spike: (to Bright Eyes) That's how you make an entrance, dude.
Big Sister Instinct: Luna feels protective towards Nyx, and verbally rips Triton a new one when his poor word choice made her think she had accidentally killed thousand of sentient beings.
Big "YES!": Nyx's reaction to Twilight's ascension, and then to her and Ink Spot getting engaged.
Blackmail: After Twilight gets out of the Arranged Marriage, Lord Blueblood convinces his son to help him do this instead to gain control of her.
Continuity Nod: Twilight brings up how Celestia promised her that she and Nyx wouldn't be dragged into royal politics (at the end of Nightmare Night and Nyx) when protesting being made a princess.
Nyx talks Twilight into assigning Sundiver and Lightning Blitz to her security detail as a thanks to them for their heroics in Nightmare Night and Nyx.
Eureka Moment: Twilight ends up having one regarding how to fix the Celestial Council's problem, after a revisiting of Gossamer's Logic Bomb conversation.
Family Theme Naming: Killdeer, a young royal griffin Nyx meets at the summit, has a family tradition that gives the names of bird species to their griffin bodies and snake species names to their sentient snake tails, with Killdeer's snake tail being named Adder.
Genki Girl: Gossamer the Flutterpony, to the point that Nyx wonders if she and Pinkie are related.
Nyx: He may be all tough when he's running around with you, but he's all sweet and sensitive and vulnerable with me when we get his armor off. ...What? (Hoofmaids burst into laughter and Spike is facepalming) Whaaaat? What did I say?
Logic Bomb: Gossamer does this to the pony in charge of maintenance of Canterlot's central clock tower — the clock is how everypony in the city tells time, so how would they know how to reset it? Well, they'll just use the palace sundial. But what if Celestia sleeps late? Well, she'll have an alarm clock set, except how will they know how to set it if the clock tower isn't working? It's at this point that Nyx decides to lead the group away, while the poor pony is left facing an existential crisis.
Mama Bear: Celestia shows this side in spades when she tells off Lord Blueblood for trying to force Twilight to marry his son, going so far as to threaten him with the possibility of four death sentences if he doesn't drop the idea fast.
Celestia:DID YOU IMAGINE FOR A SECOND THAT I WOULD REFRAIN FROM BRINGING MY FULL POWER AND WRATH TO BEAR AGAINST ANYONE WHO TRIED SUCH A THING WITH MY MOST BELOVED STUDENT?
Twilight Velvet finally gets her Sparkle Clan brand moment of awesomeness in this manner, confronting three gossipy nobles.
Velvet: You won't have to worry about what Celestia will do to you because the last thing you will see in this world will be me taking a bite out of your still-beating hearts. Oh, and don't think I won't do it. My grandson is a dragon. I know how to get rid of the bodies.
Morton's Fork: The Celestial Council has made it's fair share of mistakes, causing numerous natural disasters, often because they don't plan ahead well. But without the Council, if the way things worked before it are any indication, things would be even worse than our world, with the forces being pretty much nonexistent instead of merely uncontrolled. Luckily, Twilight has a plan.
My God, What Have I Done?: An abstract example. Spike's intensive training, in which eggs represent ponies relative to his huge form, ends with only one egg unbroken. Rock Steady teaches him the hard lesson that enemies who don't care about your allies and bystanders may leave you little choice but to get reckless in the fight, possibly causing collateral damage yourself.
Twilight later discovers that the Celestial Council has a history of doing this themselves. Apparently, while many natural disasters are coincidental or designed to release pressure (like Pele causing small earthquakes to prevent large and destructive ones, etc.), a number of them are caused by the Council members screwing up at their duties guiding nature. For example, Pele messing up caused this universe's version of the Krakatoa eruption, or Jormungandr possibly causing the freeze from the Hearth's Warming tale, etc.
Noodle Incident: According to the footnotes, Ink Spot punched out a Diamond Dog in the badlands in the process of retrieving the diamond for Twilight's engagement ring; other than that, the only detail given is that it's a "long story".
Velvet apparently once fought off a manticore that threatened an infant Twilight.
Carp and dragons are apparently mortal enemies because of some sort of competition atop a waterfall in Neighpon.
Oh Crap: Blueblood had this when he learned Rarity is a Element of Harmony after the Gala.
Out-Gambitted: Duke Blueblood often attempts to ruin the lives of ponies he feels have slighted him in some way, yet fails to realize that Celestia is much better at manipulating things than he is, to the point that his "victims" are actually better off afterwards.
Painting the Frost on Windows: In addition to what the ponies do and Celestia and Luna's control of the sun and moon, the Celestial Council is pretty much responsible for making the world run smoothly.
Stop Worshipping Me: Celestia and Luna give this as the reason they crowned Twilight Sparkle almost immediately after she grew the wings — they themselves were worshipped zealously to the point that they literally had a castle built around them, so they know that Twilight would be worshipped whether she wanted it or not.
Also how Canterlot came to be — after Celestia banished Luna to the moon, she fled to the highest mountain peak she could find, only for the ponies to start building around her.
Take That: The whole Arranged Marriage with Blueblood thing is one aimed at a fic with a similar premise that the author hated (due to everyone from Celestia to Twilight carrying massive Idiot Balls throughout the entire story.)
Took a Level in Badass: In Nyx's Family, Rock Steady was brawny but not very educated or sure of himself; it took him two tries to pass an equivalency exam so he could join the Royal Guard. Shining Armor promoted him from Private to Lieutenant for his bravery in the battle against the dragons - leading three charges against them without losing a single soldier. As of Alicornundrum, he has been put in command of the "Heavy Platoon" and begun to display leadership and confidence.
Troll: Blueblood was being one when he was rude to Rarity during the Gala. He figured that she was a social climber (based off the fact that she was actually eager to be around him) and behaved like an absolute lout on purpose.
Wacky Marriage Proposal: More for the lead up than the proposal itself — When Ink Spot hears about the above Arranged Marriage attempt, he bursts onto the scene in gryphon armor and challenges Prince Blueblood to a duel for Twilight's hoof in marriage. Blueblood instantly forfeits, after which Twilight confirms that Ink Spot meant what he said; he responds by pulling out a horn ring he made on his way there.
Who Wants to Live Forever?: Nyx spends the first chapter angsting over the fact that she'll outlive everyone she loves and is thus overjoyed when Twilight becomes an alicorn.
Flitter's lunch consists entirely of candies made by Twist and infused with her equivalent of Changeling nectar (as explained in Nightmare Night and Nyx). The first time Willow sees Flitter, she's sucking on a candy cane during class.
Dark Is Not Evil: Willow is a thestral and thus looks like a walking Nightmare Night display, but he starts making friends once he realizes that most of his classmates are as off-center as he is.
Demoted to Extra: Willow is the viewpoint character for this story, and while Nyx does play a major role, she's not as prominent as in the other stories.
Dumbass Has a Point: When Cheerilee tells Snips and Snails that vamponies are an old mare's tale, Snails points out that everypony thought that about Nightmare Moon as well.
Ragtag Bunch of Misfits: The class counts. In addition to the ordinary students, there's an alicorn who was Nightmare Moon, a dragon who's now one of the two Champions of the Crystal Empire, a Crystal Pony who's the other Champion of the Crystal Empire, a Changeling, a zebra, a Sea Pony, a thestral, a half-pony half-Windigo... and the original Cutie Mark Crusaders.