(Note: MOD THREAD. Please do not post here.)
(Note: thread contains spoilers for existing Cadanceverse stories, as well as worldbuilding details)

Welcome to the Cadanceverse!

1000 years ago, Princesses Celestia and Luna of Equestria were corrupted by the mysterious force known only as Nemesis. Their golem construct, Cadance, took up the Elements of Harmony and banished them to the sun and moon respectively, then ruled the nation in their stead. For a millenia, she ruled it wisely and well, and the nation was prosperous and happy. She also taught some of Equestria's most talented musicians the secrets of their craft. Octavia Philharmonica, a very skilled musician who disdained the concept of friendships, was one such student.

At the end of a 1000 year period, the alicorns escaped from their prisons, but Octavia and five talented musicians from Ponyville took up the Elements and expelled Nemesis from the former princesses of Equestria, saving Ponyville, Equestria, and all the world. Now Octavia remains in Ponyville, learning about friendship and music from her newfound companions.

The further adventures of Octavia, Lyra Heartstrings, Medley, Bluenote, Fluttershy, Vinyl Scratch, Princess Cadance, and all the rest, are now open to the public! Let's all help Octavia and the others reach new heights by continuing their adventures.

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GENERAL GUIDELINES:

TONE:

Stories shouldn't be too much darker than M-verse. No gore, no extreme violence, etc. We can explore some more serious topics, but we should still endeavor to keep things true to the show's tone.

That said, there should be continuity and consequences. When characters take actions, those actions should reverberate beyond just the one episode, and if a character does something bad, they should be called on it and treated appropriately. But there should still be mercy, and forgiveness. It's My Little Pony, after all.

EQUESTRIA:

Equestria is a large nation on one of the continents that make up the Cadanceverse world. In size, I see it as comparable to maybe America, east of the Mississippi and north of the Mason-Dixon line. It holds about fifty million ponies.

The nation is governed as a constitutional monarchy. In terms of national power, The Throne (currently Princess Cadance and those she has devolved certain powers upon) has executive authority, and legislative power is vested in two bodies -- the House of Lords, made up of members of the nobility, and the House of Commons, made up of elected commoners. There is also a judiciary which is independent from the other branches. The Throne, House of Lords, and House of Commons all have roughly equal power, and it is partitioned such that no one branch can grow too powerful and destroy the others. (This does mean that Cadance can be thwarted if both the nobles and the common ponies disagree with something she wants; Cadance, seeing herself as accountable to the common pony and to her ministers, is fine with this. This rarely happens, though, since Cadance does govern justly).

On a more regional level, the nation is divided into many provinces. Some provinces are ruled by noble lords; the Philharmonicas, for example, run the duchy of Chenneigh, and the Lulamoons run the region around Neigh Orleans. Others are run democratically, with elected governors. On an even smaller level, towns are generally run democratically with elected mayors, though towns in provinces run by nobles do generally have to follow the rulings of that particular noble. Bad elected officials can be impeached and voted out; bad nobles can be brought to the attention of the Houses and the Throne, at which point they can be warned, punished, or even stripped of their titles in cases of extreme misconduct. This rarely happens, though.

The government as a whole is not corrupt or fundamentally flawed; while there may be individual bad elected mayors and representatives, and individual bad nobles, they are a small minority and can be defeated within the existing political structure. Most ponies are satisfied with their government.

Equestria is a prosperous nation with plentiful agricultural, high culture, and at the forefront of many technical advances. It maintains relatively friendly relationships with its pony neighbors, and even some non-pony nations in the area. In terms of military power, Equestria can probably defeat any other single nation around them, though it would be hard pressed if multiple nations teamed up. As such, Equestria relies on diplomacy to ensure this doesn't happen, and Cadance has thus far been quite successful at this.

In terms of social justice, Equestria is advanced beyond the real world. There is no sexual or gender discrimination, and same-sex relationships are seen in exactly the same light as opposite-sex ones. A few ponies might be tribalists (favoring one of the three tribes over another), but there is no widespread discrimination along those lines either.

PONYVILLE:

A small, rural town in the middle of the 'breadbasket' region of Equestria. It contains about 2000 ponies, ranging from babies and foals up to elders. The town is somewhat sleepy and removed from the bustle of Canterlot and the other big cities, but most of its residents are happy.

Ponyville is bordered by the Everfree Forest, a dangerous place full of monsters that love to gobble ponies up. As such, most local ponies know better than to go exploring within its depths.

The town has an equal mix of pegasi, earth ponies, and unicorns.

Ponyville, like most towns in Equestria, is run by a Council that is headed by a Mayor, in this case, Mayor Mare. Any pony can run for Council seats.

CHARACTERS:

RESIDENTS OF PONYVILLE

Element Bearers:

Octavia Philharmonica (Honesty). A cellist who used to study under Princess Cadance until she moved to Ponyville to study both music and friendship. Officially, she is working on a government project to chronicle the music of Ponyville and other towns in the region. She specializes in symphonic classical music.
Lyra Heartstrings (Kindness). A lyre player and busker. In love with Bonbon, but won't approach her until she's worked out exactly how to approach her. She specializes in bardsongs and ballads.
Medley (Loyalty). She builds instruments that play themselves, most recently having finished an aeolian harp. She runs a small music store and tries to pick up part-time hours on the weather team as well. She specializes in natural music.
Fluttershy (Generosity). She conducts her birds to play music. She serves as the town veterinarian, and she also advocates for a multitude of charitable causes. She specializes in ballroom and reception classical music.
Bluenote (Laughter). A tubist. She teaches foals music in and around the Ponyville area, and used to play in midlevel orchestras until she realizes she'd be happier elsewhere. She specializes in jazz.
Vinyl Scratch (Magic). She plays the drums and uses magical equipment to put on shows. She is a professional DJ. Her music specialty is wubstep.

Other residents of Ponyville:

Applejack: Apple farmer.
Big Macintosh: Apple farmer.
Apple Bloom: School foal.
Rainbow Dash: Weather captain.
Rarity: Fashion designers.
Pinkie Pie: Apprentice baker and party host.
Mayor Mare: Elected leader of the town.
Ditzy Doo: Mailmare.
Cheerilee: Teacher
Raindrops: Weather pony.
Cloud Kicker: Weather pony.
Blossomforth: Weather pony.
Bonbon: Confectioner.
Carrot Top: Carrot farmer and alchemist.

Tootsie Flute: School foal who specializes in the flute.
Beebop: School foal who loves loud music.
Silver Spoon: School foal who is interested in learning the piano so she can seem more refined.

RESIDENTS OF CANTERLOT:

Princess Cadance. Leader of Equestria.
Pageturner, personal assistant.

MEMBERS OF THE HOUSE OF LORDS

Octavia's mother, the Duchess of Chenneigh.
Trixie's mother, the Duchess of Neigh Orleans.

MEMBERS OF THE HOUSE OF COMMONS

Fluttershy's father, the Representative of the South Everfree Province.

RESIDENTS OF CHENNEIGH

Melody, Octavia's eldest sister.
Viola, Octavia's next eldest sister.

RESIDENTS OF THE EVERFREE

Zecora, protector of the animals.

OTHER

Nemesis, villainous entity.