For every pony, color is a prominent aspect of their character, both in their mane and their fur. It colonizes their cutie mark, regardless of when, where, and how the symbol is granted. They're divided into Pegasi, Earth Ponies, and Unicorns, all of these qualities defining exactly who they are, and what they will be.

Except for one pony.

Lumina, born without color or a cutie mark, doesn't even have as much as an association, being neither a pegasus, unicorn, or earth pony. She literally appears like a customizable avatar, without any defining feature -- not a single gene from a predecessor or a single spark of magic flooding her bloodstream. In simplicity, she's tangible, but nothing at the same time. However, when a traumatic event unfolds in Canterlot, her destiny will slowly unfold, showing that she is indeed something in this massive, unpredictable universe.

For 16 years now, ever since the cities of Equestria rebelled against Celestia, Canterlot has held the Hunger Games, where ponies between the ages of 6 and 17 are put into an arena to fight to the death. Every year, they pick a different city in Equestria to choose tributes from, and for the 17th annual Hunger Games, that city is Ponyville.
It doesn't matter if the Career Unicorns have a tactical advantage; every pony has to play the game, and here, you can't bend the rules like a board game...

One afternoon, when Twilight and Fluttershy are exploring antique stores, Fluttershy purchases a gem that claims to grant any wish she desires. Some may think she'd wish to have more animal friends, or to have better speaking skills. Instead, she wishes that she could fly like Rainbow Dash.
The next morning, Fluttershy wakes up. Except for one thing. She has no idea where she is, or why every pony expects her to go along with a lifestyle she never knew she had.
As a great unicorn once said, magic does what it likes. Sometimes, it changes all aspects of reality, and tweaks the future.

Did you ever wonder why Rainbow Dash had a rainbow mane and nobody else did?
Maybe it never crossed your mind that a rainbow is more than a superficial trait.
A little while after Rainbow fails her Wonderbolt audition, her friends begin to notice that her iconic rainbow mane and cyan coat are literally leaking color, leaving behind a shallow, lifeless shell of what Rainbow Dash used to be.
Without the old Rainbow Dash, everything seems to be thrown out of balance in Equestria, and the elements of harmony can't function. Together, they attempt to bring back color to the one they care for he most.
Through medical study and the magic of friendship, Equestria will finally understand Rainbow Pegasus ponies, and the existence of rainbows entirely.

Thirty moons of annoying bragging from Rarity.
Three years of jealousy and annoyance.
Sweetie Belle was fed up.

Ever since the historic battle of Twilight Sparkle and Sunset Shimmer 3 years before, Sweetie Belle had been curious beyond words. How could such powerful magic exist in the universe? How is there a world of equines?
"It's the magic of friendship darling," Rarity said countless times.
That answer never satisfied her.
One afternoon, Sweetie Belle discovered that the fabled magical portal had reopened for the first time in 3 years. She called her two friends, Scootaloo and Applebloom, and explained the news to them. They were unbelieving, but decided to travel with their best friend into the portal. When they got to the other side, they were indeed in Equestria, but it wasn't what they expected. It was a tragic world of disharmony.