|Legend of the Alicorn|
Vynil Planet (Parents: Silly Ray and Chess Arrow)
The Legend of the Alicorn is a very old legend: it says that two ponies with shapes in their eyes, a drop symbolizing water, a flower symbolizing earth and a cloud symbolizing air, would meet: the mare unicorn and the pegasus stallion would unite and create a fruit of foal(s), alicorns.
But not royal tall Alicorns with huge wings and long horns: just winged unicorns, horned pegasi, or even horned and winged earth ponies. It may seem happy... But the parents would have to die at midnight the day of their birth and the foals would die at the age of 20 if they don't un-curse themselves...
How get un-cursed
The kids have to do 3 things to get un-cursed:
The most basic thing, find a Cutie Mark. But there's no need of a Cutie Mark in every country. Just in Equestria! If the foals were born outside, they may not need to find one except to un-curse.
Find an Element of Harmony is maybe a little harder. The Elements of Harmony appeared one at a time: Loyalty, Laughter, then Kindness, Generosity, Honesty, Solidarity, and the new ones, GreenStylus gave Sympathy and Axe Day gave Tolerance.
And finally, get the universe in the eyes. Pinkie Pie thinks it means doing an action worth the sun and the moon. It's not easy to find out what it means, but they'll discover it sooner or later.
By un-cursing one fruit of foals, the Legend disappears for eternity.
Throughout the history
The Legend of the Alicorn, for short LotA, is more than million years old. At first they thought it was a happy accident. Some ponies examined the parents and found odd shapes in their eyes. But an old tyrant, Lord Crampmarch said there was no such thing and that they needed to be executed, burnt alive, like wizards.
The second family was a family too, since everypony forgot about the first family. But it was a mysterious pony who united them because he remembered. The kids, a colt and a filly were show-offs and pretended they were special. They both died at the age of 20, and that's how we discovered it.
Sunshine Stick, GreenStylus and Axe Day's mother, a great magician and scientist, found how to cure the disease and wrote everything down on a book. But nopony believed her and she lost a lot of money. But a Pegasus, Feather Dart who also had shapes in his eyes, believed her and wanted to give it a try. They dated, loved each other and had GreenStylus and Axe Day.
GreenStylus and Axe Day got un-cursed thanks to the Elements of Harmony, during their adventure http://mlp-gd.tumblr.com and the Legend was broken for ever.