Entulesse, Fosters in the Feywild
Most of the world's adult elves died in the wars following the Night of the Shattered Moon. The flower of an entire generation perished when the First Armada failed to invade the Shattered Moon. That failure led to the creation of a Coalition that retook the moon and fulfilled the mission of the First Armada.
Once the Far Realm was defeated the elven peoples faced slow extinction. There weren't enough elven babies being born to replace the ones who died in war and elven lands were ripe for invasion by their faster breeding neighbors.
A million of our sons and daughters died in the void, trapped and helpless. They never even saw the moon they were trying to save. Has the time of our people come to an end? Are we fated to vanish into memory?
The elven kingdoms jump started their populations by inviting half-elves and those with any elven blood to settle into the empty elven communities. They even extended invitations to any drow willing to make a life for themselves in the sunlight. But those efforts still weren't enough.
Toddlers & Time Warps
When the Orrery of Worlds began to stabilize the Kirinal Pit, the elves were the first to make bargains for the world of Erathia with extraplanar powers. They negotiated the Market Treaty with the Faerie Courts making Faerie the sixth day of the week in the new calendar.
The world's elves negotiated places for their children in quicktime areas of the Feywild. Elven infants born on Erathia could live out the hundred years of their childhood for a decade or even a few years. When they reached the age of majority at the physical age of 100 they come back to the world through the Market and begin their lives again in the mortal world.
A Childhood of Delight
The elves make sure that their children are born in the World, setting Erathia as their homeworld, ensuring that if the ever become lost in the dimensions that they will make their way to their proper home.
After their first birthday, they are taken to the Market on the day of Faerie and left with caretakers. They stay in the Manifest as it returns to Faerie and are taken to quicktime areas to enjoy carefree childhoods in well protected elven enclaves. They learn to sing and dance. They learn tales of their homeworld: the death of the goddess Thaya, the sacrifice of the First Armada, and the victory of the Second.
Preparation for War
When the children enter adolesence sometime in their physical 60's the youths are taken to camps where they learn the arts of war. They are taught to fight with sword, bow, and spell. They form close conections with their peers and they wonder about the parents they will meet again when they return to slow time and the mortal world.
Depending on which pocket of quicktime they were in, the infants return to the world as adult elves 5 to 10 years after they first entered the Market. Parents mourn the loss of their offspring's childhood, but they make the sacrifice proudly.
The elves have come back from near extinction fiercer and with a renewed lust for life.